The original Skylab was a space station based on the middle stage of a Saturn V moon rocket: the fuel and oxygen tanks removed and electronics and living space installed. It of course burned up in re-entry decades ago.
Has any serious thought gone into salvaging an external fuel tank from a shuttle launch and making a space station out of that?
The Shuttle’s external tank is dropped at only 111 km, which is a bit above where SpaceShipOne managed to reach and no where near “true” orbit; Skylab orbited at ~300km and the ISS orbits at 350km.
I have a vague recollection that this idea was proposed early in the history of the shuttle. Obviously nothing came of it.
But boy that’s gonna be hard to google…
Er, Skylab was more like 400…
But this retrofitting was done on the ground. The Skylab is actually based on the third stage of the Saturn V; the first two stages could lift it into orbit, without using fuel or engines on the third stage.
The Shuttle needs the fuel from the External Tank to get to orbit. It would need to act as a fuel tank and a space station. This would either involve extensive redesign of the tank, or extensive work in orbit, or both. The External Tank is a vital component of a manned rocket, so even minor design changes would have to go through an extensive and expensive certification process. Launching several small space station modules is cheaper and safer.
It can’t have burned up entirely. I was at school at the time, but I recall debris from Skylab being collected in Western Australia. Or was there more than one Skylab?
Not entirely, but almost. The largest piece recovered as an O2 tank, about 2ft long as I recall. (It’s on display at the US Space and Rocket Center here at Huntsville, AL).
Back in 2002 Buzz Aldrin et. al. proposed using the external fuel tanks as the basis for “cycler” spacecraft which would be put into an orbit which would continual cycle between Earth and Mars.
http://spaceflightnow.com/news/n0202/07marshotels/
Keep in mind that was pre-Columbia and pre-Shuttle getting put on the sh*tcan list.
Skylab was actually designed as a web workshop; that is, it would be part of the propulsion system with all of the hardware–decking, basic plumbing, attach points–built in, then using it as tankage for fuel and oxidizer. After it was on station, the crew would board and assemble all of the sensitive gear and stock perishable goods. After the Lunar Program was cancelled and Apollo Applications got scaled back to just Skylab, there were surplus Saturn V vehicles and it was put on station on its lonesome, but the lab was originally designed to be launched wet.
The Shuttle is essentially done thrusting (except for orbit stabilization burns) when it drops the main tank, so there’s little reason that it couldn’t be brought along for the ride, and in fact during the concept phase there was some concern with using an external tank insofar as it might follow the Shuttle up and contact it, thus requiring a auxiliary propulsion system to make sure it re-entered. As it turned out, none was needed; the tank is blown free with a fairly simple ordnance separation system and aeroloads (along with venting the 0[sub]2[/sub] tank to give it a deliberate tumble, assuring breakup) pull it away from the Shuttle. Although MECO (main engine cut-off) is at somewhere on close order of an altitude of 100 nautical miles, the External Tank will continue upward on a ballistic track and then tumble down into the Indian Ocean.
As for structure, because the O[sub]2[/sub] reservoir sits at the top of the ET (for mass property reasons, resulting in a lot of trouble for the rest of the design) the whole structure is somewhat overdesigned versus having the H[sub]2[/sub] tank on top or the tanks sitting side by side. So there’s almost certainly enough structure to maintain pressure. It would, as scr4 notes, require extensive redesign to accomodate the docking/entry system, decking, plumbing, and connection points necessary for fitting it out as a habitat, but the majority of that is the quality assurance and safety procedures and paperwork the risk-adverse NASA requires. If the Russians were doing this, it would be quick work, toravich. (Hey, it might leak a bit, but you send up a couple of tubes of caulking and it’s all good. Don’t knock it; the Russians have locked a hell of a lot more man-hours in “permanent” space habitats than we have, and did so while NASA was grounded and watching Skylab surf the atmosphere.) As for the reduciton in volume, while I can’t find the numbers at hand, I recall the lost tankage in Saturn IVB was somewhere around 2%. (The additional weight is somewhat more bothersome, but adapting from the lightweight ET and/or going up with less than full payload can probably make up for that.)
I think it could be easily doable from a techical standpoint. However, there’s a big question of why you would do such a thing. After all, we’ve spent tens of billions on the ISS, so why would we float a new habitat? What are you going to do with it, and how long do you intend it to be utilized? For short missions, we have the Spacehab module; longer “science” missions go to the ISS.
Skylab was, at least in concept stage, a reaction by NASA not wanting to let the Air Force have all the fun with the Manned Orbiting Laboratory. When the MOL was cancelled (and with it Air Force interest in a manned space transit capability), Skylab became backburnered until the Lunar Program was on the block and NASA needed to find new missions to justify Apollo and Saturn V production. The continued existance and purpose of the STS is mostly predicated on Space Station Alpha/Freedom Station/International Space Station, especially when it became clear it was fiscially nonviable as a reliable commercial-grade heavy lift vehicle. Introducing a new habitat begs the question fo what the ISS (and by extension, the STS) is doing at all.
Not a bad idea for cheap habitat space, and certainly not technically infeasible. It just begs the question that nobody wants to ask in the first place.
Stranger
As an aside, I’m surprised that there hasn’t been another major episode of falling space junk since Skylab.
Thanks for pointing that out; I knew the skylab was conceived as such but didn’t realize there was so much work done along those lines.
The Shuttle is a manned spacecraft, so they’d better be risk-averse! IIRC the skylab was launched unmanned. Even today it would be much easier to do something like that with an unmanned launcher than the Shuttle.
Thes days they (all space agencies) are more careful about what happens to old hardware. When space stations and large satellites are near the end of its life, they are deliberately de-orbited above the ocean. Unfortunately, sometimes it means destroying a functional satellite, e.g. when one gyroscope has failed, and one more failure would make the satellite uncontrollable.
Well, Skylab was originally intended to be launched as part of a manned flight (actually piggybacked onto a lunar orbit or proposed solar telescope mission, later as part of a dedicated Skylab manned flight) but because in-process Saturn Vs were available due to the cancellation of Apollo XIIX-XX, there was a spare Saturn V booster, permitting Skylab to be launched “dry”, i.e. fully outfitted. (Had their not been, it probably would have been launched on a Saturn IB in the “wet” configuration and fitted out by later by the first crew.) Still, you are correct in saying that NASA would have to be much more careful in the post-Challenger/Columbia era than it would during the freewheeling Apollo period. Honestly, a five section booster and a small liquid upper stage, similar to the Ares I booster being used for Orion would probably be a better choice on a cost basis than trying to modify an ET for use in man-rated flight.
One of the early STS missions was actually intended to be a rescue mission for Skylab in the 1979 timeframe. Unfortunately, Shuttle deployment slipped (problems with the thermal tiles) and the Shuttle didn’t reach orbit until 1981. These days, the procedure is to intentionally deorbit and try to control entry and impact, though that’s hardly a precise science (witness the deorbit of Mir).
Stranger