From the website http://clubs.yahoo.com/clubs/towards2001andbeyond Copyright © 1994-1999 Yahoo! Inc. All rights reserved. Clubs Help. Privacy Policy. Terms of Service. Legal Disclaimers. ======== Message 140 - Re: Agreed J_D_Ray (31/M/Portland, OR) Mar 14 1999 3:21AM EST Agreed. We need some sort of LEO station before we can get too excited about putting something on the moon or Mars. I think that a (relatively) small station made out of a cluster of Space Shuttle External Tanks (SSETs) would make a fine station. We don't need to start with one of the big wheel stations or Bernal Spheres that everyone thinks about when they think "space station." Check out www.sns-access.com/~jdray/station for a couple of ideas on station design using SSETs. So what sort of facilities do you think we would need on such a station? Hotel services for sure. Some sort of refuelling station. Shipping and receiving. How about a fab of some sort? If this station was designed with the idea of Lunar station support in mind, then I'd think facilities with Lunar gravity would be good, with some full-g facilities as well, letting residents move back and forth between the environments so they could get "acclimatized." Thoughts? J.D. ======== Message 142 of 161 - Re: Shuttle Tanks DerStoat (36/M/Seattle) Mar 14 1999 9:08PM EST I don't think we are going to make most of the structure of a station out of discarded shuttle tanks. They just were not designed as station compartments. You would still need to bring complete units to fit inside them. The savings of the skin would be quickly lost in the cost of construction in space, which is much more complicated then assemblely on the ground. Personally most of the ideas for stations made from the tanks look a little like trailer parks. The only thing I can think of the tanks being used for might be warehouses and final assemblely sites. As a final assemblely site you could replace one end with a large air tight door. This would allow those doing the work to ware much lighter suits since it is partly sheilded from radiation and could have a partial presure. This would make much of the final assemble much simpler. Stoat. ======== Message 143 Re: How, then? J_D_Ray (31/M/Portland, OR) Mar 15 1999 4:27PM EST >You would still need to bring complete units to fit inside them. Yes, but there would be a significant structural savings in the design of the insert if you didn't have to build a pressure shell. If they can hold the pressure of a load of LOX and LH in Earth gravity, then they ought to be able to act as a pressure shell for an atmosphere. > The savings of the skin would be quickly lost in the cost of construction in space, which is much more complicated then assemblely on the ground. If it's true that NASA would actually incur a cost savings to carry the ET all the way to LEO, then they should pay someone to collect them in LEO. The tank should at least come to the consumer for free. So where's the cost of getting it there? Sure, you have to consider the cost of collection and retrofitting, but I still think it would balance to the positive for the people doing it. > Personally most of the ideas for stations made from the tanks look a > little like trailer parks. Well, I'd have to agree with you there. But I don't think we should be worrying too much about style at this point, just having a place to work. Having a shirtsleeve area to work would be a great bonus. That also reduces the amount of training you have to put your tradesmen through; they don't have to figure out how to use a heliarc machine while wearing a hard suit. So, what's your proposal for putting up an initial station? Build the whole thing in sections and launch it up like the ISS is? How would you design the station? Gravity? How much? How big would you make it? What services would it offer? However we get the thing up there, it has to be done. We need designs to compare and contrast. J.D. ======== Message 144 Re: About the Shuttle tanks... crimw (23/M/Kirkland, WA) Mar 15 1999 6:59PM EST The tanks are actually two tanks. One for the LOX and one for the Hydrogen. The nice brick red shell is just that, a shell. It covers the tanks inside. The shell would not be able to be preasurized, because it was never meant to be.(Or strong enough to be) The two internal tanks might be able to be used, but even then, you have just cut your "massive" working area by half. Besides, once the Space plane and Roton get active, you will have $1000 per pound transport costs. That means most things will be better made on earth and launched. ======== Message 145 Re: Tanks DerStoat (36/M/Seattle) Mar 16 1999 1:54AM EST The tanks would provide only a tiny part of what the hull of a space station needs. You need radiation sheilding to reduce the hard radiation of space. This is one of the reasons spacewalks are so limited going out of the hulls sheilding is unhealthy. The hull also needs insulation so the occupants are not frying half the time and freezing the rest. Then there is all the wiring, ventelation, hatches, etc. In effect 90% of the craft would need to be flown to the tank. Then you would have to go through the expensive and dangerous zero-G construction. Cutting and welding are no cake walk on earth. They would be nightmarish in space where hammering is difficult. My comment about the ideas looking like trailer parks had little to do with the estetics. What I meant was they made me think of the collection of poorly constructed flimsy units that are often a hazard to their occupants. As for what I think should be part of the first commercial station I have already put for ward some in previous posts. I have had an idea of what the first product brought from space should be. NASA has been had the wrong direction on the ecconomic possibilities of space. They have been looking for industrial products that could be made in space. But that is not what was brought back by the European explorers. They brought spices, silk, furs and other exotic luxuries. That is the first things that should be manufactured in space. I'm not saying that I do not think space will offer opportunities and benefits for the common man but we need to pry the cash from the weathy first. I wonder if crystals formed in zero-G would sell well. What else could be sold for thousands that requires an environment that is in earth orbit. What would the wood of a tree grown in zero-G look like. Anyone else have other ideas. Stoat ======== Message 146 Re: External Tanks gage7369 (M/Columbus, OH) Mar 16 1999 12:09PM EST There is a book called ET Solutions. It outlines all the uses and capabilities of the external tank as a STARTING point. Not a permanent station. The radiation problems are of limited concern, due to the Van Allen belts of the Earth. Example: Indeed, how thick is the shuttle's skin? The ET's are also not completely drained of fuel when the shuttle separates from them. With a small retrofitted propulsion system the tanks could place themselves into a stable orbit. If it doesn't, there is no loss because it was meant to burn up anyway. With over 80 shuttle flights having been flown in the life time of the craft, if only half of the ET's were saved, we could have quite a sizable space station. Whether or not it looks like a trailer park is of no concern, form follows function. It is an inexpensive foundation from which to have a station. And from what is gained in experience from zero-g structuring and architecture, surely the same principals would be used, so that ET's could be used to build a presence on the moon. ======== Message 147 Re: Flimsy? H2 tanks capable of launch acceleration? lasswell77 Mar 17 1999 4:48PM EST >What I meant was they made me think of the collection of poorly constructed flimsy units that are often a hazard to their occupants. I think that the inside of the Hydrogen portion of the Shuttle external could probably stand up to a Hollywood style gun fight. (using pistols, not long arms) In order to endure multiple G stress with a huge load of liquid Hydrogen, those shuttle tanks have got to be build with greater structural integrity than the engine block in your car. The insulation value of tanks holding a huge load of liquid at three degree kelvin is not to be discounted, either. Flimsy, this ain't! The internal structures used in any proposed facility might run towards "pipe and drape", fabric and tubing structures. These will provide something to stand on and something to direct ventilation. Whatever is used, it will likely be light, simple to build, and easy to repair. That might be flimsy. The reason that shuttle tanks evoke interest in me is not that they are a long term solution, but because they are "low hanging fruit". They may not be a mansion, but they will likely keep you out of a rain of cosmic particles better than any suit you can wear. Patrick ======== Message 148 Re: Construction DerStoat (36/M/Seattle) Mar 17 1999 11:53PM EST The ET will not be used for one simple reason, it costs too much. Have you ever seen how off shore drilling platforms are built? They are constructed in section on land and final assmeblely is done on site, just like space stations. Do you know why? Because the cost of construction in a hostel environment is amazingly high. Most log cabins were made from purcased per cut logs for the same reason. You make it sound like all will be needed is a fan and a few chairs. In reality it would reqire a complete engine and navigation system to keep from plunging into the atmosphere. A power system would be required. The power system on Mir proved to be volitile, jury rigging one is not a good idea or you could incinerate your crew. Communication would be needed, another system that needs to be perfect, failure of that can leave you dead in the water. It will require extensive wiring internally and most likely externally. There may be a day when the remaining ETs are salvaged for some purpose. That will only come after we have stable private platforms. As is always salvage will not be fantastically profital but there will be a market for it. Stoat ======== Message 150 Re: Prefabricated is prefabricated. lasswell77 Mar 18 1999 1:10PM EST Have you ever seen how off shore drilling platforms are built? Yes, I have been to the Gulf, and I've seen drilling platforms being built. Where I live, they have a supertanker class drydock that on one occasion they used to berth a barge, then the drove a 200 ton rated crane down a ramp to the floor of the drydock. This was done to transfer prefabricated houses to the barge. The houses were then offloaded in Alaska for use in a rapidly building naval base. I see no real reason why internal partitions, engines, navigation systems, electrical systems, ventillation systems, waste disposal systems, communications systems, industrial systems, access hatches, air-tank refilling stations, damage control kits, noise reduction units, and anything else that needs to be installed cannot be prefabricated on earth and locked into place in space. Even at "only" a thousand dollars a pound, I think it will be some time before "space squatters" will migrate into the heavens and start building cardboard shacks in low rent orbits. (You might be a space redneck if you airlock depressurizes and kills more than three dogs.) Patrick ======== Message 151 Re: ...and furthermore... J_D_Ray (31/M/Portland, OR) Mar 18 1999 5:19PM EST ... and when it comes to simple things like sinks, chairs, girders, hatches, nuts, bolts, washers, and other things non-mechanical in nature, the best thing to do is manufacture components on the moon and send them down to LEO, GEO, or wherever your budding station is. Mark Prado of PERMANENT writes: "It takes more than 10 times more energy, theoretically, to get into geosynchrous Earth orbit from the surface of the Earth than from the surface of the Moon (that is, a circular orbit). The energy required from asteriods near Earth could be less or more than from the Moon, depending on the particular asteroid's orbital properties. Adding in the heavy vehicle and complexity associated with Earth launch, and launching the fuel for later in the flight, getting materials off of the Moon and especially from asteroids is much easier than from Earth. " See the full text at http://www.permanent.com/t_theory.htm#Earth_Moon_energy As far as insolation and radiation go, most designs that I've seen for using ETs for stations call for covering the outside of the station with a one-meter shell of regolith to absorb the energy particles. It would also work right smartly as an insulator. For power, just because the Russians had a bad experience with their power supply doesn't mean that everyone else will. There are many proven designs for solar panel power supply, a few nuclear, and even fuel cells for power storage. I think something could be figured out. By the way, solar cells are simple enough that they can be manufactured on the moon as well. Consider that the ISS, when complete, "will have a mass of about 900,000 pounds." [Boeing web site] At $1,000 per pound, that's $900,000,000 just to put the thing into orbit, let alone pay to build the thing. I realize that "less than a billion dollars" to launch a space station may be a good number, but I think there are cheaper ways. Like building some of it in orbit. J.D. ======== Message 152 Re: COST DerStoat (36/M/Seattle) Mar 19 1999 12:23AM EST The theory you work on is the use of the tanks will save money. You are wrong. First the only savings is costs involving the hull of the station. In this case you do not even saved all of the costs since the tank was not designed to be the hull of a station. Therefore you will need to do some of the fabrication in orbit. It is a fact that any job will take much longer in a hostel environment then it dose in a controlled environment. This means that even if the costs of the time is identical you will have blown any savings on fabrication. But the cost of the time is not identical, a trained astronaut is expensive, much more expensive then a construction worker. Any tool needed for the fabrication will cost 10K a pound to get there. The tools are also more expensive since they need to be specially design to work in the environment. You may spend enough to build a station just to prepare the tank to be used. You also assume you have saved the cost of putting them in orbit. Again you have not. The tanks were not set in stable orbits and are right now most likely in uncontrolled tummbles. They will need to be brought to a proper orbit. There are two ways to do this. One you could go to it with an engine, fuel(any remaining fuel will have long ago out gassed), and navigation system. This will most likely weigh as much as the tank itself so you have just blown the cost of bringing it in to orbit. Two you could tow it into position. The only difference here is that in this method you don't get to leave behind anything that might be used in the future. Now to the putting everything together. Saying a prefabricated hatch is the same as a prefabricated station is like saying a prefabricated doorframe is the same as a prefabricated house. Sounds pretty foolish to me. The time it takes to assemble anything in a hostel environment is always much more than the time it takes to assemble the same thing in a controlled environment. Again the time of the people doing the assemblely is more expensive. Again the tools to do the assemblely are more expensive. I know the idea of living in a gas can facinates some people but I am not interested in paying MUCH MORE for a LESS FUCTIONAL station. Stoat ======== Message 153 Re: Huh DerStoat (36/M/Seattle) Mar 19 1999 1:05AM EST By the time we have developed an industry on the moon that can produce even the simplest of hardware what makes you think there will be any ETs. The only reason the tanks were used was to cut design costs. To get the equipment to the moon to set up an industry we will need much more effecient launch vehicles. So either you will need to still lift the entire mass from the earths surface or something else will have to be used for the hull because the ETs won't be there. Anyway since when is a hatch a non-mechanical item, what do you think it is a plywood door. Stoat ======== Message 154 Re: A few words lasswell77 Mar 19 1999 2:28PM EST First from Webster: Main Entry: hos·tile Pronunciation: 'häs-t&l, -"tIl Function: adjective Etymology: Middle French or Latin; Middle French, from Latin hostilis, from hostis Date: 1580 1 a : of or relating to an enemy b : marked by malevolence c : openly opposed or resisting d : not hospitable (Thanks to http://www.m-w.com/dictionary.htm ) According to the NASA site the external tank masses about 30,000 kilos. Based on your pricing of $22K per kilo, that makes each tank in orbit a pricey $660 million. Using comercial space ventures to lift the same mass, it is only about $66 million. Either way, it is a valuable object that is being dumped into the Indian Ocean every time we launch the shuttle. None of the External Tanks are in orbit. About prefabricated hatches and other prefabricated structures for use on a ET based station: it can be done. To use your drilling platform analogy, when the valve on the top of a well blows, there are prefabricated replacement valves that can be used to replace the broken one. Capping a well has got to be more hostile an activity than working in space, at least according to the casualty figures. In fact, similar technologies can be used to obtain the same results. Pressure control on an otherwise unprepared object is the goal in both instances. The hydrogen tank is 331 inches in diameter and 1,160 inches long. There are internal structures to prevent the hydrogen from generating vortex (think about the a olympic sized pool with a 17 inch drain and the whirlpool that would cause, dramatic effect on flight performance). This is roughly equivalent to a 5,350 square foot industrial space. I don't know how much square footage rents out for where you live, but in orbit it's pricey. Since we know that the assembly will be difficult before anything is designed, there are a lot of shortcuts that can be taken on the ground to improve assembly ergonomics. I imagine a lot of adhesive backed hook and pile closure material (AKA Velcro (TM) but 3M makes better versions) to be used. In fact the interior use coveralls may look like the famous Velcro (TM) suit that David Letterman had made. Not the spandex and fishbowl helmets previewed by the pulp magazines, but functional. ======== Message 155 Re: Hmm.... J_D_Ray (31/M/Portland, OR) Mar 19 1999 4:38PM EST Really, John, I don't think either of us has all the answers. I think I've done due dilligence on referencing material to support my arguments. You, on the other hand, seem to be content with telling us what you think. For the most part, that's okay with me, but please refrain from being so blatant as to tell me that I'm wrong because I disagree with you. There's an excellent resource on the web that compiles the makeup of the ET. You can find it at: http://www.ksc.nasa.gov/shuttle/technology/sts-newsref/et.html I would ask that you at least read this so that we can continue this discussion with the same data in mind. Most designs for space habitats use only the Main External Tank (the hydrogen portion) and discount the usability of the oxygen tank. From that web site, "The liquid hydrogen tank is an aluminum semimonocoque structure of fusion-welded barrel sections, five major ring frames, and forward and aft ellipsoidal domes. Its operating pressure range is 32 to 34 psia. The tank contains an anti-vortex baffle and siphon outlet to transmit the liquid hydrogen from the tank through a 17-inch line to the left aft umbilical. The liquid hydrogen feed line flow rate is 465 pounds per second with the SSMEs at 104 percent or a maximum flow of 47,365 gallons per minute. At the forward end of the liquid hydrogen tank is the ET / orbiter forward attachment pod strut, and at its aft end are the two ET / orbiter aft attachment ball fittings as well as the aft SRB-ET stabilizing strut attachments. The liquid hydrogen tank is 331 inches in diameter, 1,160 inches long, and has a volume of 53,518 cubic feet and a dry weight of 29,000 pounds." Five major ring frames seem like great places to attach joist structures to me. Add a honeycomb aluminum subfloor and skin it with whatever sort of flooring material you want, and you've got somewhere to stand. With an operating pressure of 32 to 34 psia (pounds per square inch of atmosphere), there's plenty of buffer to support containment of a 15 psia atmosphere like we have here on Earth [Ref. Marine Engineer's Handbook]. The tank is about 27 feet in diameter (8.3 meters) and 97 feet long (29.4 meters). That's enough volume to contain a nine story building with 2.5 meter ceilings. 29,000 pounds of aluminum and steel is a lot of material to throw away. Complex tools will naturally have to be launched up from Earth. I'm assuming that your quote of "10K per pound" is an unintentional typo, as you referred earlier to $1,000 per pound for launch of material in the Roton vehicle and we determined earlier that the Space Shuttle's price is around $5,000 per pound. Comparing the mass of a carpenter's toolbox to the mass of the house he's building is an improper comparison, as far as I can tell. On the subject of orbiting the ET, what makes you think that NASA isn't capable of inserting an ET into some sort of stable orbit where it would await use? There's no reason that the ET can't stay attached to the orbiter until it's in orbit. Stationkeeping engines (carried up in the Shuttle) could be attached, the extra fuel recovered (converted to water) and the tank pressurized with an atmosphere before the orbiter detached from it. From there it would be a small effort (relatively) to outfit the interior wit basic decking. I don't think anyone was comparing a pre-fabricated hatch to a pre-fab station. My statement was that, with a -simple- fabrication factory on the moon, simple, non-mechanical or simple-mechanics parts (such as doors with hinges) could be manufactured and launched down to LEO for less energy cost, assuming that the factory was in production mode, than launching things up from Earth. There are plausible designs for making moon bases out of ETs as well. Lastly, working on the bottom of the ocean is more or less as hostile as working in space, and we commonly construct things in that environment. I'm going to quit for now. Thanks for your time. J.D. ======== Message 157 Re: Page full of abstracts J_D_Ray (31/M/Portland, OR) Mar 19 1999 8:52PM EST Find a page full of ET-related abstracts here: http://www.triptyk.com/crisf/text/et_abstr.htm ======== Message 158 Re: ET launch cost phobos1998 (17/M/Evesham, UK) Mar 22 1999 6:08AM EST Since the ET is generally dumped, we can consider the cost to get it into orbit as being the amount of extra fuel that the Shutle would need to carry it the rest of the way. The usual statistic of how many thousand dollars per kilo is for cargo. It's so high because the cargo has to pay for the launch costs, including the ET. ======== Message 159 Re: Actually a savings... J_D_Ray (31/M/Portland, OR) Mar 22 1999 11:56AM EST From the PERMANENT web site: "Notably, if the tank is saved, the Space Shuttle can lift MORE payload up from Earth, or it can go up to a higher orbit. Why? Saving the tank would eliminate a manuvering operation required to send the tank to burn up safely in a small target area at a remote spot in the Indian Ocean. This requires use of fuel on board the Shuttle, which is a compact but relatively heavy fuel (hydrazine), which is also used to propel the Shuttle to its final orbital velocity. Saving the tank would also allow more of the tank's leftover fuel to be used (by a slow burn at lower tank pressure). An engineering study by the tank's manufacturer, Martin Marietta, shows that the Shuttle can take an extra ton of cargo to orbit if the tank is saved." ======== Copyright © 1994-1999 Yahoo! Inc. All rights reserved. Clubs Help. Privacy Policy. Terms of Service. Legal Disclaimers.