ET DEBATE 1994 collected, edited and archived by Patrick Patriarca Included find all 4 sections of the External Tank debate which took place on the SPACE Conference on FIDONET in 1994. ALL posts have been included with the only "NET" symbols, headers, footers removed. The only other changes were spelling errors and naming of participants as PRO or CON. Patrick Patriarca - archivist The following series of posts are re-posts of a SPACE CONFERENCE debate/discussion/research which began when I asked about the possibility of using the shuttle External Tank as a space station. I was advised to contact Tom Abbott. The issue was the possibility of utilizing the Space Shuttle's External Tank (also referred to as the "ET" or "tank") as a space station and/or together with a space station. I endeavored to remain a neutral party in the debate as much as possible. As I do NOT believe in totally unbiased objectivity I will expose my "prejudices" from the outset. I was and remain quite intrigued by the possibility of utilizing the ET as a space station . Firstly it is HUGE and would give us A LOT of space in space :-). I also instinctively like the idea of using (recycling ?) as much of the shuttle materials as possible. I HATE throwing anything away ..ask my wife. Next, the IDEA of lofting the thing into orbit appeals to me. Imagine the sight! However ... ...do these reasons justify supporting the ET as a space station ... of course not. So therein was the rub and my need to scratch my researcher's itch. Thus I happened upon Tom Abbott, the then Chair of the National Space Society's External Tank Working Group. He agreed to take on all comers in a debate type format. I then became the default debate mediator (and I use mediator advisedly). Before getting onto the debate let me add that I am NOT totally sold on the idea nor am I against it ... I feel it has merit and is worthy of a solid investigation. Hugh Gregory has asked me to label the pro and con positions of the debate. Where possible I will do so. When I can't tell I have used "neutral" or a "?". Too those who participated in the debate ...forgive me if I put you on the wrong side of the debate (feel free to clarify) or forgot your name (some response names where only in abbreviated form). MY responses I will simply call "debate mediator", or PP unless my name is used. You will notice that some questions and responses are repeated. This is due to the nature of posting whereby people quote others and then those people quote themselves and the other person. I have tried to keep this to minimum but I decided to opt for clarity which means questions are often repeated. With that in mind ... on with the debate! (I originally queried Tom about the cost, necessary modifications to the ET, his credentials, sources of info. TOM ABBOTT (PRO): The cost to NASA to put an External Tank into orbit would be minimal. Of course, being NASA, it might run into a few million dollars for training of the astronauts to safe the ET. No major mechanical modifications would be needed just some procedural changes. The actual launch cost to orbit the ET would be zero since the Shuttle would be using fuel to orbit the ET, that is normally thrown away when the ET is discarded. I just got elected as Chair of the National Space Society's External Tank Working Group. That's why I went to the International Space Development Conference in Toronto. The Group was formed at the Conference. I get most of my information from reading a lot and from talking to the various experts I can find from time to time. A fully-loaded Shuttle might run the External Tank dry and require the OMS engines to give it the extra needed thrust to put the ET in orbit. The Shuttle has never carried its maximum weight. Shuttle flights of less than maximum payload could put their ET's in orbit using the fuel left in the External Tank. Thirty-six inch ports are standard docking ports. I don't know if they were made that way on purpose but they will sure work! The External Tank consists of three segments: the 92' long hydrogen tank; the intertank segment; and the 54' long oxygen tank. The three segments are bolted together and can be separated in orbit. The 28' diameter endcap can be unbolted from either end of the hydrogen tank or from one end of the oxygen tank giving you a 28' wide access to the tanks interior. How about an 8 meter telescope! DEBATE MEDIATOR In a separate private message I let Tom know that most people seem interested and hopeful about using the ET. I have said that a few are against of think it a foolish idea but that besides Tom no one (at this point) sighted (what seemed to me) credible sources for their (evidently) opinions. The following person's name I do not recall. (CON): Question #1: re: The problems include: the tanks are structurally flimsy when defueled" (PRO): How did you arrive at the conclusion that the External Tank is too flimsy to be converted into a space station. There are many dozens of studies of the ET space station conversion and none of them say the ET is too flimsy to use as a space station. The aluminum External Tank is stronger and its metal walls are thicker than America's one and only space station, Skylab. And Skylab performed very well. Skylab, BTW, was three times larger than the Russian's current space station, Mir, and the External Tank is three times larger than Skylab. (CON): Question #2: re: ...the newer tanks are brittle as well as flimsy, the construction material isn't intended to be exposed in space, and so on." (PRO): The new aluminum/lithium External Tank you're referring to hasn't even been built yet and it's not a sure thing that it will perform as desired even if it is built. Martin Marietta engineers aren't sure the aluminum/lithium will be strong enough to withstand a launch or whether it can contain the supercold hydrogen fuel. They also say the aluminum/lithium ET will only reduce the weight of the ET by 4,000 pounds instead of the needed 8,000 pounds. I would be interested in any studies you know of, which state that the External Tank (the all aluminum one) is unfit to convert into a space station. DEBATE MEDIATOR: I had asked earlier whether there were access port to the interior of the tank ... TOM ABBOTT (PRO): Thirty-six inch ports are standard docking ports. I don't know if they were made that way on purpose but they will sure work! Either Andy Reynolds or Darrell Holloway) (CON): The access holes may indeed be 36 inches in diameter, but they are basically manhole covers sealed using a naflex seal and dozens of bolts, nothing standard about that when you're talking about docking adapters. The US hasn't flown a "standard" docking adapter since Skylab. Just what he means by "standard" is anybody's guess. The access port on the ET isn't stressed in the local area for anything except ground use. Slapping a docking adapter onto it would only be the beginning of your troubles. DEBATE MEDIATOR (I also asked Tom about opening either end larger than the 1 meter docking ports ...) TOM ABBOTT (PRO): The External Tank consists of three segments: the 92' long hydrogen tank; the intertank segment; and the 54' long oxygen tank. The three segments are bolted together and can be separated in orbit. The 28' diameter endcap can be unbolted from either end of the hydrogen tank or from one end of the oxygen tank giving you a 28' wide access to the tanks interior. How about an 8 meter telescope! DARRELL HOLLOWAY (CON): While the LO2, intertank, and LH2 tanks are all interconnected by bolts, the aft closure domes of the two tanks are fusion welded to the cylindrical portions of the tanks. By the way, getting access to the bolts in the intertank is a B**** due to the curvature of the tank domes, getting to those hundreds of bolts on orbit, inside of the intertank (a cramped space even on the ground), in a EVA suit, borders on the insane. Thousands of hours were spent in designing Hubble so that the Astronauts could efficiently service it in orbit, and I've yet to hear of any interview with an astronaut involved who didn't credit their success to that design. The ET was not designed with any of this in mind, 36 inch access covers don't make up for that. No handholds, no tie downs, no reference markers, no access panels, nothing, this thing was never intended to be taken apart here on earth, let alone in orbit. The basic flaw with every argument I've ever heard regarding using ET's on orbit is that it is so easy to convert them to habitable workspace. Nothing is easy to do in an EVA suit, it is probably to most singularly expensive way to put a human's hands to work, EVER, considering the support costs required to get the astronauts up there and started working on the ET's. The cost of putting an equivalent amount of structural hardware in orbit pales in comparison with the amount of EVA work required to modify and outfit an ET in orbit. Build the station up from components put together on the ground, components built from the start to be processed that way. UNKNOWN POSTER (CON): What I was told is that a) the tanks would be structurally unsound if you start welding things to them, b) they are covered with (Or full of, I forget) a foam insulation which "Pop corns" in space. And c) the newest design for the tank uses a (Light weight) material which is extremely brittle, so they'd be structurally unsound _without_ welding things to them. (But I _still_ just like the sound of the idea.) TOM ABBOTT (PRO): The External Tank can be welded in some places and there are other areas which should not be welded. Since welding in space is potentially dangerous, most designs which outfit the External Tank in orbit rely on bolting components together rather than welding them. If the External Tank is outfitted on the ground before launch, as is proposed for NASA's Option C space station or the California ET space station, then welding is not a problem (as long as the thinner areas are avoided). The External Tank is covered with orange Spray-On Foam Insulation (SOFI) to insulate the ET, and the supercold fuel it contains, from outside temperatures. After the External Tank reaches orbit, it can be held in a 170 mile high orbit while the SOFI is scrapped off. One study predicts it would take less than a week to strip the SOFI, and the debris would deorbit in from hours to a couple of days, depending on the size of the piece. Another option is to leave the External Tank in a 160 mile high orbit for about a month and all the SOFI would oxidize off of it. If the External Tank were converted into a space station on the ground, the SOFI would not be applied in the first place. The lightweight material being referred to is a lithium/aluminum combination which would be a few tons lighter than the current all aluminum External Tank (if it's ever built). Lithium is a toxic metal which requires special handling. The Martin Marietta engineers working on building this type of tank are not sure it can be used to replace the all aluminum External Tank. There are questions as to whether lithium/aluminum can stand up to the launch stresses and questions about whether it can contain the hydrogen fuel. Tom Abbott NSS ET Working Group TOM ABBOTT (PRO): I would be interested in any studies you know of, which state that the External Tank (the all aluminum one) is unfit to convert into a space station. MIKE ZELESKI (CON): 1) Tell him to watch the vid on ET construction that runs periodically on Nasa select. TOM ABBOTT (PRO): Does someone in this video say the External Tank can't be converted into a space station? MIKE ZELESKI (CON): 2) Then he should get a design drawing of the Structure itself including the materials and tolerances involved with the assembly of the ET structure. TOM ABBOTT (PRO): I have design drawings of the External Tank. MIKE ZELESKI (CON): Then he should determine the needed design and material changes that must be made to the structure to simplify using it for something else. TOM ABBOTT (PRO): It's not necessary for me to do this. It's already been done. Dozens of External Tank conversion studies are available. MIKE ZELESKI (CON): I can name a few (problems) off of the top of my head... 1) Find a insulator that will not popcorn in a vacuume. It would have to be just as easy to use as the original spray on foam. TOM ABBOTT (PRO): Why use different insulation? The Spray on insulation currently used can be removed, and if an External Tank is converted into a space station on the ground, there is no need to add any Spray on insulation in the first place. MIKE ZELESKI (CON): 2) Replace the bolted on inspection covers with a simpler and easier method to enter the tanks. TOM ABBOTT (PRO): Not necessary. Convenient maybe, but not necessary.. MIKE ZELESKI (CON): 3) Provide internal hard points to attach things like machinery and storage bins to. TOM ABBOTT (PRO): Internal hardpoints are already provided. They're called "I-beams," and "ringframes." MIKE ZELESKI (CON): 4) Provide reinforced pre-punched places that will allow the mounting of external devices like a emergency radio, HVAC services, Air lock, Egress/access Tube, Electrical power, etc. TOM ABBOTT (PRO): The External Tank has built-in external hardpoints: at the places where the Space Shuttle and the two solid rocket boosters are mounted. A framework anchored on these hardpoints can support anything you want to mount on it. MIKE ZELESKI (CON): 5) Provide External fittings (Hard Points) that can used to attach the tank to another structure. TOM ABBOTT (PRO): The built-in ET hardpoints will serve this purpose. MIKE ZELESKI (CON): 6) Provide a way to vent any unburnt propellant overboard and then permanently close off the propellant lines to the shuttle on the tank side. TOM ABBOTT (PRO): Several methods have been proposed to accomplish this. MIKE ZELESKI (CON): 7) Provide a way to remove or disassemble the baffle structures inside the tank without damaging any vital structures. TOM ABBOTT (PRO): The baffle structures can be easily removed although it's not necessary to do even that. MIKE ZELESKI (CON): 8) Provide a easy way to disarm and remove the separation charges from the ET. TOM ABBOTT (PRO): This is a fairly simple operation. MIKE ZELESKI (CON): All of the above has to be done at a minimum of additional weight. That additional weight should not exceed more than 10% of present Shuttle Cargo capacity to prevent any loss of Shuttle functionality. (Less would be much better.) TOM ABBOTT (PRO): The External Tank requires very few modifications before launch, in order to be used in orbit, and most of these modifications add little or no weight to the External Tank. (DEBATE MEDIATOR) At this point in the debate I stressed to Tom (and those who challenge him) to post specific data and studies to bolster their position and NOT simply opinionate ... TOM ABBOTT (PRO): The baffle structures can be easily removed although it's not necessary to do even that. MIKE ZELESKI (CON): OK, maybe so again maybe not, but those additional sharp edges should be removed or padded to prevent injury. TOM ABBOTT (PRO): Wouldn't you agree that "padding or removing sharp edges" is within our current technical capabilities? MIKE ZELESKI (CON): Provide a easy way to disarm and remove the separation charges from the... TOM ABBOTT (PRO): This is a fairly simple operation. MIKE ZELESKI (CON): Bullhocky, your talking to a ExEOD expert, nothing dealing with explosives is easy or safe to do without many hours of practice... Especially since this requires a EVA just after the assent when the astronauts are still recovering from launch G's. TOM ABBOTT (PRO): From the Air Force Institute of Technology's "ASSET" External Tank study (1990): "The Space Shuttle External Tank contains range safety devices which would be detonated by ground controllers should flight problems arise. Once on orbit, this range safety system should be disarmed. Required modifications to the range safety system follow: 1. New wiring should be added in the range safety system (RSS) box enclosure. 2. Using existing cabling from the ET Orbiter I/F, the safing circuitry should be connected to the RSS box enclosure. Once the ET has been stabilized, the residual pyrotechnic charges in the LO2 [oxygen] and LH2 [hydrogen] tanks will be removed in a parallel operation." MIKE ZELESKI (CON): All of the above has to be done at a minimum of additional weight... That additional weight should not exceed more than 10% of present Shuttle Cargo capacity to prevent any loss of Shuttle functionality. (Less would be much better.) TOM ABBOTT (PRO): The External Tank requires very few modifications before launch, in order to be used in orbit, and most of these modifications add little or no weight to the External Tank. MIKE ZELESKI (CON): Beg to differ with you, it needs quite a few... TOM ABBOTT (PRO): The modifications mentioned above for safing the explosive devices on the External Tank plus tumble valve deactivation are the only modifications required before launch. All other modifications can be done in orbit. MIKE ZELESKI (CON): And almost all of them [ET modifications] will add weight/mass, while a few may actually remove a few ounces almost all will add something quite significant to it unless you are willing to bear the additional expense of sustaining a large enough Space construction crew to modify it. TOM ABBOTT (PRO): So you allow that modifications to the External Tank before launch would not be necessary if a large enough construction crew were available to modify the ET in orbit. MIKE ZELESKI (CON): At the cost of a 1/2 billion for each 10 mandays of labor towards converting a ET to a useful structure the expense of using a unmodified ET is simply too prohibitive to consider. TOM ABBOTT (PRO): I don't agree with your cost figure for labor. The Alpha Space station is projected to cost $1.3 billion per year to maintain four astronauts in orbit. Four astronauts could convert an ET into a space station in one year. It shouldn't cost any more to keep four astronauts aboard an External Tank than it would to keep them aboard the Alpha space station (and $1.3 billion per year is the highend cost, private enterprise should be able to do it a lot cheaper). Space Studies Institute estimates it would be possible to modify four External Tanks in orbit per year. Labor costs to modify an ET should be equal to or less than NASA's annual space station operating cost of $1.3 billion. Your estimate of $18 billion for a year's worth of labor in orbit is too high. Patrick's (DEBATE MEDIATOR'S) note to Tom: Tom- Why must the occupants of the shuttle do the work??? Why Can't whoever is doing the refurbishing stay there ... perhaps with a Soyuz TM as a return module??? My answer here depends on who does it, how and what you do ... costs are relative to the project ... do everything at once and costs differ from a pay as you go operation ... depending on just WHAT the ET is used for will determine what has to be done and how long to do it and how much. Again ... my thought would be to ASAP set up an environmental unit to allow "shirt sleeve" working environment ASAP and to do outside modifications on the ground ... (how am I doing???). TOM ABBOTT (PRO): Patrick, many studies of on orbit outfitting of External Tanks use a habitation module which is attached via an airlock to the ET. The construction crew lives in the module until modifications of the ET reach a stage where they can move into the ET as well (which should take place as soon as a breathable atmosphere is introduced into the ET) . The ET can be pressurized with a breathable atmosphere and the temperature will equalize soon after reaching orbit and all interior modifications could take place without being hampered by spacesuits, reducing the difficulty factor by orders of magnitude. When I talk about converting External Tanks in orbit that's the scenario I think of: a habitation module attached to the External Tank and a permanent crew that is not constrained by the Space Shuttle's schedule, modifying the interior of the ET in their shirtsleeves. MIKE ZELESKI (CON): Tell him to watch the vid on ET construction that runs periodically on Nasa select. TOM ABBOTT (PRO): Does someone in this video say the External Tank " can't" be converted into a space station? MIKE ZELESKI (CON): No, but it shows how it is built and it shows some basic flaws that would need to be overcome, before it could even be considered. TOM ABBOTT (PRO): What basic flaws are you referring to? MIKE ZELESKI (CON): I seriously doubt that he has the set (of plans for the ET) that has the failure to pass inspection for use tolerance limits that NASA uses. I could not get them, so how could he do so? Patrick's (DEBATE MEDIATOR'S) question to Tom: What are the "Failure to pass inspection for use tolerance limits", do you have those drawings or what drawings do you have. TOM ABBOTT (PRO): Patrick, I don't have them but the people I depend on for information do. MIKE ZELESKI (CON): Then he should determine the needed design and material changes that must be made to the structure to simplify using it for a space station. TOM ABBOTT (PRO): It's not necessary for me to do this. It's already been done. Dozens of External Tank conversion studies are available. MIKE ZELESKI (CON): Really? By who? Are they qualified to re-engineer a structure that designed to be as light as possible and is placed under very high stresses and is a fatal-failure structure. TOM ABBOTT (PRO): I would say they are definitely qualified to do that. (Sources will be forthcoming) DEBATE MEDIATOR'S NOTE: As soon as I ... Patrick.. receive more sources from Tom I will U/l them...note that Tom already sites one source and specific answers from ... the Air Force ASSET External Tank study of 1990 ... I suggest Tom's challengers find studies indicating the use of the External Tank is NOT possible or at least produce studies or data which disprove the ASSET (and other) studies. DEBATE MEDIATOR P.S.: ... 9/5/95 (within a day or so) marks SIX straight years that the MIR space station has been manned continuously ... something to think about people... MIKE ZELESKI (CON): ie I know that there are places in the ET structure that will not tolerate a predrilled mounting hole without doubling, collar welding, or some other type of reinforcement to preserve it's design strength. TOM ABBOTT (PRO): Well then, it would be a good idea not to drill holes in those particular places unless modified. DEBATE MEDIATOR (Patrick) asked: Of the ET conversion studies, who did them and what are their qualifications?? What about the "places in the ET structure" that will not tolerate changes ... do the designs or your plans, Tom, take these areas into account??? TOM ABBOTT (PRO): Patrick, I would say that the structure of the ET is the FIRST thing taken into account in these studies. I'll provide you with a separate source list shortly. MIKE ZELESKI (CON): I can name a few (problems) [with converting ETs] off of the top of my head... Find an insulator that will not popcorn in a vacume. It needs to be just as easy to use as the original spray on foam. TOM ABBOTT PRO: Why use different insulation? The Spray on insulation currently used can be removed, and if an External Tank is converted into a space station on the ground, there is no need to add any Spray on insulation in the first place. MIKE ZELESKI (CON): If it [SOFI] can be removed then in what? A big plastic bag? I can imagine it now... Oh how crude... Come-on this is a very critical problem, this popcorned foam is the Space equivalent of Hazardous waste on Earth. Can he say Micro-Metorite? Scatter enough debris like this in LEO and even the Shuttle will need its tiles replaced every time it is launched. TOM ABBOTT PRO: Removing the SOFI at a 170 mile high orbit will allow the pieces and particles of insulation to deorbit within a matter of a few days. Can you say shortlived micrometeorite? MIKE ZELESKI (CON): Replace the bolted on inspection covers with a simpler and easier method to enter the tanks. TOM ABBOTT (PRO): Not necessary. Convenient maybe, but not necessary. MIKE ZELESKI(CON): Very necessary, EVA time in space is expensive, on the order of thousands of $ per min, TOM ABBOTT (PRO): EVA is much less expensive if the crew lives at the External Tank where they can modify it at their leisure instead of being constrained by the amount of time the Space Shuttle can stay in orbit (28 days). MIKE ZELESKI (CON): and those bolts [on the External Tank hatch cover] are big compared to anything they have done in Space so far. TOM ABBOTT (PRO): You're not saying it's impossible to unbolt the hatch cover in orbit are you? MIKE ZELESKI (CON): Did you watch the Hubble Repair, they had to use power screwdrivers on ordinary #6 screws and such. A fast acting design is much less expensive to build on Earth than trying to unbolt a lot of bolts during EVA. So the bolt number must be dropped quite a bit. TOM ABBOTT (PRO): Any cost savings realized by modifying the ET on the ground would be offset by recertification costs. I did watch the Hubble repair, it was fascinating. And I think if I had a #6 screw to remove here at the house I would use a power screwdriver myself. Anyway, it's kinda hard turning a hand screwdriver in a spacesuit. While we're on the subject of the Hubble repair: no operation associated with converting an External Tank into a space station in orbit is as difficult as some of the tasks the astronauts performed in repairing Hubble. If anything proves humans can work in space the Hubble repair does. MIKE ZELESKI (CON): Provide internal hard points to attach things like machinery and equipment TOM ABBOTT (PRO): Internal hardpoints are already provided. They're called "I-beams," and ringframes." MIKE ZELESKI (CON): Device specific mounts must be provided for anything that creates any vibration. TOM ABBOTT (PRO): What would prevent us from doing this in orbit?. MIKE ZELESKI (CON): Drilling holes in any of the Tank structures in Space will also contaminate the Tank with sharp little bits of metal. Imagine what they can do...This is better done on Earth when it is being made when gravity can help you to collect those fragments, and just becomes a part of all of the junk that collects inside the Tank while it is being made. TOM ABBOTT (PRO): Not necessary. Any metal particles can be controlled using enclosures and vacuum cleaners. Besides, the ringframes have lots of holes already in them, just waiting for someone to put a bolt in. But I agree the more modifications done before launch the better; but only up to a point. Modifying the ET before launch is certainly much easier than in orbit but these modifications can also take place after the ET is in orbit, it's just harder and takes longer than doing them on the ground. The problem with modifying the ET on the ground is you reach a point, depending on the number of changes made, where it will have to be completely recertified. It will take longer to retest and recertify the ET after major modifications than it would take to outfit a plain vanilla ET in orbit even taking into account the increased difficulty of doing the conversion in orbit. I'm all for prelaunch modifications that don't require recertification of the External Tank. DEBATE MEDIATOR- Tom ...my understanding there is that anything floating ends up by the air vents (circulation) why not collect the debris there??? TOM ABBOTT (PRO): Patrick, everything floating loose in a space station eventually ends up at the air vent (if it doesn't get into something else first!). You would want to remove any metal particles from the ET's interior before installing delicate equipment which could be contaminated by them. MIKE ZELESKI (CON): Provide re-enforced pre-punched places that will allow the mounting of external devices like a emergency radio, HVAC services,Air lock, Egress/access Tube, Electrical power, etc. TOM ABBOTT (PRO): The External Tank has built-in external hardpoints: at the places where the Space Shuttle and the two solid rocket boosters are mounted. A framework anchored on these hardpoints can support anything you want to mount on it. MIKE ZELESKI (CON): 3 out of 6 directions is not good enough in Space where you can build (and sometimes have to.) in any direction. Also it is difficult enough in Space to unscrew a pipe plug and screw antenna-camera_lens-ect. through it, try suiting up, evacuating the Tank and cutting a hole instead. Again you have to do EVA time to do something that should be simple to do if the structure properly designed in the first place, Look at SpaceLab and all of the protrusions that it had through it's pressurized shell. Your suggesting that all those protrusions should be cut through the ETskin after it is up in Space. DEBATE MEDIATOR Patrick asked: Don't quite follow Mike here Tom do you??? Perhaps you WANT to build in 6 directions but what is the problem with 3?? Why does he refer to cutting a hole in the ET??? I don't recall you suggesting that. TOM ABBOTT (PRO): The outside hardpoints are sufficient for mounting whatever is required. And no Patrick, I didn't suggest cutting holes in the External Tank (that lets all the air out). DEBATE MEDIATOR: Here is Part III of Tom Abbott's responses to questions and challenges regarding the Useable External Tank . Most of these questions and challenges are from Darrell Holloway who works (worked??) on the Space Shuttle at KSC: TOM ABBOTT (PRO): The cost to NASA to put an External Tank into orbit would be minimal. DARRELL HOLLOWAY (CON): This much is true *IF* you only wish to orbit an empty tank with no provisions for later use as proposed TOM ABBOTT (PRO): No major mechanical modifications would be needed just some procedural changes. The actual launch cost to orbit the ET would be zero since the Shuttle would be using fuel to orbit the ET, that is normally thrown away when the ET is discarded. DARRELL HOLLOWAY (CON): Also true, but with the same proviso as mentioned above. If you intend on doing anything with the tank the story changes TOM ABBOTT (PRO): I don't quite follow you here, Darrell. How does the story change? DEBATE MEDIATOR Tom Abbott to Patrick: I just got elected as Chair of the National Space Society's External Tank Working Group. I get most of my information from reading a lot and from talking to the various experts I can find from time to time. DARRELL HOLLOWAY to the DEBATE MEDIATOR Patrick (CON): No offense Patrick, but I don't see that Tom here has any better credentials than most of us in this discussion, we all have an interest, all have access to the technical information, and all have access to those more closely associated, and in my case I have some direct knowledge.< TOM ABBOTT PRO: I think it depends more on how the technical information is interpreted. My credentials aren't the issue. It's the credentials of the people I'm quoting that count. DARRELL HOLLOWAY to the DEBATE MEDIATOR (Patrick) (CON): So why should Tom's credentials be given any more weight than anyone elses? TOM ABBOTT (PRO): If I'm offbase I imagine it will become apparent fairly quickly. DARRELL HOLLOWAY (CON): Being elected Chair of a group designed to head up a cheer-leading squad for the ET based Space Station doesn't carry much weight. It's just a title give by a popular vote. TOM ABBOTT (PRO): Maybe not with you, but my little 10 year old nephew thinks it's a big deal! Please don't bust his bubble. DEBATE MEDIATOR'S NOTE: At this point your Default DEBATE MEDIATOR wishes to note I "religiously" include ALL challenges and questions to Tom's position (note the length of these posts)... I have no set position and Tom's responses DO NOT carry more weight ... he has a position and others are welcome to challenge it. He DOES include references to studies supporting his position. If that gives him more weight ...so be it. His references to studies are NOT Gospel ... but they are studies with data. I suggest countering with opposing studies or hard data. Witness that I have included EVERYONE'S post ... Tom HAS begun siting specific studies from seemingly reputable sources ... I STRONGLY suggest those who differ either site sources that deny these studies validity and/or studies and/or data to prove the findings incorrect ... However, this has not YET been done ... as always ... " Data will out ..." TOM ABBOTT (PRO): Thirty-six inch ports are standard docking ports. I don't know if they were made that way on purpose but they will sure work. DARRELL HOLLOWAY (CON): There is no such thing as a "standard docking port", the docking adapter used on Apollo/LEM/Skylab was different than that used on Apollo/Soyuz and different from that about to be used on the Shuttle/MIR missions If size is the only thing he is concerned with then his interests are entirely off the mark. The size of the portal that the docking adapter will mate to is the least of the worries, adapting up or down is easy, attaching the adapter to the ET port will be the issue. The ET access port on the bottom of the LH2 tank is basically designed like a large blind flange, bolted on with dozens of very large nuts/bolts and was never intended to be opened and resealed using the same seal, certainly never designed with an eye towards ease of access and manipulation by an astronaut in an EVA suit. TOM ABBOTT (PRO): But none of those reasons will prevent using the hydrogen tank's access hatch. The access hatch would not be used to try and reseal the hydrogen tank, an airlock would be used for that purpose. DARRELL HOLLOWAY(CON): And the area around the port was never designed, from a stress and fatigue point of view, to accommodate a docking adapter and the accompanying loads which it would impart to the ET during use. TOM ABBOTT (PRO): Trusses can be installed that will carry all the loads on the airlocks. The intertank region of the External Tank is the strongest part of the structure and an airlock located there can certainly handle any kind of docking stresses it would encounter. An intertank airlock added before launch would be extremely convenient. It could connect to both the hydrogen and oxygen tanks and to the outside as well. DEBATE MEDIATOR to audience: Tom SEEMS to answer the challenge re: the Intertank/airlock location after Darrell's next statement: DARRELL HOLLOWAY (CON): To my knowledge, and I looked it up, the three sections are bolted to each other, the tank hemispherical end-caps are fusion welded to the rest of the tank, no bolts there at all. Even so, the hundreds of bolts used to join the sections together would be a nightmare to access in space. They are located in the intertank where the hemispherical end-caps of the LO2/LH2 tanks meet the sidewall of the intertank itself, a very narrow, very hard to reach location, even on the ground by a worker in a shirt sleeve TOM ABBOTT (PRO): From the "ASSET" study: "The intertank is the structural connection between the LO2 and LH2 tanks. It is a skin/stringer/frame structure of cylindrical shape with external stringers and internal frames. The intertank's primary functions are to receive and distribute all thrust loads from the SRBs and transfer loads between the propellant tanks. Weighing roughly 12,200 lbs, the only non aluminum components of the intertank are steel fasteners and SRB fitting socket inserts. Additionally, the intertank serves as a compartment for housing instrumentation and range safety components. Access into the intertank compartment can be gained through a nonstructural 52 inches high by 46 inches wide access door (the opening measures 48 inches high by 42.7 inches wide). Prior to launch, the intertank compartment can be outfitted with operational hardware so that requirements for cargo space in the Orbiter payload bay can be minimized. The intertank will serve as the strongback for the ASSET facility. Solar arrays and orbital maintenance hardware will be attached to the intertank, taking advantage of its structural rigidity. Connectors for the three power distribution systems will be installed in the forward dome of the LH2 tank. Installation will be accomplished from within the intertank. The astronauts will then ingress the LH2 tank via the aft manhole opening." Tom continues: Looks like THEY don't think there will be any problem getting into the intertank. In fact, the intertank is large enough to fit a 4 foot wide by 8 foot long airlock into it. The airlock could connect to both the hydrogen and the oxygen tanks and to the outside as well. This would give astronauts three separate places to take shelter in case of problems in one of the other areas. DARRELL HOLLOWAY (CON): [the ET will] have to be re-engineered to provide for a non-propulsive method of venting off the residual cryogenics onboard. I have seen still photos taken on a mission in the not too distant past where the 2 inch gaseous hydrogen disconnect valve on the ET failed to close properly (spring loaded to the closed position once the tank separates from the Orbiter) and the venting GH2/LH2 produced an coupled pitch/roll motion. Not a motion you'd like to see your future space station module get cozy with before you have a chance to attach stabilizing avionics and attitude control devices. Also, the ET tumble valve would of course have to be disabled prior to flight. TOM ABBOTT (PRO): The Shuttle would remain attached to the ET until the fuel was vented, to keep it under control. DEBATE MEDIATOR: Tom seems to have again used the ASSET study re: the Intertank question ... while not the "Bible" on ET Useage it IS a study ... again are there any recognized studies that deny the ASSET findings or are more valid?? DARRELL HOLLOWAY(CON): The foam insulation used on the ET serves to protect the ET and it's contents from the aerodynamic heating of ascent but in some areas it also protects the ET from the hot recirculation zone at the base of the LH2 tank where SRB/SSME exhaust gasses are a threat. Of course on the ground the insulation revents excessive propellant boil-off and also ice formation on the tank skin. This foam in space however, as others have mentioned, is a real threat to spacecraft in the local space environment and will require special attention. Tom's answer was so simplistic as to be naive... "taking it off". Of course it would have to be taken off, but I have yet to see a realistic approach as to exactly how this would be accomplished by astronauts in EVA suits with limited EVA time to play with. The tank is HUGE, the foam is thick and in many places the exterior of the tank is ribbed/slotted so that no amount of simple mechanical stripping of the foam will get to it all. I have yet to see any detailed answer to this issue, all seem very simplistic and only half baked. TOM ABBOTT (PRO): From the Air Force Institute's "ASSET" ET study: "One way Spray-on insulation (SOFI) can be removed without adversely impacting the EVA budget is to use an automated SOFI removal system. Using the same rail truss that the electron beam cutter rode to cut the LO2 (oxygen) barrel, another electron beam device could move over the surface of the ogive sections, spraying a defocused electron beam. This defocused beam would remove the SOFI in 22 hours. This operation would produce a great deal of very fine SOFI debris. Estimates show, however, that this debris would deorbit on average in half a day." DARRELL HOLLOWAY (CON): In one reply Tom promotes taking the ET into a low orbit where the foam could be removed or allowed to erode away, then move it to it's final orbit. Move it with what, good intentions? The ET doesn't have it's own propulsion system and once separated from the Orbiter it's separated for good, so how do you get it into the higher orbit? A simple problem, but it requires a not so simple solution. TOM ABBOTT (PRO): I guess I shouldn't have assumed that you would assume that a propulsion module had already been attached to the ET before any of these movements took place. I'll try to be more specific. In all on-orbit External Tank space station conversion proposals, a propulsion system is installed just as soon as is practical and the External Tank remains attached to the Space Shuttle until this is accomplished. Positive control of the ET at all times is the only acceptable way to operate. DEBATE MEDIATOR Tom ... a thought hear from me (Patrick).. WHY must the insulation on the ET be taken off... if flaking is a problem ... why not wrap the ET in a micometeor cover (sort of a sock... or LARGE "condom") contain the insulation ... less work (especially if lofted separate OR as part of the shuttle launch) and if entire ET is covered contain insulation and use it as insulation to maintain temp of ET??? Just some thoughts TOM ABBOTT (PRO): Patrick, a meteor bumper like you describe is incorporated into many ET designs and would solve the insulation problem if the entire ET was covered. DARRELL HOLLOWAY (CON): All of Tom's solutions are simple by default, and usually unworkable in that form without much further study and modifications of hardware. TOM ABBOTT (PRO): Sometimes the simplest solutions are the best solutions. DARRELL HOLLOWAY (CON): and... If the NSS is really serious about using ET's as space station components then I suggest that they get their handsdirty, dig into the nuts and bolts of the ET design and stop using NASA's press releases (written on an 8th grade level) as their source of info. They should use their heads as though it were them about to have to spend hours and days and weeks in an EVA suit doing all of this work, and stop just passing off issues as "easily solved" without taking the time to REALLY see just what is required. .... TOM ABBOTT (PRO): I couldn't agree more. DARRELL HOLLOWAY (CON): There are many more vital issues, most addressed by Andy or Mike, that I won't go into. Bottom line for me (don't you just love hearing that term used and abused over and over again?) is that while the use of the ET at first glance seems attractive, it simply does not stand up to good hard engineering review. TOM ABBOTT (PRO): I have seen no engineering review that would rule out using the External Tank in orbit. I would be interested in any you know of. DARRELL HOLLOWAY (CON): I too have seen some of the studies you mention, but I have yet to see an in-depth review by Martin- Marietta (the tank designer) with positive support for this application. TOM ABBOTT (PRO): Try the study by Robert L. Price, Senior Structures Engineer, NASA Space Systems, Martin Marietta Astronautics, Denver. DARRELL HOLLOWAY(CON): and...I think Andy, Mike and myself have established our credentials, how about Tom giving us some real nut and bolt answers for once, not just more generalities and over-simplifications. TOM ABBOTT (PRO): Well, I'll do my best. DEBATE MEDIATOR: And now a few words from your Default Self-proclaimed Great Useable External Tank Debate DEBATE MEDIATOR .... As I said originally I have no set position on whether the ET is Useable as a Space Station ... I AM fascinated by the idea ... Tom has been (correctly) challenged with insightful and excellent questions. The best have challenged his ideas as him using NASA'S "eighth grade" press releases for sources ... Tom has responded with two data sources ... the Air Force ASSET study and Martin Marietta's study by Robert Price, Senior Structures Engineer ... again while not GOSPEL and the last word on this debate they ARE *seemingly* bonifide studies. If they are not does anyone have a study challenging these two studies OR better sources?? In research studies with data are at least a beginning to finding a goal or answer. The External Tank issue evidently dates to the mid-1980's. PRO studies have been done as evidenced by Tom Abbott's sources. If the External Tank idea is so flawed I would think there would be ONE study showing where there are problems. The gauntlet has been thrown down challenging Tom's sources... he seems to be responding with interesting sources ... any challenges to their validity??? Inquiring minds want to know (g) .... DEBATE MEDIATOR: NO sooner did I post the above 'DEBATE MEDIATOR" message then Tom Abbott sent me a list of references... TOM ABBOTT (PRO): Patrick, I see you got the messages. Good. Here are a few references pertaining to using External Tanks in orbit. There are many more. References pertaining to reusing Space Shuttle External Tanks: *Brin, D., "The Future of the External Tank: The Key to Space?"L-5 News, Feb. 1983. *First Steps to Lunar Manufacturing: Results of the 1988 Space Studies Institute Lunar Systems Workshop, Space Studies Institute, P.O. Box 82, Princeton, New Jersey 08542. *Haislip, J.N., Raynes, W.C., Van Matre, D.L., Linscott, R.E., Skinner, M.A., "An Aluminum Salvage Station For The External Tank (ASSET)" Department of the Air Force, Air University, Air Force Institute of Technology, Wright Patterson Air Force Base, Ohio, Dec. 1990. *Robert L. Price, Senior Structures Engineer, NASA Space Systems, Martin Marietta Astronautics, Denver, Colorado, "Preflight Modifications and OnOrbit Assembly Configurations to Enhance Obital Utilization of Space Shuttle External Tanks." *Chern, Terry S., "Utilization of Space Shuttle External Tank Materials by Melting and Powder Metallurgy," Acta Astronautica, 12:693-698, September 1985. *Gimarc, J. Alex, "Report on Space Shuttle External Tank Applications", Princeton, NJ, Space Studies Institute, December 1985. *Martin Marietta Corp., Michoud Division, "Space Shuttle External Tank System Definition Handbook. New Orleans, LA: Martin Marietta Manned Space Systems. *Martin Marietta Denver Aerospace, Michoud Division, "STS [External Tank] Propellant Scavenging System Study. Final Report NAS8-35614. 1985. *Martin Marietta Manned Space Systems, "External Tank Gamma Ray Imaging Telescope Study. Final Report NAS8-36394.1987. *Martin Marietta Manned Space Systems, "External Tank Gamma Ray Imaging Telescope (ET GRIT), Neutral Buoyancy Simulation Test. Test Report NAS8-36394. 1988. *Martin Marietta Manned Space Systems, "Preliminary Data for Onorbit Utilization of the External Tank. Prelimary Data. New Orleans, LA: NASA George C. Marshall Space Flight Center, 1988. *Martin Marietta Manned Space Systems. "External Tank Gamma Ray Imaging Telescope Study, Phase 4. Final Report NAS8-36394. Huntsville, AL: NASA Marshall Space Flight Center, 1990. *Stone, William C. and Christoph Wiutzgall, "Evaluation of Aerodynamic Drag and Torque for External Tanks in low Earth orbit." In Proceedings of the National Institute of Standards and Technology, pages 37-46, 1988. *Pagano, A.R. and Enright, E.M., Martin Marietta Space Systems, "Ground Integrated ET-Derived [External Tank] Space Platforms for Onorbit Applications," Proceeding of the Eleventh Space Studies Institute/Princeton/American Institute of Aeronautics and Astronautics Conference: Space Manufacturing 9, The High Frontier: Accession, Development and Utilization, Princeton, NJ, May 12-15, 1993. *C.B. King, A.J. Butterfield, and W.D. Hypes, The Bionetics Corp., Hampton, VA; J.E. Nealy, Spacecraft Analysis Branch, Langley Research Center, NASA, Hampton, VA; L.C. Simonsen, Planning Research Corp., Hampton, VA, "A Concept for Using the External Tank From a National Space Transportation System (NSTS) for a Lunar Habitat," Proceedings of the Ninth Princeton/AIAA/SSI Conference: Space Manufacturing 7: Space Resources to Improve Life on Earth," Princeton, NJ, May 10-13, 1989. PART 2 - THE GREAT EXTERNAL TANK as SPACE STATION DEBATE DEBATE MEDIATOR: At this point the debate seemed bogged down. I then read over the voluminous posts and attempted to refocus the debate by playing a bit of devil's advocate and seeking answers to what I perceived to be problematic aspects of the External Tank/ Space Station idea. DEBATE MEDIATOR: The question again, as I try to bring focus to this discussion, is specifically what the ET is to be used for. Which will determine difficulty and the need for changes. It seems the question is just how much we want or need something the ET's size. I think there is no question we do. The bottom line is cost and the ability to do the work in space.< TOM ABBOTT: PRO: Patrick, the External Tank should be used as the basic building block of our space program. According to the experts, the cost is billions cheaper. And as far as our ability to work in space goes: if we can assemble the Alpha spacestation in orbit then we can assemble an External Tank spacestation in orbit. ET critics usually fail to mention just how much on-orbit assembly the Alpha spacestation is going to require. The External Tank modifications will take more on-orbit time but the ET would still be finished (2001) before Alpha (2003, maybe!), even if we waited until next year to start. The cost of on-orbit outfitting of an External Tank ranges from $100 million for a man-tended facility to from $300 million to $4 billion (depending on who you ask) for a full-fledged External Tank spacestation. A $26 billion+ savings over the Alpha spacestation. NASA's $13 Option C External Tank spacestation design (which is put together on the ground instead of being assembled in orbit) is $17 billion cheaper than the $30 Option A (Alpha) spacestation (which is assembled in orbit). So the External Tank Spacestation is faster, cheaper, better and bigger than the Alpha spacestation, whether the ET is assembled on the ground or in orbit. That ought to be reason enough to use the External Tank! Isn't that Daniel Goldin's slogan: faster, better, cheaper? DEBATE MEDIATOR: The following post was between Bryan Beatty and Patrick Patriarca (DEBATE MEDIATOR) ... Tom Abbott responded ... BRYAN BEATTY ( Quoting Bryan Beatty to Patrick Patriarca ) The Saturn V is far and away the biggest rocket which the US has ever built, and (I think) the third-largest in the world. (I believe the Russian Proton and Energiya have bigger payloads.) It was designed for the very impressive mission which you describe: send a very big payload all the way to the moon. DEBATE MEDIATOR: Small .. correction to an otherwise good post ... the Proton lofts 40-45,000 lbs to LEO ... payloads such as the MIR and its modules. Saturn V, Energia and the Shuttle system (after all the STS DOES loft 200,000 lbs each trip) are all about the same ...a revived SATURN V would likely be the largest as the F-5 engines have been uprated. BYRAN: Okay... I suppose i goofed with regards to the Proton. Surely the shuttle doesn't belong in that list, though-- I was talking about *payload* to orbit. Perhaps the shuttle puts 200,000 pounds up each time, but I wasn't counting the Orbiter... isn't its payload now only 30 tons or so? TOM ABBOTT: PRO: Bryan, that depends on what you consider payload. I personally would consider the Space Shuttle's External Tank as cargo which adds another 30 tons to the 30 tons carried in the Shuttle's cargo bay. That also cuts the Shuttle's cost per pound to orbit in half. The Space Shuttle launch system can put about 140+ tons into low-Earth orbit: Space Shuttle=75 tons; empty External Tank=30 tons; cargo=30 tons; residual fuel in External Tank=5 to 20 tons. Replacing the Space Shuttle with a cylindrical cargo carrier and three attached Space Shuttle Main Engines would give us a vehicle capable of putting approximately as much cargo in orbit as the Russian heavy-lift launch vehicle, Energia: about 90 to 100 tons. The Saturn V is (was) the most powerful launch vehicle in the world having the capability of putting up to 130 tons in orbit. Question from Patrick Patriarca to Tom Abbott concerning External Tank spacestations: DEBATE MEDIATOR: The question again, as I try to bring focus to this discussion, is specifically what the ET is to be used for. Which will determine difficulty and the need for changes. It seems the question is just how much we want or need something the ET's size. I think there is no question we do. The bottom line is cost and the ability to do the work in space. Tom responded: PRO: Patrick, the External Tank should be used as the basic building block of our space program. According to the experts, the cost is billions cheaper. And as far as our ability to work in space goes: if we can assemble the Alpha spacestation in orbit then we can assemble an External Tank spacestation in orbit. DEBATE MEDIATOR: But surely the amount of work to be done on the ET model would be MUCH more than launching modules of the Alpha station ...even if the Alpha station requires some amount of assembly. TOM (PRO): ET critics usually fail to mention just how much on-orbit assembly the Alpha spacestation is going to require. The External Tank modifications will take more on-orbit time but the ET would still be finished (2001) before Alpha (2003, maybe!), even if we waited until next year to start. The cost of on-orbit outfitting of an External Tank ranges from $100 million for a man-tended facility to from $300 million to $4 billion (depending on who you ask) for a full-fledged External Tank spacestation. A $26 billion+ savings over the Alpha spacestation. DEBATE MEDIATOR: I wonder how the ET could cost so much less and do the same things the Alpha/International station could do. Figuring that the outside shell of Alpha or the ET is not the costly part but the internal modules how does the cost of the modules (with all their electronic gear) go down. I would presume the same module would go in each since we are talking about the ET doing the same things the Alpha could do? How does the cost of the module go down? Besides, the modules for the ET would have to be lofted either by expendable rocket OR (God forbid) the Shuttle. In either case your cost immediately rises. Since we are assuming the ET and Alpha would perform the same tasks, and therefore need virtually the same modules how could the cost be less as both would cost the same to loft the modules ... TOM ABBOTT: PRO: NASA's $13 Option C External Tank spacestation design (which is put together on the ground instead of being assembled in orbit) is $17 billion cheaper than the $30 Option A (Alpha) spacestation (which is assembled in orbit). DEBATE MEDIATOR: The Shuttle C (which I assume you are referring to as it is the only way to loft an ET already assembled) is not possible in the near future. It would require retooling, test flights, all the research prior to launch. No way it would be done within 10 years. No way. TOM ABBOTT: PRO: So the External Tank Spacestation is faster, cheaper, better and bigger than the Alpha spacestation, whether the ET is assembled on the ground or in orbit. That ought to be reason enough to use the External Tank! DEBATE MEDIATOR: Given the amount of basic research work needed on the Shuttle C option I doubt the cost would be much cheaper ... the Shuttle C would be virtually another HLV which would require extensive research $$$ which simply are not available ... much of that is likely to go into SSTO vehicles (if we are lucky. I see no way that $$$ will be available for a Shuttle C system. Would that we already had it ...but we don't and won't. TOM ABBOTT: PRO: Isn't that Daniel Goldin's slogan: faster, better, cheaper? DEBATE MEDIATOR: Yes it is. And I share it. However I am sure his Prime Directive is to do what is safe and doable. He may be wrong but my impression is that NASA doesn't now feel it has the ability to construct, virtually from scratch a space station using the ET. I mean one launched on a typical STS flight and needing near total construction in space. I imagine NASA's view is that is is one thing to do work on the HUBBLE for a few hours on a craft that was built for that purpose. And costing (relatively) little compared to constructing an entire space station. We are talking nearly totally new ground here. Constructing, from scratch, a space station, as opposed to putting together modules. While I certainly share your desire to see a station the size and capability of the ET the REAL POLITIK of the situation tells me that it will not happen before Alpha cum International Space station (which is the way we will go...international cooperation with Russia, Europe, Japan et al) . My REAL POLITIK sensor tells me that AFTER the International station is built and we prove we can construct such a complex THEN the ET option will become viable ... I know it sounds backwards and perhaps it is. I'm not saying it's right but rather that it is REAL POLITIK reality. Not the way I would want it to be. Just the way it is. IF the ET option is so cheap and doable I recommend private funding. Certainly 3-4 billion $$$ is doable from the private sector. I would use the ET as a business, to salvage and repair satellites (GEOS-6 comes to mind ...it's only problem is being out of fuel) and expended boosters ( there are a large number of Centaur boosters up there in LEO). With an OTV (Orbital Transfer Vehicle) such as a larger robotic Progress tug or a larger DC-X type vehicle with 4 Centaur engines we could be in business. Given the cost of lofting and each of these satellites (50-200 million apiece??) cost should be recouped and profits seen relatively soon. I still share your enthusiasm for the ET station. I think it will/can happen. It seems to make technical sense. Given greater confidence in building structures from scratch. But not before the Alpha/International station. If it is to come it will come after the Alpha. I hope I am wrong. I think I am not. TOM ABBOTT: PRO: Patrick, the External Tank should be used as the basic building block of our space program. According to the experts, the cost is billions cheaper. And as far as our ability to work in space goes: if we can assemble the Alpha spacestation in orbit then we can assemble an External Tank spacestation in orbit. DEBATE MEDIATOR: But surely the amount of work to be done on the ET model would be MUCH more than launching modules of the Alpha station ...even if the Alpha station requires some amount of assembly. TOM ABBOTT: PRO: Hi, Patrick, glad to hear from you. The Alpha spacestation requires a lot of on-orbit assembly: about 350 hours. Outfitting an External Tank in orbit would take more total time than Alpha, since you're starting from scratch, but Extravehicular Activity (EVA) time for the ET conversion wouldn't be any more than that required for Alpha. Interior modifications to the External Tank can be made without the necessity of wearing spacesuits because the interior can be pressurized with a breathable atmosphere after the airlock is attached. Working in shirtsleeves instead of spacesuits greatly simplifies and speeds the modifications. DEBATE MEDIATOR: I wonder how the ET could cost so much less and do the same things the Alpha/International station could do. TOM ABBOTT: PRO: Patrick, NASA is not the final word on what something should cost. Just because they can't build a spacestation for less than $40 billion doesn't mean it HAS to cost that much. Explain to me why an "underfunded" NASA would choose to build a $30 billion spacestation if they have the option of building a $13 billion spacestation. NASA management has its own way of looking at things. (BTW, when I say "NASA" I mean the people at NASA and in the administration who have the power to make changes. NASA employees have nothing but my respect. I know what it's like to work with Federal bureaucrats and try to change things, all it takes is one blockhead in a position of power to stop innovation. So NASA employees, don't take my remarks personally, they're meant for your bosses.) DEBATE MEDIATOR: Figuring that the outside shell of Alpha or the ET is not the costly part but the internal modules how does the cost of the modules (with all their electronic gear) go down. I would presume the same module would go in each since we are talking about the ET doing the same things the Alpha could do? How does the cost of the module go down? TOM ABBOTT: Patrick, one ET is equal to 10 Alpha modules. One of the big differences in cost is the number of launches required to put all the equipment in orbit. The $30 billion Alpha spacestation will require about 32 launches. NASA's $13 billion Option C spacestation would require one launch. Space Studies Institute estimated it would require 2 Shuttle launches and one Titan IV launch (or equivalents) to put the equipment in orbit to outfit one External Tank and turn it into a spacestation. DEBATE MEDIATOR: The Shuttle C (which I assume you are referring to as it is the only way to loft an ET already assembled) is not possible in the near future. It would require retooling, test flights, all the research prior to launch. No way it would be done within 10 years. No way. Given the amount of basic research work needed on the Shuttle C option I doubt the cost would be much cheaper ... the Shuttle C would be virtually another HLV which would require extensive research $$$ which simply are not available ... much of that is likely to go into SSTO vehicles (if we are lucky. I TOM ABBOTT: PRO: Patrick, the Option C study predicted it could produce a heavy-lift vehicle by 1999. It wouldn't require retooling, all the equipment required for External Tank modifications are already on hand at Martin Marietta. Conversion of the External Tank into a heavy-lift vehicle is one of the most studied designs in the history of our space program; studies such as the Shuttle C you mention, and Shuttle Z, and Option C, and National Launch System, etc. This modification can be done with very little pain and little risk, since it's a cargo vehicle and no people will be riding it. DEBATE MEDIATOR: I see no way that $$$ will be available for a Shuttle C system. Would that we already had it ...but we don't and won't. TOM ABBOTT: PRO: Patrick, one way would be to axe the Alpha spacestation and replace it with the Option C spacestation. That's saves $17 billion immediately. That ought to be enough to build several SSTOs! The Air Force is estimating a cost of $29 billion to build a new heavy-lift vehicle. If we implement NASA's Option C proposal which includes a heavy-lift vehicle in its $13 billion cost, we can save the Air Force and ourselves another $29 billion. I vote we apply this money to a Moonbase! Isn't that Daniel Goldin's slogan: faster, better, cheaper? DEBATE MEDIATOR: Yes it is. And I share it. However I am sure his Prime Directive is to do what is safe and doable. He may be wrong but my impression is that NASA doesn't now feel it has the ability to construct, virtually from scratch a space station using the ET. TOM ABBOTT: PRO: Well then, let's contract with Space Studies Institute (a non-profit organization) to build an External Tank spacestation for them and us. They claim they can build one for about $2 billion, assembled in orbit. The $2 billion is adjusted for inflation and the increase in Shuttle launch costs: from $120 million per launch in 1988, when their ET study was done, to approx. $500 million (can you believe that!!!) per launch today. DEBATE MEDIATOR: I imagine NASA's view is that is one thing to do work on the HUBBLE for a few hours on a craft that was built for that purpose. And costing (relatively) little compared to constructing an entire space station. We are talking nearly totally new ground here. Constructing, from scratch, a space station, as opposed to putting together modules. TOM ABBOTT: PRO: Patrick, it's not totally new ground, remember, we'll be working from a habitation module. If we can assemble the Alpha spacestation in orbit, we can also assemble the External Tank spacestation in orbit. DEBATE MEDIATOR While I certainly share your desire to see a station the size and capability of the ET the REAL POLITIK of the situation tells me that it will not happen before Alpha cum International Space station (which is the way we will go...international cooperation with Russia, Europe, ·_ TOM ABBOTT: PRO: Patrick, REAL POLITIK depends on the political wind, which changes all the time. DEBATE MEDIATOR'S NOTE: Charles Radley SEEMED to challenge Tom Abbott so I risk placing him in the CON category ..apologies if I am incorrect ... TOM ABBOTT: PRO: TA> Patrick, one ET is equal to 10 Alpha modules. CHARLES RADLEY:(CON): Only in volume. ET is an empty shell. TOM (PRO): Charles, that's what I meant. CHARLES:(CON): The Alpha modules contains: life support, power, propulsion, communication, temperature control, computers, science experiments, etc... These systems weigh several times more than the aluminum pressure shell.. TOM (PRO): Charles, the weight of these systems does have to be added into the equation and was taken into account in figuring launch requirements. One of the big differences in cost is the number of launches required to put all the equipment in orbit. The $30 billion Alpha spacestation will require about 32 launches. NASA's $13 billion Option C spacestation would require one launch. Space Studies Institute estimated it would require 2 Shuttle launches and one Titan IV launch (or equivalents) to put the equipment in orbit to outfit one External Tank and turn it into a spacestation. CHARLES(CON): This is a pig in a poke. What will be carried on the Titan-IV and single shuttle launch ? TOM (PRO): Charles, life support, power, propulsion, communications, temperature control and computers will be carried on these launches. CHARLES:(CON): In reality to get a useful space station, several Shuttle launches are n needed for each ET launched. The empty ET shell has to be filled with many tons of equipment. TOM (PRO): Charles, isn't "several shuttle launches (2) or equivalents" what I said previously? CHARLES(CON): Plus everybody forgets the weight of all the food, oxygen and water needed to feed and house the construction crew for the several months it would take to assemble everything into the ET. TOM (PRO): Charles, food, oxygen and water will be required on ANY spacestation we build, ET or otherwise, so I don't include that cost when comparing the Alpha spacestation to an External Tank spacestation since it's the same for both. CHARLES:(CON): No useful science can be done during that period. TOM (PRO): Charles, if we implemented Option C now it would still be completed before the Alpha spacestation, so useful science could begin earlier with Option C than with Option A. CHARLES(CON): This work is also dangerous with high risk of accident, congress does not like accidents. TOM:(PRO):Charles, the ET outfitting work isn't anymore dangerous than assembling the Alpha spacestation in orbit. TOM (PRO): heavy-lift vehicle. If we implement NASA's Option C proposal which includes a heavy-lift vehicle in its $13 billion cost, we can save the CHARLES:(CON): How does this compare to $ 150 Million to launch it on Energia ? TOM (PRO): Charles, a Shuttle-Derived Heavy Lift Vehicle may be comparable to Energia in cost. The cost figures I've been given on the Ground-Integrated Option C spacestation proposal were: $5 billion to construct the spacestation; $3 billion to develop the heavy-lift part of Option C; and the other $5 billion was for operating costs. I don't know what the launch cost for the Shuttle-Derived Heavy Lift Vehicle would be. It may be comparable to Energia's $150 million cost. Then again, if it costs us $300 million to launch a Titan IV maybe we won't be able to get the SDLV launch costs down to quite that level. Of course, when Russia gets its currency straightened out the cost of Energia may rise dramatically. And besides, I like the idea of having an American heavy-lift vehicle. I feel less dependent that way. The Department of Defense and NASA are talking about spending up to $29 billion to develop a heavy-lift vehicle. If they would implement Option C they could save this money for use elsewhere (Moonbase!). TOM (PRO): Well then, let's contract with Space Studies Institute (a non-profit organization) to build an External Tank spacestation for them and us. They claim they can build one for about $2 billion, assembled in orbit. CHARLES(CON): Hey, I think I can build one for $ 1.5 billion. Please mail your check to the address in my sig, and I will start work right away.... TOM (PRO): Charles, sounds like you don't know Space Studies Institute very well if you compare them to just anyone walking down the street with a screwball idea. Fact is, Space Studies Institute includes some of the heaviest hitters in the space community. CHARLES(CON): Seriously though, the SSI has never flown anything. It is easy to make such claims....much harder to fulfil them.... TOM (PRO): Charles, sounds like you're describing NASA, they haven't flown any spacestations either. Skylab doesn't count; that was Wernher von Braun's baby, back when NASA knew where it was going and why. And speaking of Skylab, America's one and only spacestation, it was fully assembled on the ground before launch and was launched into orbit using one launch just like NASA's $13 billion Option C spacestation. NASA is currently cutting space science projects and satellites to the bone; is cutting back employees; and isn't even sure they will be able to fund the Alpha spacestation. In light of this, can you explain to me why NASA would choose a spacestation design that costs $30 billion (Option A/Alpha) when they have the option of choosing a $13 billion (Option C) design? To add insult to injury, Option C would be finished sooner and would be larger than Option A (Alpha) and Option C would develop a heavy-lift vehicle; Option A doesn't. The Alpha decision certainly wasn't based on the technical merits. And BTW, the recent Clementine mission to the Moon was dedicated to Space Studies Institute's founder, Gerard K. O'Neill. CHARLES RADLEY to TOM ABBOTT(CON): Hey, I think I can build one for $ 1.5 billion. Please mail your check to the address in my sig, and I will start work right away.... Seriously though, the SSI has never flown anything. It is easy to much such claims....much harder to fulfill them.... DARRELL HOLLOWAY(CON): Bravo. It's also much like someone trying to tell you how easy it is to build a ship model in a bottle, when in fact they've never built any ship models at all, let alone one inside a bottle. Every issue you point out to the ET Space Station crowd is met with the same type of response: no problem we'll just ___________. (you fill in the blank). Their fixes are not addressed any more realistically than their concepts. For example, how does one keep ET's from tumbling out of control and also get them from the low earth orbit where the insulation will be scrubbed away, to the higher orbit of the station? Ans.: No problem, a propulsion and control module will be attached before the shuttle ever disconnects. Hmmm, what propulsion and control module? When will it be designed? When will it be built? When will it be tested? What fuels will it use? Will it go up with each shuttle taking an ET up for the station? (wait a minute that would eat into the shuttle's payload, and they promised that taking an ET into orbit would be free). How will it attach to the ET? What do you do with it once the ET is in the correct orbit? Will it require an EVA to connect it or will it be done remotely? Do they think hardware like this gets left by the Tooth Fairy? Sometimes that's what they sound like. No problem's solution is complex, no problem's solution takes time, money, or manpower, you simply do it. Astronauts in EVA suits apparently will be Godlike in ability to handle anything, any eventuality, any unforeseen problem that normally happens in a construction environment on the ground where engineers can be called in for hands on evaluation if needed and the design or tool altered to correct the issue. Their answers are too simplistic, too nearsighted, too optimistic. Weren't they paying attention when the Hubble repair mission flew? Didn't they understand the ten's of thousands of hours of simulation time required by the EVA crews, the millions spent in designing hardware which could be installed successfully, with no help from the ground, in zero-G. Apparently not, they plan to stuff the innards of an entire Space Station Alpha into the thin skinned shell of an ET through a small airlock whose physical dimensions will constrain the size of each component and make integration much more involved. No problem. Darrell Holloway TOM ABBOTT (PRO): Darrell, to turn your statement around: it's also like someone trying to tell you how hard it is to build a ship in a bottle, when in fact they've never built any ship models at all, let alone one inside a bottle. And the ET is a mighty big bottle. DARRELL:(CON): Every issue you point out to the ET Space Station crowd is met with the same type of response: no problem we'll just ___________. (you fill in the blank). Their fixes are not addressed any more realistically than their concepts. TOM ABBOTT (PRO): Darrell, that's a matter of opinion, of course. The only issues I see raised by the "anti-ET Space Station crowd" (which amounts to three or four people as far as I can tell) are amorphous things like: "it too hard; it's not realistic; it's too simplistic; you don't understand how hard it is; etc. These are all opinions. If we judge by opinions I think I can produce many more opinions on my side of the argument than you can for your side. DARRELL(CON): Hmmm, what propulsion and control module? When will it be designed? When will it be built? When will it be tested? What fuels will it use? TOM (PRO): Darrell, what propulsion and control module will the Alpha spacestation use? Who will design and build it. When will it be tested? You are saying the Alpha spacestation, which requires a propulsion module, is viable, but an ET spacestation that requires a propulsion module, isn't viable. What's the difference? DARRELL(CON): Will it [propulsion module] go up with each shuttle taking an ET up for the station? (wait a minute that would eat into the shuttle's payload, and they promised that taking an ET into orbit would be free). TOM (PRO): Darrell, taking an ET into orbit would be free. And for the present discussion, I'm talking about outfitting one ET in orbit. One ET will require one propulsion module, which will remain attached to it. It could be a Russian FGB propulsion/power module or a customized unit. A propulsion module is required by an ET spacestation but it's also required by any other spacestation in orbit including Alpha. A requirement for a propulsion module is no argument against using External Tanks. DARRELL(CON): Do they think hardware like this gets left by the Tooth Fairy? Darrell, I guess you think the "ET spacestation crowd" is rather silly. One of those "ET spacestation" people is the former general manager of NASA's Freedom spacestation program. He's now senior vice president of External Tanks Corp., a company that has a contract with NASA for five External Tanks delivered to orbit. I think he probably has a good idea of what a spacestation requires and whether it's feasible to convert an ET into a spacestation and what it costs. He's actually worked on these problems in the real world. Shouldn't his opinion carry a lot of weight? DARRELL(CON): Sometimes that's what they sound like. No problem's solution is complex, no problem's solution takes time, money, or manpower, you simply do it. TOM (PRO): Darrell, no one said working in orbit or building a spacestation is simple; but it's not impossible either. What's ironic is that NASA astronauts have no trouble completing their tasks in space; while NASA apparently finds it impossible to complete its spacestation tasks on the ground. DARRELL(CON): Astronauts in EVA suits apparently will be Godlike in ability to handle anything, any eventuality, any unforeseen problem that normally happens in a construction environment on the ground where engineers can be called in for hands on evaluation if needed and the design or tool altered to correct the issue. TOM PRO: Darrell, the astronauts I'm familiar with don't seem to think they'll have any trouble working in space. One of them said, "just tie my feet down and I can do anything in space that I can do on the ground." Shouldn't their opinions carry quite a bit of weight? DARRELL(CON): Weren't they paying attention when the Hubble repair mission flew? Didn't they understand the ten's of thousands of hours of simulation time required by the EVA crews, the millions spent in designing hardware which could be installed successfully, with no help from the ground, in zero-G. TOM PRO: Darrell, the Hubble repair was a one-shot-only deal with no second chances available. And NASA's neck was on the block. Outfitting an ET would not be constrained by the Space Shuttle's limited orbital staying power as was the case with Hubble, since the astronauts would remain in orbit and operate from a self-contained habitation module. The astronauts can outfit the ET slowly and safely. DARRELL(CON): No problem. TOM PRO: Darrell, less of a problem than Alpha, and cheaper and faster, too. TOM ABBOTT PRO: To: ALL From: TOM ABBOTT Public Date: 11/15/94 at 22:02 Re: California External Tank NASA report OKs California External Tank spacestation proposal. At the request of California's Governor Pete Wilson, Senator Dianne Feinstein,and other California Space Program enthusiasts, NASA evaluated the technical feasibility of converting Space Shuttle External Tanks (ET) into spacestations. The External Tank is the large orange fuel tank the Space Shuttle is attached to at the time of launch. The ET carries all the hydrogen and oxygen fuel for the Space Shuttle's three main engines. By the time the Space Shuttle is almost in orbit the ET is nearly empty and is traveling at a speed of about 16,000 mph. If the Space Shuttle crew were so inclined, they could take the ET right on into orbit with them. Presently, the ET is jettisoned back into the Earth's atmosphere where it burns up. California's Spacestation Project aims to take an empty ET and convert it into a spacestation on the ground so that it is fully assembled and ready to be occupied right after it is launched, in the same manner as was done with America's previous spacestation, Skylab (1973). The reason they propose to use an ET rather than a customized tank is that the tooling is already available to modify the ETs, which makes it much faster and cheaper to convert an ET than to design and build a custom tank from scratch. They estimate it would take about two years and cost about $4 billion to convert an ET into a first-class spacestation. $300 million would buy you a barebones ET spacestation. Mark Holderman, former head of NASA's Option C spacestation proposal --a design similar to the California ET spacestation--is the principal designer of the California ET spacestation . Gene Meyers is the California Spacestation Project's driving force and a longtime advocate of using External Tanks. The California Spacestation Project proposes to launch the ET spacestation into orbit by taking three Space Shuttle main engines and attaching them to the bottom of the ET spacestation and then bolting the ET spacestation onto the side of a fuel-carrying external tank and attached solid rocket boosters. The ET spacestation would replace the Space Shuttle in this configuration but would not carry crew or passengers, and would launch itself into orbit. Future plans call for taking the empty fuel-carrying External Tanks into orbit where they can be converted into spacestations for sale to interested parties, instead of allowing them to fall back into the atmosphere and go to waste. California ET spacestations would be launched from California's Vandenburg Space Shuttle launch facility into 400-mile-high polar orbits, where they would complement NASA's spacestation which will travel in a more equatorial orbit; each orbit having its own unique advantages. The California Spacestation Project would be funded by Federal and State tax credits which requires no Federal or State money up front but rather guarantees the return on private investors' money. NASA was asked to evaluate the External Tank spacestation proposal, as a first and important step in the realization of California's goal of turning polar low-Earth orbit into their next business district, which they predict will generate hundreds of thousands of new jobs for job-starved California. NASA's report to California is that there are no technical obstacles to the conversion of External Tanks into spacestations or the launching of them into orbit. This (and the Republican election landslide) should clear the way for legislation to be reintroduced into Congress which would open up space to private enterprise to a much greater degree by giving them the ability to raise the funding required through tax incentives. Space paying its own way; much better than spending tax dollars! The next two years will be interesting. Many influential Republicans have been pushing for a long time to open up space to private enterprise and they may now be in a position to do it. California may be the first of many to benefit from these events. CHARLES RADLEY (CON): Plus everybody forgets the weight of all the food, oxygen and water needed to feed and house the construction crew for the several months it would take to assemble everything into the ET. TOM ABBOTT (PRO): Charles, food, oxygen and water will be required on ANY spacestation we build, ET or otherwise, so I don't include that cost when comparing CHARLES (CON): No, I am referring to the EXTRA food and water etc. required to house the construction crew. TOM (PRO): Charles, I'm not sure how many people you're including in the construction crew but I'm using a figure of four people. Figure about 5 tons of supplies per month. One Russian Proton at $60 million per launch could supply the ET spacestation for four months. CHARLES(CON): Construction of an ET station will take MUCH longer than docking together pre-fab ALPHA components. TOM PRO: Charles, this is true, just docking the modules together will take less time than the complete outfitting of the ET but the Extravehicular Activity (EVA) time for both Alpha and the ET spacestations will be about the same: about 350 hours for Alpha(according to CBS News 9-16-94). There will be much more interior outfitting required for the ET spacestation as compared to Alpha but 90 percent of this part of the conversion can take place after the ET is pressurized which makes the work involved much easier and faster since the astronauts can work without spacesuits. CHARLES(CON): Cost of one man in orbit is roughly $ 10 Million per day if he is relying on the Shuttle to live in during the interim. TOM PRO: Charles, the Russians are charging the Germans about $45 million to put one of their astronauts on the Mir spacestation for four months. I think that is a closer cost estimate. Charles, if we implemented Option C now it would still be completed before the Alpha spacestation, so useful science could begin earlier with Option C than with Option A. CHARLES(CON): I doubt it. TOM PRO: Charles, the estimated completion date for the $13 billion Option C spacestation was 1999; the estimated completion date for the $30 billion Alpha spacestation was 2003 (recently moved up to 2002). The dates are both NASA estimates so if they're in error, they're in error to the same degree. CHARLES(CON): This work is also dangerous with high risk of accident, congress does not like accidents. TOM: Charles, the ET outfitting work isn't anymore dangerous than assembling the Alpha spacestation in orbit. CHARLES(CON): Disagree. ET assembly is much more complex and much more dangerous than docking together pre-fab ALPHA modules. TOM PRO: Charles, the most complex part of the assembly will be attaching the airlock to the ET: the support structure for the airlock will have to be placed in position by astronauts while wearing spacesuits. Once the airlock is in place and the ET is pressurized the work will become much easier. CHARLES(CON): Crew fatigue and operator error will be big problems on a long duration assembly task using complex tooling. TOM PRO: Charles, I don't see crew fatigue as a problem if the astronauts stay in orbit. They can take their time outfitting the ET and can rest when they get tired. Much of the fatigue is from working in spacesuits which will be much less of a problem after the ET is pressurized. Freeing the astronauts from having to rely on the Space Shuttle to keep them in orbit will make a great difference also. CHARLES(CON): How does this compare to $ 150 Million to launch it [ET] on Energia ? TOM PRO: Charles, a Shuttle-Derived Heavy-Lift Vehicle may be comparable to Energia in cost. The cost figures I've been given on the Ground-Integrated Option C spacestation proposal were: $5 billion to construct the spacestation; $3 billion to develop the heavy-lift part CHARLES(CON): For $ 3 billion I can get you 20 Energia launches. Why bother with building a new heavy lifter ? TOM PRO: Charles, Energia's prices can't be beat, there's no doubt. I have no problem using Energia and it could do what a Shuttle-Derived Heavy-Lift Launch Vehicle can do, but there's no guarantee the price on Energia won't go up or that it will always be available to us. I would still be more comfortable having our own heavy lifter and after spending the initial $3 billion dollar investment to build an American heavy lift vehicle the cost per launch could probably get down in the range of Energia's cost. If we build Option C instead of Option A we'll spend $3 billion building a heavy-lift vehicle but we'll also be saving $17 billion by doing so. PRO: Charles, this is true, just docking the modules together will take less time PART 3 of the Space Conference's GREAT EXTERNAL TANK as SPACE STATION DEBATE DEREK HO(CON): It's worse than that. Each ET is not only 25000 lbs of aircraft-grade aluminum (if memory serves me right) but each contains about a 10% reserve of cryogenic fuels. Alex Gimarc (a Lt Col in the USAF last time I checked) did a nice study for the Space Studies Institute on ways to use the ET for space stations. As I understand it, NASA rejected the idea of keeping ETs in orbit for a number of reasons: the possibility of repeating the Skylab incident when their orbit(s) decay(s) TOM ABBOTT (PRO): Derek, this Skylab excuse has been repeated many times but is ridiculous. If you put a spacestation in orbit without a propulsion module is it the fault of the spacestation that it obeys natural laws and eventually falls back to Earth? No, it's the fault of the designers who decided to put it in orbit in that condition. ANY spacestation in low-Earth orbit will fall to Earth without a periodic reboost, ET or otherwise. DEREK HO (CON): You would think we should already have a structure in orbit using the ETs as building materials rather than the enormous amounts of money and time required from their current plan but I also think the engineers at NASA have some information the rest of us are lacking. TOM (PRO): Derek, you're implying that NASA knows something we don't know which keeps them from using the External Tank. You are assuming that NASA makes decisions logically. NASA acts the way the political wind blows which has nothing to do with logic. There is no secret showstopper which would keep the External Tank from being used as a spacestation or just about any other type of structure you can think of, for use in orbit. If there was a showstopper don't you think the fellows arguing the other side of this issue would have brought it up by now? Well, I take that back. There is one showstopper: Political decisions. There are no "technical" showstoppers. :) CHARLES RADLEY (CON): For $ 3 billion I can get you 20 Energia launches. Why CR> bother with building a new heavy lifter ? TOM ABBOTT (PRO): Charles, Energia's prices can't be beat, there's no doubt. I have no problem using Energia and it could do what a Shuttle-Derived Heavy-Lift Launch Vehicle can do, but there's no guarantee the price on Energia won't go up or that it will always be available to us. DEBATE MEDIATOR (Patrick Patriarca) I disagree here ... The important thing is to get A spacestation up. FAST CHEAP and GOOD. Right now the Energia is available. Use it. Regardless of what happens to Russia the ET is up there. period. Make sure it has a propulsion unit and Russia can do what it wants. With the $$$ saved instead of developing the Shuttle C use it on SSTO or gradually develop the HLV. OR use the $$$ to lift two or three Energiya's with ET'S on them. Whatever. We have the shuttle, Titan IV, Atlas 2 etc for supplies ... and the Proton so long as it is available. It's time we got the most bang for the buck. TOM ABBOTT (PRO): I would still be more comfortable having our own heavy lifter and after spending the initial $3 billion dollar investment to build an American heavy lift vehicle the cost per launch could probably get down in the range of Energia's cost. If we build Option C instead of Option A we'll spend $3 billion building a heavy-lift vehicle but we'll also be saving $17 billion by doing so. DEBATE MEDIATOR: IF it only costs 3 billion .... has ANY proposed rocket EVER come in on the projected cost estimate. None I know of. Use the Energiya 4 now. Unless you have the REAL POLITIK to pull off the Shuttle C (g). DEBATE MEDIATOR: Again I was unsure if Mr. Simpson was pro or con so I took a quess.. Quoting THOMAS SIMPSON to ALL regarding External Tanks in LEO: THOMAS SIMPSON: PRO (?) Question: if you put an ET in orbit with it vented (the valves open to space) and perhaps with a little tank of helium to help purge it, wouldn't the H2 an O2 tanks pretty well vent themselves clean, leaving nothing to possibly detonate or contaminate the interiors for future habitation?... DARRELL HOLLOWAY(CON): There is some difficulty in venting the ET once in orbit. While there is an oxygen vent valve which is still operable, and could be rigged to open on command from onboard sensors, you'd have to provide long term power to operate it and keep it open (spring loaded to shut position). The valves which connected the tank to the Orbiter (LO2, GO2, LH2, and GH2) are inoperable after separation of the Orbiter since the driving mechanism is on the Orbiter. The LH2 tank doesn't have a vent which can be operated like the LO2 does, once the hydrogen vent arm drops away at T-0 that valve closes for good (held open by the vent arm connection on the ground). So the LH2 side poses more of a problem. The helium tank for a purge would probable have to be tied in to some sort of logic circuit which would allow the vents to be closed while the tanks pressurized slightly with helium and then opened to vent the helium (and GO2/GH2 with it), and this would have to be repeated several (many) times to get the residual hydrogen out, aka pulse purging. Doable, but a technical chore, and not free. ANDY REYNOLDS (CON): That still doesn't answer the question: how do you get there? The SLC-6 facility has been partially converted to support launches of the LLV family of booster, the shuttle processing building is being converted into a payload processing area, and all of the shuttle related ground support hardware has been moved to KSC. So, even if you build your own shuttles, how do you plan to launch them? As for SSTO, well, they've not flown yet, so I'm not willing to start building a space station based on them as my supply/crew change vehicle. I talked to David Anderman about this, and he seems to be thinking of using Soyuz capsules/launchers to get to your polar orbiting station. You might tell him for me that it ain't gonna work. The Soyuz launcher is *very* close to maximum payload right now, and it's only going to 51.6 degrees. He quoted an inclination of 98+ degrees for the ET station, which means that the Soyuz is going to loose a whole lot of its lifting capacity. As it is the only man-rated booster the Russians are using (one has been planned for a *long* time, but never started), it doesn't look like you'll be riding that system either. I do have one other thing that I forgot to ask you in that first message. If I remember right, you said that the converted ET would be joined by other ET's later. Were you planning on getting these from your California shuttle? If not, you're in for some major engineering. The highest inclination orbit NASA is going to send a shuttle into will be the 51.6 degree orbit of the international space station. Even if they oblige you by dropping off the ET's in orbit, moving them from that inclination to the polar orbit of your station is going to mean some sort of orbital tug and a lot of fuel launches, as changing orbital planes is a rather fuel inefficient operation. That's not me talking, just Mother Nature's physics, plain and simple. I know that you're convinced that you can build this, and that it'll be just the greatest thing since sliced white bread and all. Problem is, it just ain't gonna be so, end of story. Believe what you want, reality always has the last laugh. PS: What you said to Andrea Berman might be true, but you got the $15 billion in *your* hip pocket? I don't, and I don't think anyone who's interested in doing such a mission does either.... TOM ABBOTT (PRO): A Proposal for the National Space Society's "Return to the Moon Initiative Tom Abbott November 27, 1994 Member: Oklahoma Space Alliance Chapter of the National Space Society I would like to submit a method to accomplish the National Space Society's "Return to the Moon Initiative," within the set time limit of ten years, at reasonable cost, and with no requirement to develop any new technology. Before I begin I would like to quote an article from a July 1993, issue of Popular Science about National Space Society Board Chairman Buzz Aldrin: "Should NASA scrap the current space station design, Aldrin has a second alternative: an original and patented design that could be up and flying in as few as two shuttle launches. His concept uses a modified Shuttle External Tank (ET) for living quarters, similar to the way Skylab used the remodeled second stage of a Saturn V rocket." It's great to have Buzz on the External Tank's side! The proposals: (proposal no. 1 is not a requirement to implement the Moonbase plan but it will have great benefits to our entire space program) *1. A call for a halt to work on NASA's $30 billion Option A (Alpha) spacestaton and to replacing it with NASA's $13 billion Option C spacestation, while emphasizing that the $17 billion saved MUST remain in the space program budget. The $30 billion Option A (Alpha) spacestation is in trouble already, even before the final design is set. According to sources, Boeing internal memos claim Alpha cannot be built unless more money is provided. Congress will not provide more money and may even cut more from the budget. If the Boeing memos are true we should recognize this reality early on and change our course as soon as possible. If we, as an organization (NSS), fail to discern reality and continue pushing Alpha we'll end up wasting several more years and Alpha will fall of its own weight anyway. Stubbornly hanging on to Alpha will not help our goals. There is a cheaper, better, faster, and bigger alternative: NASA's $13 billion Option C spacestation design. Option C was passed over in favor of Option A during the last redesign of the spacestation; much to the chagrin of many in the space community. NASA's $13 billion Option C spacestation is $17 billion cheaper than NASA's $30 billion Option A (Alpha) spacestation. NASA's $13 billion Option C spacestation would be completed (1999) 3 years before NASA's $30 billion Option A spacestation (2002). Implementing Option C during the upcoming spacestation vote would still enable Option C to be completed 2 years before Option A would have been completed. NASA's $13 billion Option C spacestation has ten times more habitable volume than NASA's $30 billion Option A spacestation. NASA's $13 billion Option C spacestation would be completely integrated on the ground before launch and would be ready to be occupied as soon as it reached orbit. NASA's $30 billion Option A spacestation would require assembly in orbit over a number of years. NASA's $13 billion Option C design would require converting the Shuttle Transportation System (STS) into a Heavy-Lift Vehicle (HLV) in order to launch Option C into orbit. The Option C habitation module would be bolted to the side of an External Tank and solid rocket boosters in the same manner as the Space Shuttle is connected. Three Space Shuttle Main Engines would be attached to the bottom of the habitation module (or the ET) and the Option C spacestation would launch itself into orbit, just as Skylab did 21 years ago. NASA's $13 billion Option C spacestation would require ONE launch to put a fully functioning spacestation in orbit. NASA's $30 billion Option A spacestation would require 32 launches to put all the equipment in orbit necessary to complete the spacestation. NASA's $13 billion Option C spacestation design incorporates the development of a Heavy-Lift Vehicle into its $13 billion cost. NASA's $30 billion Option A spacestation develops NO Heavy-Lift Vehicle. NASA's $13 billion Option C spacestation could accommodate several dozen people. NASA's $30 billion Option A spacestation could accommodate about 6 people. Development of NASA's $13 billion Option C spacestation would directly benefit he California Spacestation Project. The California Spacestation Project design is almost identical to NASA's Option C design (the only difference being California uses an empty ET as the habitation module; Option C uses a custom tank of similar size) so any developments could be shared between the two, which would result in cost savings for both. NASA's $30 billion Option A spacestation would provide no such benefits. NASA's Option C spacestation could accommodate the international community just as easily as could Option A; better, in fact. Most of the previous research and development for the Freedom and Alpha spacestations can be applied directly to the Option C spacestation. The majority of the money already spent on spacestation development will not go to waste by implementing Option C. NASA's $13 billion Option C spacestation is superior to NASA's $30 billion Option A (Alpha) spacestation in all respects. **************************************************** *2. Build an Option C-type Moonbase for about $5 billion in 5 years. NASA estimates the cost of the Option C spacestation habitation module at about $5 billion and estimates a cost of about $3 billion for the STS Heavy-Lift vehicle development. The California Spacestation Project estimates a cost of about $4 billion for their deluxe habitation module (they also estimate they can do a barebones ET spacestation for about $300 million) and a cost of about $3 billion to develop the HLV. Assuming the above figures are in the ball park, the scenario for the Moonbase goes like this: Instead of using the entire External Tank, as in the spacestation designs, the Moonbase design would use only the smaller oxygen tank of the ET as a habitation module. An intertank ring would be attached to the bottom of the oxygen tank to carry the engines and fuel tanks necessary for flying to and landing on the Moon. The ET Moonbase would be large enough to house 12 astronauts. It would be assembled and outfitted on the ground before launch and would be launched into Low-Earth orbit (LEO) just like the Option C spacestation: connected to the side of a fuel-carrying ET and solid rocket boosters. Four RL-10 rocket engines would be attached to the intertank ring to propel the Moonbase once in orbit. The RL-10's are some of the most reliable rocket engines ever produced and are the same engines the DC-X is using. The DC-X flight test data can be applied directly to the ET Moonbase since it will use the same engines and will land on the Moon in the same manner as the DC-X lands on Earth. To put the ET Moonbase on the Moon requires the launching of 80 tons of oxygen and hydrogen fuel to LEO to fuel the ET Moonbase for the trip. The 80 tons of fuel is enough to transport the ET Moonbase, along with 70 days worth of supplies for 12 people, to the Moon's surface. Launching the 80 tons of fuel into orbit will cost about $150 million? for one launch of a Shuttle-Derived HLV (or its Energia equivalent) or $1.5 billion if Titan IV vehicles (5 Titan IV's at $300 million each) are used (see how cost-effective developing a Heavy-Lift vehicle would be. Without a Heavy-Lift vehicle it would cost ten times as much to launch 80 tons of fuel to LEO: $150 million versus $1.5 billion. An HLV would pay back its development costs in short order). Total cost to implement the ET Moonbase will be about $7 billion: $5 billion for the oxygen tank/intertank conversion; $500? million for RL-10 developments (although DC-X development should help this cost); and about $1.5 billion (at most) to orbit the fuel. If the Option C spacestation is not implemented then the ET Moonbase will cost an additional $3 billion for development of the Heavy-Lift vehicle for a total cost of $10 billion. The tooling and infrastructure are already in place to handle and modify the External Tanks. The system technology needed to create a functioning platform already exists. ************************************** *3. Fund Single-Stage-to-Orbit vehicles and Earth/Moon transfer vehicles with the money remaining from the $30 billion Option A budget. If both the $13 billion Option C spacestation and the $7 billion ET Moonbase are implemented we will have around $10 billion left from Option A's former $30 billion budget (assuming we can retain all of it! Sounds like a job for NSS!). Most of the aerospace companies are estimating between $3 and $5 billion as the cost to build a Single-Stage-to-Orbit (SSTO) vehicle. With the $10 billion remaining from Option A's budget we should be able to fund several of these designs and an Earth/Moon transfer vehicle, too. By implementing NASA's $13 billion Option C spacestation, we can have a spacestation, Moonbase, Heavy-Lift vehicle and SSTO vehicle and develop the rudimentary infrastructure for the entire Earth/Moon system for the cost of one $30 billion Option A (Alpha) spacestation, alone. TOM ABBOTT (PRO): conversion base, how do you arrive at the $10 million per man per day figure? Are you going by NASA's claim that it costs $100,000 per hour for an astronaut in orbit? I bet the astronauts never see any of that money! :) CHARLES RADLEY(CON): I already posted the arithmetic, but here is again (in very round numbers): One Shuttle flight costs about $ 500 Million. Average crew: 5 persons Typical on orbit time: 10 days This gives 50 man-days for $ 500 Million. That works out at $ 10 million per person per day. You can trade of payload weight versus crew time. Using the EDO Orbiter( Endeavor is the only one) then you get 30 days, for max seven people, at a moderate payload penalty, plus some increased cost. TOM (PRO): Charles, ideally, the Shuttle would drop the conversion crew off at the ET and could then return to Earth leaving the work crew in orbit. CHARLES(CON): NASA safety rules do not permit this. A crew cannot be left in orbit without means of immedaite emergency return to Earth. TOM (PRO): The Russians use about 3 tons of consumables each month on the Mir spacestation. A Space Shuttle could supply these quantities of supplies for little or no extra cost just by using the excess capacity of the Shuttle (the Shuttle has never lifted its maximum rated tonnage CHARLES(CON): So you expect NASA to make an exception in your case.... TOM (PRO): to orbit, of course, lifting to the Russian Mir orbit cuts the Shuttle's tonnage by about 7 tons). Or we could use a Russian Proton to put a four month supply of consumables in orbit with one $60 million launch. Well that beats $ 500 M. TOM (PRO): Charles, "us" is America. I'm sure the Russians will deliver as long CHARLES(CON): That is a narrow view. I have a more global perspective. "us" is anybody with the means and / or motivation to get into space. TOM (PRO): as they are paid. There's no guarantee some internal Russian problem won't cut us off from their services. I just like to hedge my bets. Losing access to CHARLES(CON): And there's not guarantee we will lose access to American services. TOM (PRO): Russia's Energia wouldn't necessarily require a civil war it could be caused by something as simple as an anti-space party getting elected. CHARLES(CON): There is no anti-space party in Russia. The space program is a cash cow for them, it is a national priority. Cannot say the same thing about the USA, however. The only thing keeping NASA going right now is cooperation with the Russians. The new US congress is less likely to support this philosophy. The new US congress is more likely to emphasize military program versus space programs. It is wise to use "dual sourcing" when buying anything. Use the cheapest carriers (in this case Russian) but retain options on an alternate supplier, eg US or European launch services. BTW, the Energia core vehicle is much bigger than an ET, and could also be configured to achieve orbit. To: LYNNDEL HUMPHREYS From: MIKE ZELESKI Public LYNNDEL HUMPHREYS (PRO): Dumping the fuel overboard into space is no problem. But, considering the difficulty of getting the fuel up there to begin with the difficult problem would be to transfer any excess fuel to a reserve fuel holding receptacle. doubt if the conservation of fuel will be a concern. MIKE ZELESKI (CON): That kettle is going to Boil for a while until we get to opening it. That is going to put the ET structure under a lot of pressure in a direction that it was not originally designed to resist. Outwards vs downwards... The O2 tank does not worry me as much as the H2 tank does, as it does not have a simple vent-purge valve like the O2 tank does and it also boils at a much lower temp. LYNNDELL: (PRO): Also, a spacestation does not necessarily have to be built or operated by astronauts. It could be automated. MIKE(CON): Automation is only good for repetitive, mass production tasks or very specialized tasks. Automation also breaks down and needs maintenance. I remember that a Auto Company surveyed it's automation a few years ago and found that it had to increase it's maintenance staff by 40% of number of staff that the automated machinery replaced. So all automation does is get rid of some of the lower level jobs and replace them with highly trained techs... It would also take a lot of shuttle flights to haul the equipment needed to remanufacture ET's into structural material and you also want to automate the process completely... MIKE ZELESKI(CON): Partial outfitting is not comparable at all to a complete refurbishment or complete outfitting. TOM ABBOTT (PRO): Mike, it's the same process whether it's partial or complete outfitting. MIKE ZELESKI(CON): In effect the difference is like trying to rebuild a complete house at once vs just remodeling a room at a time... The one you can live with some inconvenience in while your doing it and the other needs a construction shack or another home and excludes all other work until it quite close to being ready. TOM ABBOTT (PRO): Mike, there is no difference between living in a partially completed Freedom module or a partially completed External Tank. The ET does not exclude all other work until it is quite close to being ready, as you state. Once the ET is pressurized, a person could live inside it for 5 months, WITHOUT any air recycling equipment, before carbon dioxide levels reached dangerous levels. Five people could live inside for one month (the ET holds 5 man-months of breathable atmosphere). The ET can be lived in as soon as it is pressurized. MIKE ZELESKI(CON): Let's be a bit more practical Tom... TOM ABBOTT (PRO):Mike, you have yet to show me where I've been impractical. The Freedom spacestation's airlock door and the External Tank's access hatch are within a few inches of being the same size. NASA seemed to think they could outfit Freedom this way, what would prevent the same method from being used on the External Tank? MIKE ZELESKI (CON): Obviously everything that is larger than the "Hatch" can be installed inside of the module before it is sealed up for launch. Also quite a bit of the materials that are needed to finish the job can be stuck inside of it before it is launched reducing the amount that would need to be transferred to it from another spacecraft... TOM ABBOTT (PRO): Mike, the equipment to outfit the Freedom modules would not have been stowed inside the module before launch. The reason the Freedom modules had to be partially assembled in orbit was because they were too heavy to launch fully equipped. Unassembled equipment stowed inside a Freedom module will weigh as much as assembled equipment. What's the point of putting unassembled equipment inside a Freedom module? If the Shuttle could lift the load, wouldn't you install the equipment while the Freedom module is on the ground and save yourself the trouble of doing it in orbit? That's one reason the Alpha spacestation module was reduced from Freedom's 45 ft length down to 27 ft: so the Alpha module would weigh less and could be launched fully equipped (although there is doubt even the smaller Alpha modules can be launched fully outfitted). MIKE ZELESKI (CON): Hatch sizes are not comparable in this respect with the ET vs Space Station Module in mind. Shape and direction are also very important considerations when you need to pass massive/large/long/unusualy shaped objects through such a passage... TOM ABBOTT (PRO):Mike, I don't follow this argument. The ET and the Alpha module both have similar sized hatches. Both hatches are located on the ends of their respective modules. What makes one OK and the other not OK? MIKE ZELESKI (CON): If you had spent some time on a submarine or any other type of working ship the above would be very obvious to you... Trying to reuse a ET is like trying to convert a fuel bunker into a berthing space, compared to dropping a converted mobile home somewhere on deck and bolting it down... TOM ABBOTT (PRO):Mike, there's a difference between hydrogen and oxygen fuel and fuel oil. If the fuel tank can perform the same function as the mobile home and is billions of dollars cheaper does it make sense to build mobile homes (very small mobile homes)? Tests have shown a space suited astronaut can remove the bolts securing the access hatches on the aft ends of both the hydrogen and the oxygen tank of the External Tank and can move into and out of it freely. MIKE ZELESKI(CON): Oh I'm certain that a astronaut can get into and out of it, but there has to be a easier to use entrance/exit than a just a bolt on plate. TOM ABBOTT (PRO): Mike, you don't seriously think we're going to bolt and unbolt the access hatch every time we go in or out of the ET, do you? What we're really going to do is make it easy on ourselves and fasten an airlock to the ET just as is done on the Alpha spacestation or the Space Shuttle. MIKE ZELESKI (CON): Even if you were to simply bolt 2 tanks end to end then some sort of collar and structural support would have to be added to the assembly. TOM ABBOTT (PRO): Mike, I'm not proposing bolting two ET's end to end at this time but it could be done. And if you did bolt them together you would still need an airlock to get in and out. MIKE ZELESKI or Darrell Holloway (CON): Even if it [ET] were launched in a condition that did not pollute the space around it with tiny particles of foam... TOM ABBOTT (PRO): Darrell, I think I've covered the methods to take care of the insulation problem, previously. MIKE ZELESKI (CON): A lengthily rebuttal should go here, but all of the methods that I have seen to date are all impractical or rather unworkable... TOM ABBOTT (PRO): Mike, it's easy to say something is "impractical or rather unworkable" if you don't get specific. A lengthy rebuttal should go here instead. But just to add a little: Martin Marietta, the ET's producer, is currently working on two new types of External Tank insulation: one of these peels off like a banana peel; and the other doesn't come off at all, even in space. I wonder why they're doing that? :) MIKE ZELESKI (CON): About time, they should of been working on that a long time ago... TOM ABBOTT (PRO): Mike, does easily removed insulation make the ET viable in your eyes? MIKE ZELESKI (CON): I like the idea that the ET could be possibly be reused in space but I think that the uses that it is put to and the number of them that are used is going to be way less than you think due to some practical considerations that we are not even yet aware of now... TOM ABBOTT (PRO): "due to practical considerations that we are not even yet aware of now..." is a nonargument. Should we give up on the ET spacestation concept because of some vague hypothetical problem you're not even yet aware of? MIKE ZELESKI(CON): > That kettle is going to Boil for a while until we get to opening it. TOM ABBOTT (PRO): According to a study undertaken at the direction of the External Tank Project Office, Marshall Space Flight Center, NASA, Huntsville, AL, "ET Inspection On-Orbit," and I quote: "For manned ET inspection, the pressure in the tanks is decreased to less than 5 psig. There are three ways to accomplish this: (1) through the Orbiter's fill and drain valves, (2) through the Orbiter's engines and (3) through the ET vent and relief valves. The first method, through the fill and drain valves, is recommended. The second method has the disadvantage that the vented hydrogen could affect the engine unfavorably. The third method requires modifications to the ET. Depressurizing through the fill and drain valves reduces pressure to a satisfactory level within the short time of 20 minutes. However, the torque generated by the effluent gases and liquids requires the RCS to offset this torque. This 20 minute time limit applies even for the maximum total residuals (34,000 lbs) considered. Sufficient offsetting torque is available from the aft RCS, with the RCS propellant requirements of 1,066 lbs for the baseline case. TOM ABBOTT PRO Mike, it's the same process whether it's partial or complete outfitting. MIKE ZELESKI (CON): The process is the same but it is still not comparable at all... TOM ABBOTT (PRO):Mike, there is no difference between living in a partially completed Freedom module or a partially completed External Tank. The ET does not exclude all other work until it is quite close to being ready, as you state. Once the ET is pressurized, a person could live inside it for 5 months, WITHOUT any air recycling equipment, before carbon dioxide levels reached dangerous levels. Five people could live inside for one month (the ET holds 5 man-months of breathable atmosphere). The ET can be lived in as soon as it is pressurized. MIKE ZELESKI (CON): Providing just a breathable atmosphere is not at all a livable situation... A Heating and Cooling system with a circulator fan also would have to be provided. If that has to be added first then adding a air scrubber is just another small step... Think... It is just as difficult to work in Parka & Gloves or wear thermal protection as working in a space suit would be. TOM ABBOTT (PRO):The Freedom spacestation's airlock door and the External Tank's access hatch are within a few inches of being the same size. NASA seemed to think they could outfit Freedom this way, what would prevent the same method from being used on the External Obviously everything that is larger than the "Hatch" can be installed inside of the module before it is sealed up for launch. MIKE ZELESKI(CON): The size of the Airlock is also very important... It's Length and Volume are very important considerations... A bigger airlock would weigh a lot more and take longer to cycle... TOM ABBOTT (PRO):Mike, the equipment to outfit the Freedom modules would not have been stowed inside the module before launch. The reason the Freedom modules had to be partially assembled in orbit was because they were too heavy to launch fully equipped. Unassembled equipment stowed inside a Freedom module will weigh as much as assembled equipment. What's the point of putting unassembled equipment inside a Freedom module? If the Shuttle could lift the load, wouldn't you install the equipment while the Freedom module is on the ground and save yourself the trouble of doing it in orbit? MIKE ZELESKI (CON): Think about how you can drywall one side of a wall in a house before you do the plumbing and wiring inside of that wall... However in space I suspect that it would be lightweight semi-rigid plastic sheeting that would not weigh very much vs what it would hide... In the ET you would have to haul both sides that wall and also the equivalant of studs... TOM ABBOTT (PRO):That's one reason the Alpha spacestation module was reduced from Freedom's 45 ft length down to 27 ft: so the Alpha module would weigh less and could be launched fully equipped (although there is doubt even the smaller Alpha modules can be launched fully outfitted). MIKE ZELESKI (CON): Really? I thought that was due to Shuttle "C" going down the tubes... TOM ABBOTT (PRO): Hatch sizes are not comparable in this respect with the ET vs Space Station Module in mind. Shape and direction are also very important considerations when you need to pass massive/large/long/unusualy shaped objects through such a passage... Mike, I don't follow this argument. The ET and the Alpha module both have similar sized hatches. Both hatches are located on the ends of their respective modules. What makes one OK and the other MIKE ZELESKI (CON): One can have all of those oversized items already installed, the other would not. So the Alpha Airlock can be a built lot smaller and therefore lighter than the ET airlock. Also since the modules are very likely to be mated to another module or a service structure so some modules could use a much simpler hatch structure & lifeballs instead of having a full airlock... Actually using a ET in any capacity makes a lot more sense only after a lot more of the space station is already assembled and manned. Then Suit-Time and On-Site-Labor would be a lot more cost effective. The need for a storage room or a unimproved auxiliary space would then be a lot greater. Also you would have a redundant structure to use in case of a leak or blowout... MIKE ZELESKI (CON): Trying to reuse a ET is like trying to convert a fuel bunker into a berthing space, compared to dropping a converted mobile home somewhere on deck and bolting it down... TOM ABBOTT (PRO):Mike, there's a difference between hydrogen and oxygen fuel and fuel oil. If the fuel tank can perform the same function as the mobile home and is billions of dollars cheaper does it make sense to build mobile homes (very small mobile homes)? MIKE ZELESKI (CON): I guess that you completely missed the point of this analogy. So I'm going to drop it... TOM ABBOTT (PRO):Mike, does easily removed insulation make the ET viable in your MIKE ZELESKI (CON): More viable than what we have now but still much more difficult to convert than completing a nearly finished module that you can move into right away. TOM ABBOTT (PRO):Mike, "due to practical considerations that we are not even yet aware of now..." is a nonargument. Should we give up on the ET spacestation concept because of some vague hypothetical problem you're not even yet aware of? MIKE ZELESKI (CON): A good engineer simply states this as an appropriate application of Murphy's law and the KISS factor. The more complex the procedure or structure the more difficult it is to complete it. Also it is a lot more likely that a unknown problem may appear while it is being completed. This is not a "nonargument" but a fact of life. Let's put it this way, if your grand idea fails, you only trash your reputation, if they fail it is quite likely that some people will die and NASA will probably end up being completely dismantled. TOM ABBOTT (PRO):According to a study undertaken at the direction of the External Tank Project Office, Marshall Space Flight Center, NASA, Huntsville, AL, "ET Inspection On-Orbit," and I quote: MIKE ZELESKI (CON): I read it and you missed the bit about how the drain and fill valves needs a EVA to open them. They are after all operated externally from the Orbiter... "->offsetting torque is available from the aft RCS, with the RCS "->propellant requirements of 1,066 lbs for the baseline case. That is a big chunk of the Shuttle's RCS propellants if the shuttle RCS computer is programmed to allow automatic station keeping with the tank still intact... If not then the RCS would have to be fired manually using significantly more propellant. I have yet to examine if the ET would interfere with firing the OMS engines. I have the definite feeling that it may... (Quoting Tom Abbott to Charles Radley ) TOM ABBOTT (PRO):conversion base, how do you arrive at the $10 million per man per day figure? Are you going by NASA's claim that it costs $100,000 per hour for an astronaut in orbit? I bet the astronauts never see any of that money! :) CHARLES RADLEY (CON): I already posted the arithmetic, but here is again (in very round numbers): TOM ABBOTT (PRO): Charles, many Shuttle flights don't carry a full complement of astronauts. Supposing NASA was amenable to the idea, an ET construction crew could fill the extra places on the Shuttle and could fly to orbit and work on converting the ET spacestation for the cost of their salary and the cost of the food, water and air they use. Ten million dollars per person per day wouldn't apply. If NASA doesn't like the idea, we pay the Russians $45 million per person for a four month stay on Mir. Or we buy a $10 million Soyuz vehicle and a $300 million habitation module. Charles, ideally, the Shuttle would drop the conversion crew off at the ET and could then return to Earth leaving the work crew in orbit. CHARLES RADLEY (CON): NASA safety rules do not permit this. A crew cannot be left in orbit without means of immediate emergency return to Earth. TOM ABBOTT (PRO):Charles, I'm not proposing leaving a crew stranded in orbit. They would certainly need a return vehicle. Got any Soyuz for sale? :) The Russians use about 3 tons of consumables each month on the Mir spacestation. A Space Shuttle could supply these quantities of supplies for little or no extra cost just by using the excess capacity of the Shuttle (the Shuttle has never lifted its maximum rated tonnage CHARLES RADLEY (CON): So you expect NASA to make an exception in your case.... TOM ABBOTT (PRO):Charles, it would probably depend on who is building the ET spacestation. The point is it's possible to carry extra tonnage on the Shuttle essentially free since the Shuttle is going to orbit anyway. The heaviest payload the Shuttle has put in orbit weighed 17 tons, but the Shuttle has the potential to put about 30 tons in orbit. Whether NASA takes advantage of this factor is up to them. The California Spacestation Project will certainly take advantage of it with their Shuttles, if the opportunity presents itself. ...into orbit, of course, lifting to the Russian Mir orbit cuts the Shuttle's tonnage by about 7 tons). Or we could use a Russian Proton to put a four month supply of consumables in orbit with one $60 million launch. CHARLES RADLEY (CON): Well that beats $ 500 M. TOM ABBOTT (PRO):Charles, $500 million would be the cost for a dedicated Shuttle mission. If a regularly scheduled Shuttle's excess cargo capacity is used to supply the spacestation it would cost much less--the launch costs are already paid. Charles, "us" is America. I'm sure the Russians will deliver as long CHARLES RADLEY (CON): That is a narrow view. I have a more global perspective. "us" is anybody with the means and / or motivation to get into space. TOM ABBOTT (PRO):I wouldn't call it a narrow view. I would call it a prudent view. We should never put ourselves in the position of being dependent on anyone. We are not in that position right now with the Alpha spacestation. We are not masters of our own destiny. Russia wouldn't necessarily require a civil war it could be caused by something as simple as an anti-space party getting elected. CHARLES RADLEY (CON): There is no anti-space party in Russia. The space program is a cash cow for them, it is a national priority. TOM ABBOTT (PRO):Charles, the current Alpha international spacestation arrangement is vulnerable to many things. Our own State Department could use the spacestation program to punish Russia for misbehavior. The Russians are doing some shooting right now; maybe Warren Christopher won't like that. Bosnia has the potential to adversely affect our (U.S.) space program goals (mainly by dragging Russia into the conflict). The Kazakhs aren't happy with Russia and they control the Baikonur launch facility which will launch many Alpha spacestation components and without which Alpha will never be built. We should cooperate with all countries including Russia but we should also be able to go it alone if we have to. CHARLES RADLEY (CON): The only thing keeping NASA going right now is cooperation with the Russians. TOM ABBOTT (PRO):Charles, I don't think NASA is going anywhere right now, with Russia or without them. CHARLES RADLEY It is wise to use "dual sourcing" when buying anything. Use the cheapest carriers (in this case Russian) but retain options on an alternate supplier, eg US or European launch services. TOM ABBOTT (PRO):Charles, that's what I've been saying. We need to have options. CHARLES RADLEY (CON): BTW, the Energia core vehicle is much bigger than an ET, and could also be configured to achieve orbit. TOM ABBOTT (PRO):Charles, Energia is a "little" bigger than an ET. I've been waiting for the Russians to put an Energia core in orbit. What do they say about it? PART 4 (the final part) of the Space Conference's GREAT EXTERNAL TANK as SPACE STATION DEBATE ANDY REYNOLDS (CON): It is very good to have an estimate of how much it would cost to refurbish the SLC-6 facility, but that still doesn't answer what I said: It is currently being planned for use on other launcher operations, i.e. the LLV, and that *both* NASA and the AF had dropped their plans to use the facility a good while before Challenger. The latter is the real killer to your proposal. TOM ABBOTT (PRO):Andy, another launch facility is being built at Vandenburg for the smaller launch vehicles. Here's what Lt. General Forrest McCartney, USAF (Retired), former director of the Kennedy Space Center and commander of USAF Space Division said about closing the Shuttle Launch Complex, "It (SLC-6) really wasn't mothballed; they just walked away from it. I think it was for two reasons: one was emotionalism because the Air Force desperately wanted to retain Expendable Launch Vehicles...the other was that NASA was in such total disarray (after Challenger)... The nation was in such a shock. I'd say that the need went away and the emotion of NASA and the Air Force was such that they just walked away from it." How does General McCartney's statement square with your assertion that NASA and DOD's mothballing of SLC-6 is the real killer of the California Spacestation Project's plans to launch from Vandenburg? ANDY REYNOLDS (CON): The reason that SLC-6 was dropped as a shuttle launch site was that, when the folks who'd be using it got to looking, they found that just about any way they might shoot a shuttle off, they'd be coming close to, if not actually overflying, populated areas. TOM ABBOTT (PRO):Andy, a Shuttle launching south out of Vandenburg doesn't overfly any populated land and once it clears the coastline it doesn't overfly land until it reaches Antarctica. Look at a map. ANDY REYNOLDS (CON): The AF also did something else that is sort of odd for them: they listened to some of their environmental advisors. These folks had pointed out that the conditions at Vandenburg would lead to some very tight weather-related launch criteria. Seems that the SLC-6 facility is located so that the exhaust of the SRB's can combine with local weather (in the form of moist air) to form an acid fog. This wouldn't be something that would just both the local wildlife either. Because the site is semit-protected, the wind doesn't stir up the air in this area often, meaning that the fog could be *very* acid, enough to cause maintenance problems with corrosion of the equipment at the pad. (the above comes from a review of the launch facility published a couple of years ago in that tree-hugger journal "Aerospace America", so, yes, I do put some small stock in this.) TOM ABBOTT (PRO):Andy, do you know of any Federal construction project, especially one in California, that isn't required to do an environmental impact study before construction is allowed to begin? The weather at Vandenburg has to be taken into consideration, just like in a Florida Shuttle launch, but this won't prevent the California Spacestation Project from carrying out their plans. ANDY REYNOLDS (CON): So, saying that it will only cost "X number of dollars" to refurbish SLC-6 is nice, but it doesn't move your idea any closer to reality, as that figure probably doesn't include building some place for Lockheed to conduct its launches, or answer the above environmental problem. TOM ABBOTT (PRO):Andy, as I said, other launch facilities will be built at Vandenburg. The plans are already underway. ANDY REYNOLDS (CON): Bottom line: I ain't puttin' any money on seeing your idea fly. Sorry. Andy. TOM ABBOTT (PRO):Andy, so I guess we shouldn't send you any fundraising letters, then. --------------------- DEREK HO (CON): It's worse than that. Each ET is not only 25000 lbs of aircraft-grade aluminum (if memory serves me right) but each contains about a 10% reserve of cryogenic fuels. Alex Gimarc (a Lt Col in the USAF last time I checked) did a nice study for the Space Studies Institute on ways to use the ET for space stations. As I understand it, NASA rejected the idea of keeping ETs in orbit for a number of reasons: the possibility of repeating the Skylab incident when their orbit(s) decay(s) TOM ABBOTT (PRO): Derek, this Skylab excuse has been repeated many times but is ridiculous. If you put a spacestation in orbit without a propulsion module is it the fault of the spacestation that it obeys natural laws and eventually falls back to Earth? No, it's the fault of the designers who decided to put it in orbit in that condition. ANY spacestation in low-Earth orbit will fall to Earth without a periodic reboost, ET or otherwise. DEREK HO (CON): You seem to miss the point Tom. I would LOVE it if we could have used the ETs to provide a structure to build our spacestation on. I believe that NASA, given sufficient motivation and ingenuity, could have done so. However, there are valid engineering and political reasons against the ET-spacestation concept. TOM ABBOTT (PRO): Derek, what might those valid engineering and political reasons be? DEREK HO (CON): The Skylab example is one of them -- we would have had an international incident complete with diplomatic demarches if Skylab had caused any massive property damage or, God forbid, killed someone. Putting a large structure in orbit with no control elements and no assurance of being able to adjust its orbit periodically would be criminal. TOM ABBOTT (PRO): Derek, I agree that putting a large structure in orbit with no control elements is criminal but that applies to ANY spacestation in orbit. The External Tank is no more or less affected by this argument than any other type of structure in space. It's certainly no argument against using External Tanks. The solution: put a reboost system on it. DEREK HO (CON): You would think we should already have a structure in orbit using the ETs as building materials rather than the enormous amounts of money and time required from their current plan but I also think the engineers at NASA have some information the rest of us are lacking. TOM ABBOTT (PRO): You're implying that NASA knows something we don't know which keeps them from using the External Tank. You are assuming that NASA makes decisions logically. NASA acts the way the political wind blows which has nothing to do with logic. DEREK HO (CON): No I'm not assuming NASA makes all its decisions logically. I am also not implying NASA knows more than we do about the ET, I'm SAYING it. TOM ABBOTT (PRO):I'm disagreeing with you then, Derek. DEREK HO (CON): Have you considered an ET-station from ALL grounds? TOM ABBOTT (PRO):Derek, I believe so. DEREK HO (CON): When I spoke to people at NASA about the concept, I kept hearing problems with the idea that I hadn't thought of or heard before, e.g., the tank insulation would outgas and is poisonous to humans in vapor form, cryogenic fuels in the tank are volatile and have a high probability of causing a catastrophic explosion if left in an unshielded ET for any great length of time, etc. TOM ABBOTT (PRO): There is no secret showstopper which would keep the External Tank from being used as a spacestation or just about any other type of structure you can think of, for use in orbit. If there was a showstopper don't you think the fellows arguing the other side of this issue would have brought it up by now? DEREK HO (CON): No I don't Tom. I have great respect for Alex Gimarc but we in the advocacy community do NOT have all the information at our hands. DEBATE MEDIATOR I would ask since WE are paying for NASA and most all these studies why we would not have ALL the information at our hands ...unless the info. threatens national security we have every right to access about a program we (the taxpayers) are funding. TOM ABBOTT (PRO): Derek, what makes you think that? Many of the studies I use were done by NASA. Many of the External Tank advocates work or have worked for NASA. The External Tank spacestation concept has been studied more than any other piece of space hardware in the entire history of the space program. DEREK HO (CON): Sometimes the information we DO have is inaccurate or misleading -- James Oberg presents a great example of this in some of his columns. I am as pessimistic about NASA's current structure as anyone I know; like Jerry Pournelle, I sometimes think it ought to be torn down and rebuilt from the ground up. I think you make a mistake, however, in denying the fact that there may be very good reasons for not doing something that seems to be a good idea to us. TOM ABBOTT (PRO):Derek, I'm still waiting for someone to point those very good reasons out to me. (Quoting Andy Reynolds to Tom Abbott) ANDY REYNOLDS: I read your post regarding "drop Alpha/Build Option C". If you're serious about this, why even bother with SLC-6? If NASA's going to build the Option C station like you want, why not just save the cost of refurbishing SLC-6 and use KSC? TOM ABBOTT (PRO):Andy, launching from KCS is being considered. Of course, that would depend a lot on NASA. Launching from Vandenburg also has advantages over KCS. Both launch sites have unique capabilities. ANDY REYNOLDS: As to what the Air Force chappie had to say, well, when was that comment made? TOM ABBOTT (PRO):Andy, I got that quote from the British Interplanetary Society's "Spaceflight" publication, November 1994, p. 378. ANDY REYNOLDS (CON): NASA moved out some of the processing hardware for the shuttle fleet that was at Vandenburg last year so that they could expand the capacity of the shuttle processing facility at KSC. Want to replace it, or ask NASA to bring it back? TOM ABBOTT (PRO):Andy, either way will work. ANDY REYNOLDS (CON): As for the new facility for launching small boosters, the last I saw about the LLV was a nice picture and story in "Space News" about the project. The picture caption told how the mock-up stack that they were testing was "mounted on an adapter on the former SLC-6 shuttle launch pad", which was to be used for the actual launch. I've neither heard nor read anything about a new launch site at Vandenburg for this or any other launcher. TOM ABBOTT (PRO): From an article in the National Space Society's "Ad Astra" magazine, July/August 1994, p. 11: "The California Commercial Spaceport will design, develop, build, operate and maintain the California Commercial Spaceport. Having sold 20 percent of its stock to raise the required $400,000, the company is now working on getting bonds and joint ventures set up. Already CCSI has 22 contractors working to build the launch facility and an integrated processing facility. The launch facility will be a "universal" launch pad, built from scratch, at Cypress Ridge, a site about three kilometers south of Launch Complex 6. Severo hopes to have the launch site operational in November 1995, at an estimated cost of around $6 million. In April, Motorola and McDonnell Douglas jointly announced an Iridium launch contract award that involved eight Delta launches, each carrying five satellites, for a total of 40 satellites. The first Delta launch is expected in September 1996. This barely scratches the surface of what is happening around Vandenburg, but it does give a taste of what is needed to make a spaceport a reality." DEBATE MEDIATOR I was unable to find out the last name of the following "THOMAS" individual ...my apologies ... THOMAS: helium purging would clean them (the external tanks)right up. Am I correct? TOM ABBOTT (PRO): Tom, you are correct. The small amount of residual fuel remaining in the ET after it is detached from the Shuttle would be vented in the manner you describe. THOMAS: I asked because I gather that cleaning out the tanks would be a problem if you were using one of those toxic-as-hell tanks using a high-energy fuel and oxidizer, as does Ariane. TOM ABBOTT (PRO): Thomas, are you talking about the aluminum/lithium tanks? THOMAS: Also, wasn't that a problem with that tank-based station that one of the Gemenis experimented with back in the '60s? TOM ABBOTT (PRO): Thomas, the only rocket fuel tank-based station I know of was Skylab. At one time Skylab was to be outfitted in orbit after it had been used to carry fuel for the Saturn V rocket. The problem with this was the insulation for the fuel tank was located on the inside of the tank and it was felt that fuel would be absorbed by the insulation and would make it impossible to maintain an uncontaminated environment inside the converted spacestation. Fortunately, the External Tank's insulation is located on the outside of the tank which eliminates this particular problem. TOM ABBOTT (PRO):MESSAGE TO ALL California Space Station Project If you are interested in helping the California Space Station Project succeed you can make your support known to Congressman Newt Gingrich's staff person for space, Rob Hood at 202-225-4501; Congressman David Drier's staff person, Katherine Kless at 202-225-2305; and Congressman Dana Rohrabacher's staff person, Tim Kyger at 202-225-2415. Gene Meyers, a proponent of the California Space Station Project has been working with these people and they are very interested in the California Project. The purpose of these calls and letters in support of the California Space Station Project is not aimed at convincing these staffers of the benefits of the California Space Station Project or the value of private enterprise in space in general, because they are convinced. Rather, the calls and letters would enable the staffers to show the ones that need convincing that there is a lot of support for this approach. If you are not familiar with the California Space Station Project or the potential of using Space Shuttle External Tanks in orbit you can get Gene Meyers book "ET-Solutions: Detroit's Competitive Secret" which is a thorough explanation. If the book isn't available at your local book store you can get one directly from Gene for $15. Gene Meyers P.O. Box 814 West Covina, CA 91793 (Quoting Tom Jolly to Jack Sargeant) TOM JOLLY: As far as external tanks being cheap, I favored the idea originally, also. But eventually one fellow (who's name I forget) pointing out that eventually you have to put all the furnishings in orbit, too, and subsequently spend a few thousand hours on EVA's, to which he added, why not do all the building here on earth, and just launch a fully furnished ET? At a fraction of the cost of building it in orbit. TOM ABBOTT (PRO): Putting all the furnishings in after the ET reaches orbit would still be cheaper than the $30 billion Alpha spacestation and there is no guarantee that the Alpha modules won't have to be partially outfitted in orbit, anyway. NASA is still not sure they can launch a fully equipped Alpha module. That's why they're trying to build aliminum/lithium ET's and are considering not putting parachutes on the solid rocket boosters just so they can cut enough weight to launch an Alpha module. "Doing all the building of the spacestation here on Earth and then launching a fully furnished ET" spacestation into orbit is exactly what NASA's Option C spacestation and California's Spacestation Project would do. This is the best of all the options. TOM ABBOTT (PRO): The Freedom spacestation's airlock door and the External Tank's access hatch are within a few inches of being the same size. NASA seemed to think they could outfit Freedom this way, what would prevent the same method from being used on the External Tank? MIKE ZELESKI (CON): The size of the Airlock is also very important... It's Length and Volume are very important considerations... A bigger airlock would weigh a lot more and take longer to cycle... TOM ABBOTT (PRO): Mike, the ET spacestation would use the same size airlock as Freedom or Alpha. ....that's one reason the Alpha spacestation module was reduced from Freedom's 45 ft length down to 27 ft: so the Alpha module would weigh less and could be launched fully equipped (although there is doubt even the smaller Alpha modules can be launched fully outfitted). MIKE ZELESKI (CON): Really? I thought that was due to Shuttle "C" going down the tubes... TOM ABBOTT (PRO):No, it didn't have anything to do with Shuttle-C, Mike. MIKE ZELESKI (CON): A good engineer simply states this as an appropriate application of Murphy's law and the KISS factor. TOM ABBOTT (PRO): You mean a good engineer should think we shouldn't do something because there are unknowns involved? If we follow that reasoning we would never do anything. MIKE ZELESKI (CON): Again you missed my point, a prudent engineer would on having as much data as possible on hand before he/she precedes on a new design. Would you please admit that neither of us know enough to *PROVE* it can be done. The more complex the procedure or structure the more difficult it is to complete it. Also it is a lot more likely that a unknown problem may appear while it is being completed. This is not a "nonargument" but a fact of life. TOM ABBOTT (PRO): You say because of "unknown problems, which you aren't aware of yet" we should not try to use External Tanks in space. Do you consider this a legitimate reason for abandoning the idea of using ET's? You could apply this kind of "reasoning" to not build Alpha or anything else. If we let unknowns stop us we would still be cowering in the caves. MIKE ZELESKI (CON): Let's put it this way, if your grand idea fails, you only trash your reputation, if they fail it is quite likely that some people will die and NASA will probably end up being completely dismantled. TOM ABBOTT (PRO): Well, first of all, it's not my idea but it is pretty grand. And second, an External Tank spacestation is as safe as any other kind of spacestation. MIKE ZELESKI (CON): You have made it yours by debating it so forcefully... --------- MIKE ZELESKI (CON): I read it and you missed the bit about how the drain and fill valves needs a EVA to open them. They are afterall operated externally from the Orbiter... TOM ABBOTT (PRO): Mike, according to the Air Force University ASSET ET study, all activities to vent the fuel are accomplished from inside the Orbiter. No EVA would be required. MIKE ZELESKI (CON): If the Orbiter and ET are modified slightly. ...offsetting torque is available from the aft RCS, with the RCS propellant requirements of 1,066 lbs for the baseline case. MIKE ZELESKI (CON): That is a big chunk of the Shuttle's RCS propellants if the shuttle RCS computer is programmed to allow automatic station keeping with the tank still intact... If not then the RCS would have to be fired manually using significantly more propellant. TOM ABBOTT (PRO): Mike, the RCS propellant will not be a problem. MIKE ZELESKI (CON): By what reference do you base this? What is the percentage of the amount onboard that this is? I have yet to examine if the ET would interfere with firing the OMS engines. I have the definite feeling that it may... MIKE ZELESKI (CON): Obviously you do not understand that if the OMS cannot be fired then the Orbiter would reenter at the end of that first orbit. Period, there is no argument possible about it, orbital-ballistic mechanics dictate this. To change the initial ballistic path to a reasonably circular orbit the OMS has to be able to direct it's thrust through the center of gravity of the Orbiter or the Orbiter+ET combo... If it can't then the OMS becomes a very powerful Yaw jet that could tumble the Combo much like a fireworks pinwheel. Just like the RCS does with it's off center jets but at 1/6 of a G... Now go back and look at your Shuttle plans and see if the OMS Motors have a Gimbaling system. I did not find one... DEBATE MEDIATOR I was unsure as to Mr. Trowbridge's position so I did some quessing ... again apologies if I am in error ... (Quoting Lawrence Trowbridge to Larry A Hendrickson ) LARRY HENDRICKSON: An empty ET weighs about 66,000 pounds, more than the rated payload capacity of the Shuttle. Therefore, if you intend to carry the ET through the OMS-2 circularization burn, you have to pretty much give up *any* sizable payload for that mission. I do not, LAWRENCE TROWBRIDGE: Larry, excuse the butt-in please, but carrying the ET to LEO is not the same as lifting a payload from the ground. You already have the velocity to reach orbital altitude, so you only have to add enough delta-v to the ET to circularize its orbit. I don't remember how much delta-v that is, but it's only a fraction of what it took to pull it up against gravity and get it up to that velocity. TOM ABBOTT (PRO): Lawrence, the ET reaches about 98 percent of the velocity it needs to reach orbit before it is dumped back into the atmosphere. LAWRENCE TROWBRIDGE (CON): The ET has exactly the same velocity as the Orbiter at MECO. If there is a discrepancy in the velocity needed to reach planned apogee, it must be made up by an OMS-1 burn. This never happened on my watch. The OMS-2 burn is where the velocity is added to circularize the orbit. That one is not much of a kick, if I remember correctly. A similar delta-v to the ET should put it in orbit, then. Since the Orbiter has a typical on-orbit mass of the order of 220,000 lb, and the ET, by Larry's figure, is 66,000, it would only take 1/3 as much fuel to do this as it does to orbit the Orbiter. LAWRENCE TROWBRIDGE: The idea has occurred to me too, but there is one factor that has not been mentioned. THERE ARE NO MINOR MODIFICATIONS to anything connected with the Shuttle! I speak from personal experience. TOM ABBOTT (PRO): True but that gives the impression that the Shuttle is never modified. In fact, if I remember the right number, one of the shuttles, Columbia I think (I'll have to look it up), just recently had something like 804 modifications made to it. LAWRENCE TROWBRIDGE (CON): Yes, Columbia (OV-102) was modified for the Extended Duration Orbiter project. This operation took a year at Palmdale, and was identified as the MAJOR Modification Period. Then OV-104, Atlantis went through same process. This cost billions! I don't remember now, if OV-103, Discovery was put through this process or not, but it resulted in such things as relocating the Modular Auxiliary Data System (MADS) recorder being relocated to where it could not be removed/replaced with the Orbiter in the vertical position. In fact, it could not have been used, as there was no way to make the connections to enable recording, or to dump the recorder after the flight! For $600,000, A cable extension was supplied that enabled the connections to be made. When Dan Germany, the Shuttle project manager, asked what it would cost to leave the recorder where it was, he was told "1.2 million dollars"! I had a similar experience, on a smaller scale with some instrumentation. It took a change of three wire connections to enable 300 strain gages in the wings of Columbia to be used after MECO. The original quote was $125,000 for the change. After two years we got the price down to $70,000, and were complimented for having gotten it so low! For three wires! Thanks for making me think. LARRY: How difficult would it be to give the ET--its' own OMS? It would seem to me a better option would be to separate the ET and dare I use the term robotically build some of the configurations as found in ET-Solutions by Gene Meyers. TOM ABBOTT (PRO): Martin Marietta has designed OMS for the ET that attach to the solid rocket booster thrust points. THOMAS SIMPSON: So how does that work out? We kinda' NEED those SRB hardpoints to hook the SRBs to, in order to get it into (or near, at least) orbit to start with. TOM ABBOTT (PRO): The SRB's are jettisoned 2 minutes after Shuttle liftoff and so the ET's solid rocket booster thrust points are available to attach things to in orbit. THOMAS SIMPSON (CON): Or do we have the crew do an EVA to attach it prior to ET reentry? I'll bet they demand a payraise over THAT one. TOM ABBOTT (PRO): Thomas, if attaching a couple of service modules to the SRB thrust points causes you trepidation, you would really panic if you heard about the dozens of assembly sequences required to assemble the Alpha space station. THOMAS SIMPSON (CON): Perhaps I am missing something, here. As I understand it, the new OMS package we are talking about is intended to move the freshly detached ET to a usable orbit, without (again, presumably; this is the first I have heard of it) the expenditure of a bunch of OMS propellant onboard the Orbiter. As I understand the scenario now, somewhere between MECO and the first OMS burn on the Orbiter, the crew is going to go out and attach the OMS pod to the recently-vacated SRB hardpoints on the ET, all in the very small time window between MECO and the time when the ET would normally reenter. Or do I misunderstand? Are they going to expend a little OMS reaction mass on the Orbiter to lift the ET into at least a minimal orbit and therefore gain a little time to this job properly and safely? I would certainly hope so... TOM ABBOTT (PRO): The External Tank would be put in a minimal orbit before the boost/reboost modules are attached. In the case of NASA's latest External Tank space station design:(Option D/GEODE), an Aft Cargo Carrier (a fifteen foot extension to the bottom of the ET), would carry built-in orbital maneuvering engines and deployable solar panels. The $5 billion External Tank GEODE space station would not require the development of a separate heavy-lift launch vehicle to put it in orbit (as is the case withNASA's $13 billion Option C space station design) but could be launched as a regular shuttle flight. Option D's $5 billion cost is $25 billion cheaper than the $30 billion Alpha (Option A) space station design. ----------- MIKE ZELESKI (CON): 6.5 degrees is still not much compared to the 20+ degree pitch of the SME's and the shift in CG that an attached ET could cause. 60,000 lbs is significant fraction of the Orbiter's mass. TOM ABBOTT (PRO): That may be true, but it doesn't prevent an ET from being used in orbit and it doesn't prevent a Space Shuttle from controlling an ET using its thrusters. MIKE ZELESKI (CON): In fact you state 2 different answers to this question and attribute both one company. This seems very strange to me, that one company would invest in designing two very different engineering solutions to a problem that may not be ever confronted. I am going to inquire into this when I visit Martin-Marietta for a unrelated reason later this month. TOM ABBOTT (PRO):In fact, Martin Marietta has done many studies of the External Tank for various uses in orbit. DEBATE MEDIATOR As for objectivity, while not Gospel and the final word, Tom Abbott is the only poster who has consistently quoted, referred to government and private studies and given addresses to obtain studies done supporting the use of the External Tank as a space station. While those who are "CON" have given some data we have no way to examine the data without being able to obtain the studies or documents they are from. In support of objectivity I implore those who are 'CON" to produce studies refuting Abbott's position ... surely these studies (again NOT gospel) are certainly preferable to opinions, quesses and yes ...feelings. As always ... "...data will out ..." TOM ABBOTT (PRO): According to the "External Tank On-Orbit Inspection Study (1982) done at Marshall Space Flight Center, LARRY HENDRICKSON (NEUTRAL): 1. Do you have a document number? I'd like to drag this one out of the Tech Library and look it over? TOM ABBOTT (PRO): "this study was undertaken at the direction of the External Tank Project Office, Marshall Space Flight Center, NASA, Huntsville, AL. It was authorized by Technical Directive 1.6.2.1-575, "ET Inspection On-Orbit". The Operations Directive directing task accomplishment was Contract No. NASA-30300, Account No. 203780, Supplement No. 100/1.6.2.1, 2 October 1981 (Revisions 575-A, 15 February 1982 and 575R1, May 1982.)" LARRY HENDRICKSON (NEUTRAL): 2. Did the study also address the increased OMS/RCS propellant requirements for carrying 66,000 lb of dead weight through a rendezvous sequence, or only single ET's? TOM ABBOTT (PRO): This particular study was of one ET in orbit. LYNNDEL HUMPHREYS (NEUTRAL): The solid rocket booster thrust points. And where might these points be located? TOM ABBOTT (PRO): The solid rocket booster thrust points are located in the intertank region and near the base of the hydrogen tank. ------------------------------------------------------------------------ JACK SARGEANT (NEUTRAL): Before you hasten to disagree for the sake of debate, think of ways this could be made practical instead. Let's toss this one around a little before we say it can't be done. HUGH GREGORY Agreed! Nice and ON Topic Jack! This should be educational. To start with we will have to modify the tanks so that there is an access hatch at the rear end and the forward end, with an ABSOLUTELY gas and cryo-liquid tight interconnecting hatch between the O2 & H2 tanks. It is easier to do this on the ground, so that your access to the interior is in place before launch. The down side is the weight penalty this will cause will seriously eat into the cargo lift capability of the shuttle. (remember they've been shaving kilo's off of that tank to increase the cargo bay payload as well as enabling a heavier lift to 51.6 inclination orbits). And the 51.6 orbit is THE orbit for any station, other wise you are restricting yourself to just doing Earth observations of the tropical - equatorial regions. You will want to be able to observe the polar areas of the upper atmosphere and at 51.6 degrees inclination you can do this. Food for thought. Contact Cris Fitch for more information about this web site. Copyright © 2001-2003 Cris A. Fitch.