Shuttle fuel tank

Terraformer · 2007-10-19 14:55:54

Does the shuttle fuel tank actually have to be ejected foff the shuttle, or could it be carried into orbit?

Martian Republic · 2007-10-20 06:16:45

Does the shuttle fuel tank actually have to be ejected foff the shuttle, or could it be carried into orbit?

Yes, the space shuttle fuel tank has to be ejected before it reaches orbit. Any attempt to take it into space will virtually eliminate using the cargo bay of the shuttle for caring up supplies to ISS or anything else that you want to take up in the cargo shuttle bay. To take that shuttle tank that last little bit, take a whole more rocket fuel and bring down what you can take up in the rest of the shuttle part of the stack. Then you have another problem when you get those tanks into orbit, what are you going to do with it. We have no way to redeem those tanks once we got them in space, because we have no manufacturing place to work on them or catch any material that might get that might get free when we cut into it. You can't use it to build habitats without sending up other shuttle to bring up resources to encase those tanks with other material so we could use them as habitats. It would be easier to use a Bigelow habitat than redeem a shuttle tank for that purpose. It would not be energy efficient to send those empty tanks to the moon either if we could get them into orbit in the first place. If we just take those tanks into orbit and leave them there until we can use them, they will deteriorate in space and create more space junk that will be orbiting the Earth that will increase the hazard of going into space.

We have already discussed this at great length and these are some of the problems that you run into if you were to try and take those space shuttle tank into orbit. It just not practical to take those tanks all the way into space.

Larry,

publiusr · 2007-11-09 14:44:22

If you burn the mains you can get away with it. I would like to have seen ETs used. Marshall had a plan for an ET station.

Martian Republic · 2007-11-13 20:01:23

If you burn the mains you can get away with it. I would like to have seen ETs used. Marshall had a plan for an ET station.

That wouldn't work either for getting it into space or for using the shuttle tank for a space station. Trying to get that shuttle tank into orbit would take so much more fuel to do that, that you would not be able to use the cargo bay to carry anything into space. There is absolutely no way to use those External Tanks for building a space station in there current condition. You would have to cut holes in them and do other modification to them and then you would have structural problems. You would not have the radiation shielding that you would need once you had them built. Those tanks would deteriorate in space, especially the insulation that on them, which would add to the orbiting pieces of junk in space. So you would still have to overlay those tanks with other things once you had them where you wanted them, which would also be labor intensive and require other space launches to take up the material to use those tanks for that purpose. If you try to make those tanks dual purpose down here before you send them into space so you could use them for a space station, then those tanks would be twice as heavy or heavier and that would make it too heavy to get the shuttle off the ground. So we have a situation where we can't readily take up those tanks, we can't use them once there in space and we can't modify them for a dual purpose before we can get them into space.

If we were going to build a space station, we would be better off buying a few Bigelow space habitats and putting them together.

Larry,

RedStreak · 2007-11-14 11:45:57

Interesting news about new way to store hydrogen:

http://newmars.com/forums/viewtopic.php?p=102776#102776

Check the posted link there.

Austin Stanley · 2007-11-14 16:57:28

As I recall most serious plans involving use this shuttles main tank in orbit also include some other means of adding the extra bit of thrust necessary to get the tank fully into orbit on its own. It really is carried very nearly all the way to orbit with the Shuttle OMS system firing only a minor burn after the ET in jettisoned and the main engines are shut down. The loss in cargo space in the shuttle truly isn't that great (even negligible depending on the orbit the shuttle is shooting for). And could be made up for with a slightly larger or lighter tank, or a small additional booster stage.

I used to be quite skeptical towards the idea of using the ET for anything in space, but the idea does have some merit. As I said before the ET is carried very nearly into orbit, so you wouldn't have to loose that much to get it there. If you COULD use the tank it would provide an incredible amount of additional space. The ET is huge, probably bigger in usable space then the entire ISS.

Additionally the tanks are relatively strong, insulated, and air-tight. Recall that the ET has to support several hundred metric tons of propellant, as well as structurally supporting the orbiter while the SRBs are providing thrust during lift-off. Its certainly as light as they can safely make it, but it is not a particularly flimsy structure by any means. While it may lack a dedicated micro-meteorite shield and radiation shielding its not clear that such things are absolutely necessary or that they could not be retrofitted fairly cheaply into the station. Certainly its relatively hardy construction should provide some protection.

Recall as well that Skylab was essentially an upper stage for the Saturn V rocket modified into a space-station. So I believe, in theory, that not only the idea could work, but could work very well.

Alas, in practice I believe there are some significant difficulties.

#1. Spent fuel. Actually this isn't a problem, but I though I'd point out that it isn't anyways. LOX and LH2 (especially) will quickly dry up and evaporate away if exposed to vacuum, which should be easy to do in space. Just leave the lines from the SSME open. Their might be slight possibility of explosion, but that seems unlikely to me. LOX and LH2 aren't hypergolic so their fumes are unlikely to spontaneously ignite.

#2. Access. While there ARE access hatches in the LOX and LH2 tanks they are relatively small and not suitable for use in space (I think they get welded shut as well). In order to gain access to the LOX and LH2 in space they would have to be re-engineered for bigger access ways. Its not clear to me to what extent this is possible/practical.

#3. Assembly. The biggie. Assembly in space has proven to be difficult and time consuming. This is doubly true if EVA is required (which seems likely). Loiter time is limited in space (for the shuttle at least) so this labor and time is doubly expensive. I can think of no cleaver means of reducing this obsticle.

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In any case while I don't think we are likely to see the ET used in any fashion in the immediate future, I think the idea DOES have some merit. At least enough that it should be at least examined, not rejected out of hand.

Terraformer · 2007-11-16 07:54:24

Fit engines to, it and turn it into a massive cargo craft that could move through different orbits collecting space junk?

SpaceNut · 2007-11-16 08:16:56

One of the first groups that wanted to use the shuttle ET's was Space Island Group

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#1 2007-10-19 14:55:54

Re: Shuttle fuel tank

#2 2007-10-20 06:16:45

Re: Shuttle fuel tank

#3 2007-11-09 14:44:22

Re: Shuttle fuel tank

#4 2007-11-13 20:01:23

Re: Shuttle fuel tank

#5 2007-11-14 11:45:57

Re: Shuttle fuel tank

#6 2007-11-14 16:57:28

Re: Shuttle fuel tank

#7 2007-11-16 07:54:24

Re: Shuttle fuel tank

#8 2007-11-16 08:16:56

Re: Shuttle fuel tank

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