NanoRacks Plans To Turn Used Rocket Fuel Tanks Into Space Habitats (ieee.org)

An anonymous reader writes from a report via IEEE Spectrum: A couple of weeks ago NASA announced it has committed $65 million to six companies over the course of two years for the purpose of developing and testing deep-space habitats that could be used for future missions to Mars. One of the six companies, called NanoRacks, is attempting to take empty fuel tanks from the upper stages of rockets and turn them into space habitats on-orbit. IEEE Spectrum reports: "A rocket like the the Atlas V, which can deliver payloads of nearly 19,000 kg to low Earth orbit, consists of three primary pieces: on the bottom, you've got the first stage booster, which consists of a huge engine and some big tanks holding kerosene fuel and oxidizer. Above that, there's the second stage, which consists of one or two smaller engines, a big tank for storing liquid hydrogen fuel, and a smaller tank for oxidizer. The payload, which is what all of the fuss is about, sits on top. The first stage launches the rocket off of the pad and continues firing for about four minutes. Meanwhile, the second stage fires up its own engine (or engines) to boost the payload the rest of the way into orbit. On the Atlas V, the second stage is called Centaur. Once Centaur gets its payload where it needs to go, it separates, and then suicides down into Earth's atmosphere. Getting a payload into space is so expensive because you have to build up this huge and complicated rocket, with engines and guidance systems and fuel tanks and stuff, and then you basically use it for like 15 minutes and throw it all away. But what about the second stage? You've got a whole bunch of hardware that made it to orbit, and when getting stuff to orbit costs something like $2,500 per kilogram, you then tell it to go it burn itself up in the atmosphere, because otherwise it's just useless space junk." NanoRacks thinks this is wasteful, so they want to turn these tanks into deep space habitats. IEEE notes that the hydrogen fuel tank on a Centaur upper stage has a diameter of over 4 meters, and an interior volume of 54 cubic meters, while the inflatable BEAM module that arrived at the ISS earlier this year has an interior volume of 16 cubic meters. For more details, IEEE Spectrum spoke with Jeff Manber, CEO of NanoRacks, and Mike Johnson, NanoRacks' Chief Designer. You can read their responses here.

Comments

I don't get it

[telchine]

I don't understand how this can possibly be cost effective. Can anyone explain?

Re:I don't get it

[johannesg]

So an empty metal container made for storing fuel is also a great place to live? It has precisely the right properties in terms of structural integrity, heat and radiation shielding, etc.? Putting all the required machinery to sustain life inside is cost-free?

Or, if it is none of those things, changing all that stuff in orbit is actually cheaper and easier than launching a complete habitat from earth?

(hint: the answer to all these questions is "no")

Re:I don't get it

[meerling]

Yeah, it's not exactly new, but even so, nobody has bothered to try and actually do it yet.

Re:I don't get it

[Rei]

And the US did launch a converted stage in the 70s with Skylab (albeit, Skylab was built on Earth and didn't contribute propellant / thrust... a rather different beast ;) ). That is, a dry workshop rather than a wet one.

To a rocket scientist, it's "obvious"; to a habitat designer, it's a nightmare. They're designed for dramatically different needs, and in-space construction is very difficult (and thus expensive). Orbital habitats are not just big shells, they're complex structures that take a lot of work to make. The original proponent of the wet workshop concept, George Mueller (who had worked with Von Braun on the idea), himself had switched to arguing for a dry workshop over a wet one by 1969 (this eventually became Skylab), telling congress that the wet concept had become just an inferior stopgap based on necessity rather that desirability.

There's this concept that launch costs are everything. They're not. A lot of times, it really is just cheaper to spend more in launch costs than to do more engineering, assembly, and/or in-orbit work.

Re:I don't get it

[rtb61]

Building big stuff in space doesn't make all that much sense yet. Building big on the Moon, makes a lot more sense and a lot of the raw materials are already there. Just need a binder and some earth moving equipment, nuclear powered earth moving equipment, the binder, well those tanks can be reused. The moon has a couple of big advantages, much lower gravity and no atmosphere to deal with, definitely a better place to build the components of a space station. The smart research is in how to use the raw materials available on the moon to best fabricate high mass and large components, to be used elsewhere in space and of course to rapidly expand the size of the moon base to properly develop recycling life support systems for hugely extended even permanent stays. You certainly would not want to return fuel tanks from the moon but you would not use them for habitats either, that has to be engineered from moon dust.

Re:I don't get it

[rgbatduke]

The article intro above actually explains this, if you read it. The fuel in this tank is BURNED, getting the payload into orbit. In the Apollo mission days, the payload was e.g. a third stage that went to the moon and back, as these are BIG rockets. In the past, the second stage tanks would be "thrown away" and allowed to reenter and burn up, but that's slightly insane given the roughly 32 MJ/kg direct energy cost (multiplied by a few orders of magnitude) of lifting anything at all into orbit.

The reasoning is then as follows: We've gotten this great big cylindrical chunk of pressure-tested metal -- remember, it held liquid hydrogen at HIGH pressure securely through a launch exerting many g's of acceleration -- into orbit. It already cost us millions of dollars to build, and tens of millions to get it into orbit as a SIDE EFFECT of lifting this other, really big payload. Let's not waste it!

So, what can we do with it? Well, given that it is roughly the size and even the shape of a good sized mobile home or the living volume of early submarines, making it into pressurized living space is an obvious choice. It is pressure tested at many times the 0.5-1.0 atm pressure differential needed to sustain human life in space. It is made of high quality, carefully x-rayed, stress-tested metal (because NASA would be insane to fire a rocket into space with humans on board with anything less holding in the fuel of the rocket). The metal has been carefully crafted and annealed to be able to handle liquid hydrogen temperatures without becoming brittle, so it is also proofed against your concerns with heat -- humans cannot tolerate any temperatures this metal is unlikely to be perfectly capable of withstanding, and besides, shielding it from sunlight is a matter of wrapping it in a reflective mylar blanket that weighs almost nothing and can easily be shipped up as part of the conversion kit.

As for radiation shielding -- that I don't know about, but I very much doubt that it is an issue. If the Earth gets hit dead on with a solar flare, I don't think there is anything we could reasonably put humans inside in orbit that would be "safe". It's not clear that being on the Earth's surface inside the atmosphere would be "safe". If the metal that the container was made of wasn't adequate as shielding during such an event -- I'm pretty sure it would be perfectly good most of the time -- and we had something better (but smaller and more expensive) then humans could retreat into the latter as a "shelter" to wait out the storm.

Life support machinery and furniture for the interior of the tank turned into habitat is a small fraction of the weight of the whole thing, and weight into orbit costs like gold.

Now let's compare costs. Suppose you used the Atlas to launch an Earth-built space habitat directly into space as to you suggest, and just wasted the second stage tank as usual. It costs you one launch to get the habitat into space, and the interior volume is almost certainly going to be smaller than the second stage tank volume. Now suppose that you take the empty tank and just hook it onto the habitat you just launched (which already has all of the life support machinery, radiation tolerance etc that you are worried about. Voila! You've more than doubled your available habitat volume in space at (almost) zero additional marginal cost! EVEN if it isn't AS safe as the primary habitat in the event of a solar storm, well, astronauts can always retreat into the primary habitat during such a storm and still use the tank as room for experiments, hydroponics, their ping pong table, room to spread out in to avoid going nuts.

The last question is: What do you have to do to the tank to FACILITATE this so that it isn't being done on an ad hoc basis? As you say, certain pieces of work are way cheaper on Earth than they will be in orbit. Should we build the tank out of slightly different metals so it IS a better radiation shield? Should we pre-install ductwork for ventilation and wiring and liquid

Re:I don't get it

[Rei]

What you need is: Oxygen, Radiation shielding, Water, Food, Power and some gear.

Yes, it's totally that simple! The ISS has hundreds of thousands of parts, but only because congress insisted on adding thousands of Machines That Go Ping for no good reason. And random objects totally love being submerged in liquid oxygen and liquid hydrogen. And empty tanks are totally easy to haul all the way to orbit when pre-loaded with fittings and jackets and extra tanks. And building things in space (including bloody *welding*) is such a nothing job that totally costs nothing!

Meanwhile, in the real world...

The tanks will serve as basic habitats etc., you could grow food (wasn't this successfull?) in one of them to replenish your oxygen supply.

((Snicker))

Everything which does not need to be inside, you leave it outside,

((Snicker))

Re:I don't get it

[LordHighExecutioner]

Very easy: just apply the concepts that were behind the new economy boom in 2001 to today's space travel industry. Now sit down and wait for the crash...

Re:I don't get it

[MachineShedFred]

It's the concept of the wet workshop that goes back to the Apollo days. The thought was that if funding continued, they could either retrofit the tanks of a spent S-II stage after you already spent the energy to get it into orbit into a workshop / living area, and then push it deeper into space to use; or you have the equipment already mounted in there and sealed up, and when you reach orbit you vent the remaining fuel to space and then go in and deploy your gear.

A 'dry workshop' version of this was actually employed for building Skylab - they emptied the fuel tank from the upper-stage S-IVB engine and turned it into the workshop, adding the folding solar arrays and some heat shielding that ripped off during the launch, causing the first Skylab mission to be one of rescue and repair.

Re:I don't get it

[MachineShedFred]

Now only if there was some way to test some of the stuff you're griping about without sending it to orbit. Oh wait, all of it can be tested with facilities that already exist.

And why would any welding need to be done in space? We've already built a huge space station without it. Just make sure there are fittings already there before you launch it.

Can you do this with a bone-stock Atlas-V tomorrow? No, there would need to be some retrofit. But that retrofit will likely cost far less than multiple launches of Atlas-V rockets to put multiple payloads in orbit, if you can re-use the second stage tank.

This is why we have engineers "do the math" and figure out if it's cost effective or not, and they're far smarter than either you or I. Because they are literally rocket scientists.

Re:I don't get it

[Eunuchswear]

I like this bit:

Water can double as radiation shield. Put on a "slip on" jacket around the cylinder, assembled in 3-4 pieces, fill with water.
Now you have both radiation shield AND water supply.

'cos getting water into LEO is going to be so easy.

Re:I don't get it

[Whatanut]

I don't think anyone would argue that it costs nothing to do this. Nor would they argue that it's easy. The argument would simply be whether or not it's cost effective. Can it be done for less than the costs of launching a fully developed habitat from the ground.

That's the job of the company providing the work. If they can make it work, more power to them. If they can't, failed business model. If they can't and it gets funded through tax dollars as a huge boondoggle, then it becomes a problem for the masses.

Prove that it can't be done cost effectively. Not random "Oh sure!! That'll work great!!! No costs at all!"

Re:I don't get it

[bev_tech_rob]

Building big stuff in space doesn't make all that much sense yet. Building big on the Moon, makes a lot more sense and a lot of the raw materials are already there.

EXACTLY! We have built and launched metric shit-tons of equipment Earth orbit. Building on the Moon should be the next step. As mentioned, plenty of raw materials on the moon. There would be a one-time huge cost of delivering equipment up there for the first time. Eventually, a permanent infrastructure could be created and the equipment could be built there as well.

My .02 cents...

Re:I don't get it

[cat_jesus]

It's a damn shame they didn't do it with the shuttle external fuel tanks. Those things were huge. How many would we have in use now if that was part of the design?

Re:I don't get it

[cat_jesus]

At some point we're going to have to master welding in space. We might as well start learning that skill now.

Re:I don't get it

[pz]

It is pressure tested at many times the 0.5-1.0 atm pressure differential needed to sustain human life in space.

It is pressure tested on earth before being subjected to the intense rigors of launch. All bets are off as to whether it retains long-term integrity, as it has not been designed to do that. It's easy to find situations where a vessel will will not leak at high pressure differentials, but will leak at low pressure differentials. That we don't know the answer as to what will happen to the current designs is a good reason to test, but it should not be put forth as incontrovertible evidence of future success.

Re:I don't get it

[johannesg]

Dude, my job is doing thermal testing on spacecraft. I can tell you thermal design involves just slightly more than "wrapping a mylar blanket around it".

Also, the fact that rocket stages and habitats are both in some sense metal boxes does not in any way imply they are therefore interchangeable. Both are highly specialized parts that have very different goals. Rocket stages simply cannot afford all the extra weight necessary for them to function as a habitat (life support equipment, solar cells, meteorite shielding, access hatches, equipment for the astronauts to do useful work with, etc.). Besides, the biggest (lower) stages never make it into orbit anyway (only the top stage does, and why do you think that is?). The top stage is typically quite small. It's also not just a hollow shell; inside are multiple tanks (for fuel and oxidiser), the engine itself, pumps, electronics, etc. You'd have to remove all that.

So let's say you want to add all the necessary equipment later. How is it going to get into orbit? For that you need _another_ launch! And then you need to do a hell of a lot of precision engineering in one of the most hostile environments known to mankind, just to remove the old contents of the stage, and replace it by new contents which you might as well have launched ready to use from Earth (the weight is going to be the same, whether you pack it up tightly or not, after all).

You also have to come up with a plan to get rid of any remaining fuel. If it's hydrazine (not uncommon on upper stages), that's pretty toxic, and no, you cannot just open the hatch and hope it disappears into space.

Re:I don't get it

[Applehu Akbar]

"So an empty metal container made for storing fuel is also a great place to live? It has precisely the right properties in terms of structural integrity, heat and radiation shielding, etc.?"

Gee, if only H. sapiens were an adaptable species, capable of making do in extreme environments with available materials.

Re:I don't get it

[Applehu Akbar]

But at the same time, it would help a whole lot if tanks were designed with on-orbit adaptation in mind.

Re:I don't get it

[rgbatduke]

I'd think that evacuating the remaining fuel would be the least difficult problem imaginable to solve. As you say, hard vacuum. It's only tricky if you want to recover it (as both O2 and H2 might have some value of their own in space). Beyond that, pretty much any simple valve will work as long as you bleed it off slowly and watch out for Unintended Consequences (like thrust or vacuum refrigeration of the interior from adiabatic expansion).

As you say, not a new concept. But it is a far cry from try to re-engineer a Saturn V tank "on the fly" to become a space lab and designing a replacement for the Saturn V on the same general scale and with a similar but updated structure DEVOTED to putting up a modular space habitat in stable orbit (say, geosync) or at a lagrange point, or DEVOTED to putting together a similarly modular deep space exploration vehicle to travel to mars or even the moon.

If you are engineering a "Saturn VI" workhorse for these purposes, the entire second stage fuel system would be redesigned to facilitate the reuse of the tanks as part of the payload, and the payload would be, in fact, the rest of the required support system in some sort of snap-together modular approach. The tanks would probably have either completely removable ends or would have ends with large (say 2m out of 3 or 4) ports with a standardized sealable interconnect. I'm guessing (open and closed) interior ductwork would be built in (ultimately ported as needed inside and/or into the standarized interconnect). Some interior facilities might be preinstalled on the ground and capable of handling LOX or LH temperatures at high pressure. Some would await orbital assembly. But all the orbital work would likely be snap together stuff, not "this work requires a team of skilled laborers to install" stuff.

I'd expect assembly to be something like:

a) Shoot up the rocket, retaining the second stage instead of separating it; No humans needed. In fact, there would be no third stage -- what was the second and third stage of the SV would be all payload for the SVI.
b) In the desired orbit, bleed any remaining fuel or recover it into a much smaller tank, whichever makes more sense. No humans needed.
c) Robotically disassemble the outer shell as needed (which might be little or none). Remove all unusable hardware associated with its use as a propulsion system -- the actual rocket motor, fuel pumps, wiring and plumbing. Save what is (designed to be) incorporated into the new function (e.g. exterior wiring might well find new life as interior wiring if it was modular and movable, ditto pipes and perhaps some pumps). Probably save the rest as a "scrap pile" that could be used as a supply of raw metal that can be resmelted with a solar mirror in space, or not, whichever ends up making the most sense.
d) Robotically disassemble the "payload" on top of the tank, take off the top of the tank, and hook it onto a modular unit (possibly engineered to be a "collar" that fits onto the top of the tank) containing life support, power, an airlock or flexible interconnect designed to connect a series or parallel combination of tanks. STILL no humans needed to render the habitat at least marginally inhabitable
e) Finally, send up a crew (or deploy the crew that is already there in a growing structure) to do any final interior installations that the robots couldn't handle, fix problems, test everything thoroughly, and integrate the unit into a multiunit modular space station.
f) Along with any needed crew (rotation), periodically send up life support supplies -- fuel, air water, food -- and any tools and hardware needed. But I'd assume that one could send up and self-assemble many living/workspace modules that are then both inhabited and finished off or (re)furnished by one crew and supply shipment.
g) Once "enough" of them are assembled and interconnected at the desired orbital poi

Re:I don't get it

[CaptainLard]

There's this concept called engineering. Its very different from armchair engineering and political ranting, the core of this site. When applied correctly, engineering can solve many problems posed by a hypercritical, speculative and un-invested audience (/.), often in unique and unexpected ways.

https://en.wikipedia.org/wiki/...

Re:I don't get it

[rgbatduke]

Sure, pressure tested with HYDROGEN. Believe me, anything that holds hydrogen at 68 atmospheres should hold O2 at less than 1 (given the huge difference in molecular size), but yes, this is absolutely one of the design issues as the SV tank was designed to be loaded and then vent to hold the design pressure until launch, not hold H2 inside for weeks. Another one is that the tank itself only is structurally rigid enough to survive launch BECAUSE it is loaded with an enormous internal pressure, which makes the walls essentially rigid. OTOH even 1 atmosphere exerts 10^5 newtons per square meter, which seems enough to ensure substantial structural rigidity against far, far smaller thrusts. But still has to worry about whether or not it will substantially deform or rip if rorqued or dinged with an atmosphere inside and vacuum outside and somebody kicks a wall or hits it with a hammer or punctures it with a micrometeor, whether hydrogen embrittlement will occur in the comparatively short time it is loaded with hydrogen under pressure, whether (loaded) it can sustain unevenly applied end forces or torques, and so on. One might have to reinforce it on the inside with erector set circular beams and hang a lightweight interior shield to protect the outer shell and hide ductwork and facilities -- or not.

That is, I'm not arguing with you -- I AGREE that there is a lot of work to do on the subject, which is why I think the money being invested by NASA is well-spent. My only point is that there are some good reasons to think that it will be optimally cost beneficial to go this way rather than, as suggested by the top comment I replied to, a foregone conclusion that it is not going to work or turn out to be the best way to go. As many posters have noted, just because NASA opted at least partway out on this scheme with a Saturn V that happened to be available when a moon shot was cancelled doesn't mean that it has been properly researched or provisionally engineered with all of the things we've learned in materials science and electronics in the meantime.

rgb

Re:I don't get it

[aaarrrgggh]

You could conceivably have a module that inflates and expands inside the shell of the tank; it is much more viable than I thought just looking at the headline, although it isn't a slam-dunk proposition.

The real question is how much mass do you save for launching compared to a purpose-built device, and does that mass and velocity have a higher value than the complexity of re-assembling in space.

It will be interesting to see if it goes anywhere.

Re:I don't get it

[houghi]

The last question is: What do you have to do to the tank to FACILITATE this so that it isn't being done on an ad hoc basis?

That is not the last question. The last question is if it will be cheaper in monies, The development and testing of such things will not be nothing. You also need to look at how much space they need and what the running cost will be. It needs to be filled with oxygen. It will need to be cleaned and filtered and what not. Doing the change from something that hold very toxic stuff to something you cane live in on a spaceship is also what needs to be considered.

I can easily see that, for now, building a separate living environment is cheaper, even if the sending it up will be more expensive. It will be different if you are stating to build a colony, but for a lab it will be different.
It is not like a container that you ship somewhere with food and then let people keep it to live in.

Re:I don't get it

[johannesg]

The funny thing being, of course, that I actually do thermal testing on spacecraft and therefore have a good idea of what's involved in their construction, whereas you are presumably a pale basement dweller who has zero real-world experience of any kind but believes he knows everything because he has read about it on the internet once.

https://en.wikipedia.org/wiki/...

Re:I don't get it

[CaptainLard]

Thermal tester eh? Based on that last comment I was sure you were a demographic pigeon-holer forced into early retirement. Basement dweller you say? I wish! My basement has a drumset, wet bar, and a nintendo wii! Unfortunately I'm too busy with my day job*, that of an evangelical lobbyist with a primary focus on shifting federal policy to fewer rockets and more creationisim in school text books. As such I don't even need any real world experience because nobody fucks with the Jesus, fool! http://thebiglebowski.wikia.co... Now join me or fall into eternal damnation!!!!

*a funnier thing being, I actually supported a thermal-vac test for a SIBRS payload back in the day so you and I are two spacecraft thermal testers in a pod!

Re:I don't get it

[plover]

Bleeding off the excess H2 and O2 seems as wasteful as throwing away the tank itself. I would suspect that having an extra ton or two of oxygen and hydrogen wouldn't be all that hard to turn into an extra ton of H2O, which the crew might appreciate. Or if they send up multiple partially empty tanks, they could designate one tank as the recovery tank.

The tank purging process would probably be time consuming, but there should no reason to be in a hurry to convert the tank into a different usable space. Conversion is something the crew can do while under way to their final destination (with the reward of having an extra building to live in after they're all done; that should provide incentive to prioritize the task.) I would question the value of sending dedicated construction robots into orbit since the crew is already going to be there (unless the task has dangerous elements due to the residual fuel, risks of fire or explosive decompression while cutting openings into the tanks, etc.)

It definitely limits the main engines to burning hydrogen and LOX, though. There would be no way to purge a tank holding any of the other fuels they might want to use. Imagine if living in an empty diesel fuel drum was the best of the other available options.

Re:I don't get it

[pz]

I think you've hit the nail on the head. Nevertheless, I do want to point out that there is a simple case where a pressurized tank will hold just fine, but will leak like a sieve if the pressure is lowered: an internal flap that is being held in place against a hole by the high pressure, that is no longer being held sufficiently tightly when the pressure is lowered. The flap, in this case, might well be unintentional, like from an overlapped seam of two panels. It turns out that the flapper valve in most toilets works just in that way: it depends on the weight of the water to ensure a good seal, leaking terribly during the initial filling of the tank. The toilet valve is designed to do that, but after shaking the begeezus out of a lift stage that has been designed neither for low-pressure use nor for long-term durability, there might well be such flaps unintentionally present.

But the primary point is that we agree -- the basic idea is worth pursuing. Given the vast cost of lifting the shell to orbit, it would seem to be a resource that could be utilized, somehow, and that bears investigation.

Re:I don't get it

[Mike Van Pelt]

It's a damn shame they didn't do it with the shuttle external fuel tanks. Those things were huge. How many would we have in use now if that was part of the design?

A lot of people lobbied hard for that. My understanding is that the biggest barrier standing in the way was that the spray-on foam insulation on the external tanks would likely "popcorn" in vacuum, filling LEO with more little bits of debris. (I'm not sure where I read that; it was ages ago.) Junk in LEO is already a big enough problem.

Re:I don't get it

[rgbatduke]

It's like this. A dedicated construction robot eats sunlight, and breathes vacuum, or air, or H2 gas, or N2 or O2 gas as you ask. It, like honey badger, just don't care, as long as its batteries have time enough to recharge before its work shift. It can stay up in space for months or years without its bones deteriorating. Properly engineered, it is likely to survive all but the worst solar storms by just powering down and waking up again afterwards. It might even be able to repair itself, or if there were two, repair each other. And finally, if it "dies" for some reason the only loss is money -- no grieving relatives or national flag at half mast.

Also, there is little reason for a crew to be there before they are needed, and they might only end up being needed to move into the space habitat once it is constructed. I'm not religious about whether humans should or should not go into space -- I grew up reading Heinlein, Asimov, etc and think it would be lovely if they did, but then I learned physics and a certain amount of economics and a whole lot of computer science and programming and all I can say now is that robots make a whole lot more economic sense unless or until we are ready to make a serious commitment, such as building a large, permanent, 50's sci-fi style rotating space station at a lagrange point or in geosync orbit and sending people up to LIVE there, or LIVE on the moon. And that commitment would be extraordinarily expensive, and we haven't even taken care of business down here on Earth, such as ending world hunger and poverty and war so we can get on with trans-global progress and space.

Ten years ago, maybe, the possibility of robots doing all of the work might have still been fantasy, but at this point between AI robots and remote controlled drone robots, I doubt that there is much we cannot accomplish in space without risking human lives or spending the incredibly large multiplier on the amount of money required to do ANYTHING we want to do in space.

So at the very least I imagine it will end up making a lot more sense to build nearly everything with robots, even if humans do eventually come in to do their human "time for human judgement and creativity" thing, do things that are difficult to impossible to do remotely. And it isn't clear how large a set that will, ultimately, end up being. Even colonizing the stars seems a lot more likely to take place by sending our genetic instructions and raw materials and building an ecosystem from the ground up using robots as opposed to physically sending humans between the stars. We could afford to do ten colony starships of the former kind for one of the latter, if not more, and either way the original humans that leave the earth are not going to be the ones that first set foot on a planet circling another star...

rgb

Re:I don't get it

[DerekLyons]

It's a damn shame they didn't do it with the shuttle external fuel tanks. Those things were huge. How many would we have in use now if that was part of the design?

They didn't do it because the ET would have become the cargo - the Orbiter itself couldn't carry much beyond it's crew. On top of that, the altitude they would have been delivered to would have required regular reboosts. (Any tank launched before the turn of the century and not reboosted would be gone by now.) On top of *that* it required a number of dedicated Shuttle flights to lift all the stuff needed to outfit the interior.

In the end, using external tanks was very, very expensive for very little functionality.

Re:I don't get it

[RockDoctor]

I would suspect that having an extra ton or two of oxygen and hydrogen wouldn't be all that hard to turn into an extra ton of H2O,

This is an exothermic reaction. You want to be careful starting those on Earth, where "run away" is an option. You're even more careful about starting them at sea (I work on offshore oil rigs ; trust me on this, or I'll start to talk about the Hot Work Permit system!), where "run away" has a good chance of being followed by "die of hypothermia or shark attack". You're even more careful in the air (see all the stories bout laptop batteries in particular and lithium ion batteries in general). For space ... What did rgb@duke say earlier about "unintended consequences"?

they could designate one tank as the recovery tank.

Having been RTFMing for the Atlas-Centaur system, the Centaur tank is a single stainless steel (OK - NASA speak of "corrosion resistant" steel ; I just bet there's a story behind that. Possibly a blood-stained story. Or maybe a red-fuming-nitric-stained story?) tank body with an internal partition of fibreglass (ugh, sorry Dad! "GFRP") honeycomb which separates the LOX and LH2 sections. Now ... there should be some way to guarantee (or control, actively) the pressure differential across that partition. And already you can see the complications of re-filling one tank from multiple others. Please remember that LOX and LH2 have boiling points 70K apart (at atmospheric pressure) and I dread to think how different their specific latent heats of vapourisation are, or their specific heat capacities.

Doable, I'm sure. Simple, I doubt.

explosive decompression while cutting openings into the tanks

That does not seem to be on the agenda, ever. It's a damned sight harder to close a hole than it is to route cables, hoses etc around the problem.

Just haing a think ... I'd consider procedures like wrapping the exterior of the tank with multi-wall plastic film tubing (here's a concept I was examining for work a while ago) then filling it with water - e.g piss - and letting it freeze for both micrometeorite protection, thermal and radiation insulation. Then cut the LOX-LH2 baffle from the sides, slide it down to the far end and re-glue. Then start to build up unpressurised partitioning as desired, gluing stuff to the wall.

The design NanoRacks are talking of is to build, effectively, a different Centaur-to-payload adaptor which incorporates a pressure door (to keep the LOX in the tank on Earth), and to have a module with a NASA dock, an ISS dock, a Centaur dock, and then the actual planned Centaur payload mated to that. (Check the Atlas User Guide for information on the 3 existing Centaur-Payload Adaptors) Then the payload module is mated to the ISS as planned and the Centaur tank re-mated to it's mounting point using the ISS's arm.

It certainly looks an interesting idea.

Re:I don't get it

[RockDoctor]

And finally, if it "dies" for some reason the only loss is money -- no grieving relatives or national flag at half mast.

Grieved though I am when one of my colleagues is killed at work (only a couple dead this year), I've yet to see a case in which any flags went to half mast. Besides, whose flag would you lower? The worker's nationality? Their country of origin? Their cultural identity? Their employer's nationality? The ISS's (or other vessel) "flag of convenience" for insurance purposes (I assume that like every other American vessel I've been on, the ISS is flagged in either Panama or Liberia for tax reasons. And the crew are 30% American, 70% Filipeno? For wage packet reasons.)

50's sci-fi style rotating space station at a lagrange point or in geosync orbit and sending people up to LIVE there

But, but, but, that would involve learning how to live in an environment without polluting it. We can't do that - it'd pander to the global warming socialist conspiracy to even consider the possibility of having to pay attention to the environment.

Seriously - seeing all the problems consequent on trying to live in microgravity, one very obvious answer is the old "Doctor! doctor!" joke :
Patient : "Doctor, doctor! It hurts when I do X!"
Doctor : "Then don't do X."

It doesn't have to be a 2001-style "torus" station (to start with). A nuclear power plant (or solar panel array) at one end of a tether (rigid, flexible, or whatever) and human volume at the other end ; rotate. Then add modules one at a time. (Two at a time for the first few.) All it needs is power (which the local thermonuclear power plant provides, one photon at a time), reaction mass and building material. The latter probably requires capturing an icy asteroid, or muddy comet, but I personally think that would be a really really good technology to have practice at doing, before we need it in a hurry. See signature line. The aviation programme of the dinosaurs saved them from extinction, but if they'd had an asteroid-moving space programme, we'd probably all be speaking Brontosaur. And be watching the North Atlantic start to open.

Re:I don't get it

[RockDoctor]

somebody kicks a wall

See "Doctor" joke upthread. Don't do that.

or hits it with a hammer

[Searches toolbox] "Nobody sent us a hammer!" [Radio to mission control] "Can you send up a hammer in the next tool shipment." [Mission control] "No. Next question?"
Seriously, [Myself on an oil rig 3km above the Atlantic mud, off the African coast] : "Your equipment is giving suspicious results. Pass me your multimeter so I can check if it's working properly."
[Service company rep.] "Our office will only send out a multimeter if it is accompanied by a technician. Technician visits requested by the client are billed at $1500/day."
[Self leaves problem on the table. Returns to office. On night shift with junior service company rep on duty, I take out my multimeter, teach him how his equipment works and how to fix the problem. Next morning, senior service company rep is annoyed and his Boss onshore is furious at losing $5000-9000 of technician fees. Client (who hired me) is happy at not paying the fees.]

or punctures it with a micrometeor,

See my comment upthread about coating the outside with ice bags (sorry - Slashdot-ism : "frosty piss bags"). They won't stop all meteorites, but will certainly stop a lot of them. While also providing both thermal and radiation insulation.

We live at the bottom of an atmosphere approximately equivalent to 10m of (liquid) water, and are evolved to handle that level of radiation. Every mm of water (or equivalent) that we can put outside the space habitat helps towards the goal of radiation dose management.

Re:I don't get it

[RockDoctor]

'cos getting water into LEO is going to be so easy.

A fair enough point. Of course, getting water from the asteroid belt isn't likely to be free either. But if only there were some other reason for learning how to move overgrown dirty snowballs around in space ... like the dinosaurs didn't.

(No, it's not certain that the Chicxulub impactor did for the non-avian dinosaurs - see signature ; I've been following Gerta Keller's work for over a decade - but it sure as hell wasn't a good day for anyone on the planet. Really, knowing - by having done it - how to move multi-kilometre natural objects around in space would be a damned useful skill for a species with a desire to see the distant future. If you're American, you could spend an educational day wandering around in the desert 20-odd miles W of Winslow, Arizona picking lumps of nickel-iron out of the ground and waiting for the 10 megaton energy release. Actually, at 10 megatons, it wouldn't matter much if you walked around in the desert, or sat in a diner in Winslow. Bad hair day, either way.)

Re:I don't get it

[RockDoctor]

Your reasoning leading up to "we're going to have to master welding in space" is?

You may be right. But I don't see it as automatically being the case that welding would automatically be stronger, quicker, cheaper or more effective than, say, gluing. We do have some pretty effective glues, for example, and in space, you don't have an oxide or moisture film forming after you abrade the surfaces to join.

Re:I don't get it

[Eunuchswear]

If you can move comets the last place you'd move them to is LEO!

Re: I don't get it

[Eunuchswear]

There isn't much leftover H2 or O2 -- no point im wasting the energy putting it into orbit.

Re:I don't get it

[RockDoctor]

If you need reaction mass, possibly material for making rocket fuel, non-volatile comet debris for soil and radiation shielding (*), the first place you'd move them to is "near earth". Not directly to LEO though - the cost of moving water or tanks between LEO and (say) Earth-Moon L2 or L3 is far lower than the cost of moving the same mass of water from Earth's surface to LEO. Of course, you'd have a staging area in space (three degrees of freedom) and velocity (another 4 degrees of freedom) for delivery of the dirty snowballs. The precise orbital details vary from comet to comet (or asteroid to asteroid - they're a continuum. See recent discoveries from the Dawn spacecraft.), but you can plot courses from "there" to "here" which use an interaction (or several) with the Moon to minimise the necessary delta-vee, and those lead to the incoming objects congregating around the L2, L3 points. The details change from orbital object to orbital object.

Scatter-gunning LEO without any planning - in exactly the casual way that NASA does at the moment - with comets launched randomly from the snow line, is likely to end badly for someone. But some of these NASA boffins are using a controversial new theory from some English alchemist called "Newton" (obviously an Apple fanboi), and they claim they can plan orbital transfers in considerable detail. Which is stupid, because that would imply that we'd know if the Sun was going to rise tomorrow, or whether a dirtball 7 light-hours away was going to occult a particular star years, before the event.

(*) all of these are things which will be needed, in abundance, for humankind to have any long term (say 100kyr +) future in space. Given the geological record, that duration would have around a 5% chance of having a km-scale object impacting the Earth.

NanoRacks

[Gravis Zero]

I guess tinytits.com must have already been taken. ;)

Re:NanoRacks

[reboot246]

I was thinking the same thing and was looking to see if anybody had posted it. If I had mod points today, you'd have one of them. +1

Thanks for the laugh!

Oh, ATLAS V...

[SeaFox]

For some reason, when I was reading the summary, I kept reading it as "Saturn V" and I was like "since when is anyone building those anymore?"

Re:Oh, ATLAS V...

[GuB-42]

Well, maybe because NASA considered this with Saturn V for Skylab.
Finally if was deemed more effective to build to station on the ground entirely rather than to recycle the used fuel tank.

Re:Oh, ATLAS V...

[LWATCDR]

Actually Skylab was built in a fuel tank. The the idea was to launch it using a Saturn Ib but a Saturn V was used because one was available. BTW that s why the the floors of Skylab where an open grid. There was even a plan to put a Skylab in orbit around the Moon.

Re:Oh, ATLAS V...

[HornWumpus]

I doubt that. Cite please.

SSTO is a big deal.

Protection

[maroberts]

As I recall the inflatable module has a multilayer lining to protect from radiation and micro meteors and other stuff. I don't recall fuel tanks having the same concerns. Also the inflatable module used for comparison is a prototype and full size inflatable modules will be substantially larger.

All in all I don't see how a second stage tank will compete.

Re:Protection

[Anonymous Coward]

Or you could make it a habitat first, add all the shielding for radiation and micro meteors even add some live support systems.
Then just fill the habitat with fuel.

Re:Protection

[Rei]

Because all of the hardware that goes in a habitat is just totally compatible with being submerged in liquid oxygen and/or liquid hydrogen?

Re:Protection

[Rei]

Right, so they're going to reengineer every last subcomponent of every last part to withstand cryogenic temperatures, specifically for production in the tiny volumes needed in the space industry? Just for the inconvenience of reusing an upper stage?

Again: contrary to would-be-rocketeer imaginations, launch costs are not the be-all end-all of expenses when it comes to space. Engineering and low-volume production is killer. Mission designers always heavily stress TRL (Technology Readiness Level) of all components, as it's such a key determiner of mission cost. If any plan you propose involves "just reengineer everything", you do not have a plan.

Re:Protection

[PReDiToR]

Put the sensitive bits in sandwich bags and cable tie them off.

I mean, you could use duct tape but where's the fun in that? Not every engineer at NASA is qualified to use it.

Too bad they can't use the SS ext. tanks

[wisebabo]

Too bad it's too late for them to be able to use the Space Shuttle external tanks.

There were around 135 launches (so I guess the number of tanks that made it almost to orbit would be 134). Of course many (most?) of these missions were not in the correct orbital plane for use as space habitats (I guess they would not be easily reachable by subsequent manned flights). Still when one considers the sheer volume (about 2 million liters!) you'd think they'd be very useful. Also because they didn't have much heavy external hardware (like engines) they'd be easier to move around and keep in orbit.

What could they have been used for? I'm not sure but a whole bunch of interesting applications come to mind. If they could hold a full atmosphere's worth of pressure they'd make huge living spaces. If only a low pressure environment could be maintained, perhaps plants could survive in a mostly CO2 atmosphere; with a slow rotation about the long axis and a central light column running down the length of it, it could be a huge hydroponic garden for waste recycling and food. If they turned out to be pretty durable then perhaps propellent storage or even reuse as fuel tanks for interplanetary expeditions could be envisioned. Since they are light, perhaps they could be sent, empty, to a passing comet to refill with water and then sent back to earth orbit using some of the collected mass as fuel. If nothing else, they could have been cut up and used as raw materials for use in providing shielding against micrometeorites.

Anyway, there were well over a hundred of these giant things that, with just a little more delta-V (and admittedly, long term boosting to counteract atmospheric drag) could have been a valuable orbital resource. I guess it wasn't done because some infrastructure wasn't available (cheap orbital "tugs" perhaps using ion drives for low fuel consumption) and the vision and political will wasn't there. Too bad because this could've been like Skylab but hundredfold.

Re:Too bad they can't use the SS ext. tanks

[Rei]

Shuttle ETs never got up to a stable orbit. It would have been possible to use the OMS to take them up there, but then the Shuttle would have had basically no payload capacity on that mission.

Of course, that's one of the lesser problems with the concept. Often proposed, often investigated, but never considered worth throwing serious money into.

Re:Too bad they can't use the SS ext. tanks

[Mike Van Pelt]

Shuttle ETs never got up to a stable orbit. It would have been possible to use the OMS to take them up there, but then the Shuttle would have had basically no payload capacity on that mission.

On that issue, the shuttle actually used the OMS engines to steer the ET into a quick re-entry, then dropped it and used the OMS engines to get into the orbit they wanted. They used extra fuel to do this. (This doesn't address the other issues with the concept, of course.)

Re:Too bad they can't use the SS ext. tanks

[DerekLyons]

Shuttle ETs never got up to a stable orbit. It would have been possible to use the OMS to take them up there, but then the Shuttle would have had basically no payload capacity on that mission.

And even then, the tanks would be low enough to require regular reboosts. Without reboosts, any tanks launched before around the turn of the century would already have re-entered.

Idea from the 1960s

[Anonymous Coward]

The concept of a Wet workshop (reuse an upper stage as a habitat) was first proposed by Wernher von Braun in the early 1960s.

Nonsense

[DerekLyons]

From the interview: "The reason that Skylab wasn't build like this is kind of a strange story: [NASA] had fewer Saturn IBs than they had Saturn Vs, so von Braun just decided to use a Saturn V and fly up a "dry" lab, with all of the equipment aboard it already."

Um, not quite. When a 'spare' Saturn V became available (because a lunar mission was cancelled), they swapped from a IB 'wet' lab to a V 'dry' lab because the 'wet' labs were very expensive for their very low capability. The expense came from needing to have considerable amounts of structure and infrastructure designed to survive inside the cryogenic conditions inside the tank, from redesigning the tanks to serve a dual role, and then re-certifying the whole deal for flight. The low capability came from the requirement that everything that couldn't survive a bath in deep cryogens having to be manhandled into place via the very narrow docking hatch. While a dry lab was more expensive than a wet one - the leap in capability was far greater than the leap in cost.

That's also why NASA built their ISS modules with the large CBM hatches - manhandling large amount of stuff through tiny hatches (like those the Ixion will use) simply isn't very efficient. (And that's without considering the headaches that splitting all your equipment down into tiny chunks brings. Not just handling - but installation and integration too.) All of the ISS cargo craft that NASA is responsible for uses CBM, as does the Japanese HTV.

"In the commercial sector, it's getting interesting, because people are taking more risks. Not unnecessary risks, but acceptable risks to reduce costs."

Moving your man hours (outfitting the module) from expensive ones on the ground to hellishly expensive ones on orbit is not a recipe for cutting costs. Especially since you still have to pay for the launch of the module (Centaur) *and* the launch of the stuff to go inside it. (You can't piggyback because no Centaurs are headed anywhere near the ISS.) Even in lower inclination orbits, the mission module, the rendezvous systems, and outfitting the Centaur to survive years on orbit are all going to cost money and cut into it's payload - which will make piggybacking unattractive to Centaur's usual customers.

"We want to keep hardware costs as low as possible: it's not about building something on the ground that could cost hundreds of millions of dollars. Why do that when you have perfectly good hardware going to space, paid for already?"

You don't have perfectly good hardware going to space already. You have a vehicle designed for a completely different purpose and completely lacking the "stuff" customers will pay you for going to orbit.

Or, in short, nothing in the article or interview leaves me with a warm fuzzy that they've solved any of the well known problems with 'wet' systems.

easy peasy

[Anonymous Coward]

This must be easy.
1) Construct the habitat/fuelcontainer here on earth.
2) Put a big plastic bag inside and fill the plastic bag with rocket fuel.
3) When in space, attach the habitat to ISS and rip out the plastic bag.
4) Open all windows for a while to remove any remaining smell of rocket fuel.

Re:easy peasy

[Rei]

What plastic are you thinking of and at what thickness, that is compatible with liquid oxygen, retains flexibility at LOX (or worse, LH) temperatures, and withstands the pressure, all without adding a massive mass penalty? How is the plastic supposed to deform around every little structure in the habitat (aka, not face multiple atmospheres of asymmetric pressure)? What sort of hardware are you thinking of where every last element is just fine with being frozen down to LOX (or worse, LH) temperatures? How many man hours are you thinking of to "rip out" the giant bag through the tiny docking port (after having to detach it where it's carefully bound around each element? Unless you were thinking of having it fully loose inside there, which is even more problematic. Where's it supposed to go on the ISS? If you're doing the (larger) hydrogen tank, how 100% sure are you that you're not making an explosive fuel-air mixture, given that hydrogen burns at just a couple percentage concentration? How positive are you that you've fully vented every last nook and cranny? And on and on and on.

Wet workshops were worked on during the Apollo era. They were ditched for dry workshops because it's easier, cheaper, and more functional.

Re:easy peasy

[RockDoctor]

If you're doing the (larger) hydrogen tank, how 100% sure are you that you're not making an explosive fuel-air mixture, given that hydrogen burns at just a couple percentage concentration?

Well, for the actual system they're considering, it's the larger (volumetrically) part of a single tank, the LH2 and LOX being separated by a "fibreglass honeycomb", which I guess is glued in place after welding together the bottom end of the tank and the main length of the tank body, but before welding on the top end. I'm not sure whether the LOX is in the upper or lower part of the tank.

Unlike most people here (and I think you and I have discussed this before), I've worked with hydrogen gas too (in analytical instruments), so I appreciate what you're saying about it's flammable limits. What I'm wondering is - with relatively minor modifications to the tank's structure, would it be workable to get rid of the dregs of the fuel by pumping O2(g) into the H2(g) headspace of the tank and lighting a flame of O2 burning in hydrogen. So you approach the UEL of [H2] from the other end, and you have your oxygen going into a mix of H2(g) and H2O(g). Any water that condenses out is uninteresting from an explosion safety point of view. For maintaining the desired pressures in the tank, you'd need an inert pressurising gas - N2 being where I'd start from (might need He for thermal reasons ; meh).

Plan B might be to install a mixing fan into the H2 tank which was covered in Pt-coated wire wool, and to use that to agitate the gaseous contents of the H2 tank, again while bleeding in O2. Monitor tank temperature (Pt-resistance wire as in a kathaometer, perhaps ; kill two stones with one bird?) as the Pt assists the reaction ; if it gets too warm, turn off the O2 supply and let some of the water condense out. Again, make efforts to avoid ever having an atmosphere in the tank that isn't a mix of H2(g) and H2O(g).

I bet the procedures for filling a newly-made tank with it's first charge of LH2 are a real fun read. I don't recall anything about it in "Ignition!" - but that concentrated more on exciting fuels like red-fuming nitric and the "mythical monoprop" and less on dull, pedestrian fuels like LH2/LOX.

I'm tempted to change my signature to : 'monopropellant' is an anagram of 'explosive' for all important meanings of "Kaboom!"

Re:Stupid

[ledow]

There's lots of research demonstrating that long periods of time spent near campfires cause serious health issues. Absent cleaning the air, such as with a complete air-conditioning and filtering setup, it is unhealthy for humans to be near a campfire for any significant length of time. ... so this isn't viable.

It's about risk. The risk of you cooking your food (thus exposing you to carcinogenics) compared to the risk of eating uncooked food (which we did for MILLIONS OF YEARS) is a trade-off.

Do you sacrifice those temporary, mostly reversible health issues (comparatively vanishingly small compared to the general risk of take-off and space travel in general, to be honest) for the opportunity to live and work in an entirely new environment?

To be honest, mining is an incredibly dangerous profession. Scouting the bottom of the oceans too. Diving near oil rigs. All of these things are MUCH HIGHER RISK than the health effects of prolonged space travel. And people do them every single day.

Even simulated gravity doesn't solve the problems of space travel, so even your solution is completely useless in terms of combating all - or even the significant - health risks. Radiation would be the killer, long-term.

To be honest, there are thousands of people, most of them sane, educated and intelligent, willing to sign up to a one-way mission to Mars.

In the same way that for centuries, people fought to get to the top of Everest or to the middle of the arctic poles. Of course it wasn't without risk. It can't be. But that's how you discover the risk, reduce them and compensate for what you can't reduce.

So re-using a fuel tank as a habitat in space is just one sensible method of reducing risk - of having to send up more junk to live in, so you don't have to live in cramped conditions, or needlessly spend money on more accommodation when you could spend it on safety gear or fire tests or whatever.

Didn't Proxmire keep this from happening ?

[Salgak1]

. . I've heard the story, on and off over the years, that Sen. William Proxmire stopped funding for NASA studies on taking the External Tank into orbit, and using it for the basis of a Station.

But I can't seem to find an actual reference, anybody seen one, or is this an Urban Legend of the Space Program ?

This is the exact opposite of new

[larwe]

Skylab came out of a set of proposals that included exactly this kind of "wet" (because formerly full of fuel) habitat. https://en.wikipedia.org/wiki/...

"Tank Farm Dyname"

[dpilot]

Story by David Brin, using Shuttle external tanks. Whaddya know, the whole story is on the web: http://www.davidbrin.com/tankf...

Re:"Tank Farm Dyname"

[Dareth]

Thanks for the post. I really enjoyed reading that. I was wondering why all the yeast until they got to the ale/beer part.

Re:"Tank Farm Dyname"

[sconeu]

Don't forget Kim Stanley Robinson's Mars series. The Ares was essentially built from Shuttle ETs.

Re:65 million?

[BlueStrat]

Just imagine how much we could accomplish with all that welfare money? (3 trillion a year).

Where are your priorities, man!?

Don't you realize that $3T is what keeps the status quo the status quo and contributes heavily to a 90%+ incumbent reelection rate?

Why, I just heard about the new program being proposed by the administration to help quell the recent riots. It's sort of a spin-off from the 'Cash For Clunkers' program.

They believe that access to safe and stylish transportation will both assist in their financial mobility but also in bolstering self esteem.

They've floated a few possible names for a vehicle giveaway program for inner-city "justice-involved" individuals at risk:

"Caddies For Baddies"

"Navigators for Violators"

"Lugs For Thugs"

"Escapes For Rapes"

They briefly considered but abandoned an identical plan with motorcycles for those involved in gun violence they considered calling "Scooters For Shooters".

Strat

Toxicity

[fox171171]

Isn't the contents of the tanks kind of nasty? Will opening the tanks to the vacuum of space be enough to evaporate it all out?

Re:Toxicity

[RockDoctor]

If the tank is in low orbit then gas can be concentrated and blown to the bottom of the tank and allowed to escape from the top.

Even in low orbit (i.e., where the drag is sufficient to de-orbit the tank within a couple of years), you're still in what on Earth would be considered a really hard vacuum.

Re:Toxicity

[RockDoctor]

Isn't the contents of the tanks kind of nasty?

You're probably thinking of things like hydrazine, or some of the hypergolic mixtures. (A and B are "hypergolic" if mixing A and B results in explosion in milliseconds without needing any initiator, detonator etc. Very good if you want your motor to re-start reliably. The explosion delay is an important characteristic. Milliseconds matter.)

The main fuel in the Centaur stages under discussion are liquid hydrogen ("LH2") and liquid oxygen ("LOX"), but the reliable re-ignition of the engine is controlled by what they refer to as "hypergolic cartridges" - see the engine schematic on page 377 of the Atlas (RT)FM.

Whatever hypergolic mix they use, you don't want to get that shit mixed up with your "intimate lubricant".

"Firestar"

[Daetrin]

As long as we're sharing related SF, see also Michael F Flynn's novel "Firestar" and its three sequels. It's basically a series about a Space X-like company that wrapped up the year Space X was actually founded, and has the reuse of fuel tanks as habitats as a side note.

And in response to all the people saying that the cost of either modifying the tanks to server dual purposes or performing additional construction in space makes it infeasible you're probably right. If we were talking about a one time deal. However if we ever get to the point where we have enough people in space that we need to start doing construction work anyways the economics will seriously change, so it's not unreasonable to start looking into it now. And if nothing else just the materials alone might be well worth the small cost to boost the tanks a little higher, even if they end up just getting disassembled for parts and raw materials.

Re:A "habitat"?

[Pseudonymous Powers]

Poor people in India harvesting feces from the sewers have a better habitat than living in a fuel tank in free fall.

Just give them time, Space Nutter Troll. The feces will come, the feces will come.

Book

[blackomegax]

This was a minor plot in some scifi novel from the ~90's. Damned if i can remember the name though but they built a large station out of used space shuttle tanks.

Better than junk

[rickb928]

Which they are now, orbiting junk, and a hazard as long as they drift along.

But recycling them offers an opportunity to raft a few together, build a new, viable habitat, and reduce the clutter.

Oh, and when do we send up the garbage scows to harvest the real junk and delitter the low orbits?

Why not make server farms?

[RogueWarrior65]

Why not use these as server farms? Solar power would be easy. Microwave comm link. No need to waste energy cooling it.

Re:Why not make server farms?

[Nethemas the Great]

A solution chasing a need.

Re:Why not make server farms?

[RockDoctor]

It costs energy to move heat. Expending energy generates heat. Moving heat generates heat.

Condensed version of the Laws of Thermodynamics : you can't win ; you can't break even ; you can't stop playing ; absolutely everything is subject to the Laws of Thermodynamics, including specifically anyone who objects to the tyranny of the Laws of Thermodynamics.

storage, not habitat

[Rob Bos]

Surely they could be used as storage tanks, instead of living spaces. I doubt they'd be rated, after the stresses of launch, for long-term habitation, but there's going to be ample need for the bulk storage of mass. One of the sad things that is done, is the jettison and burning of trash; perfectly good organics and mass that might be someday useful in orbit, when the technology is developed to make use of them. Then the containers themselves could be used as raw material for some hypothetical future process.

Whether it's worth the investment is another question entirely, though the existence of a tank full of vacuum-dried sewage co-orbiting the ISS might inspire some thinking about what to put it to use for.

The investment, unfortunately, would also have to include the cost of periodic reboostings, keeping it all fastened together, keeping it balanced along a thrust vector, and several other considerations. It could get very expensive to maintain that orbital junkyard as a future investment, which may or may not even pay off.

Re:storage, not habitat

[RockDoctor]

I doubt they'd be rated, after the stresses of launch, for long-term habitation,

Is anything at all "rated" for long term habitation in space. You'd never get the physical ailments consequent on a 6-month spaceflight past any industrial safety laws. Seriously, not.

but there's going to be ample need for the bulk storage of mass.

You've gone from step 1 to step 100 without showing any of your intermediate working. This blank assertion does not convince me. Would you fill in a few of the steps by which you arrived at that assertion.

perfectly good organics and mass that might be someday useful in orbit, [...] Then the containers themselves could be used as raw material for some hypothetical future process.

Hmm. "GIGO". Not "garbage in, garbage out," but "getting it in and getting it out". Unless you're *only* talking about sewage. But having had to unblock the family shitter more than a few times after the sister blocked it with nappies (EN_US : diapers), I don't relish that task in zero-g. "Who'd use diapers?" I hear you say. Well, having friend who are saturation divers, and never once having heard someone on a spacewalk tell ground control that they need to go inside for a shit ... I think that every EVA, particularly the 6-, 7-, 10- hour ones has generated a moist nappy, and probably one full of shit.

Tanks are good for getting liquids and gasses in and out ; for pastes and solids, not so good.

Also, for long term storage, you're either going to need a gas venting system (in which case you've got a rocket effect which you've got to control ... more complications) or you're going to need to mix "biocide" with it in appropriate amounts. Then, when you want to re-use it (e.g. to manure your eating plants) you need to neutralise the biocide before it kills your carefully maintained microbiological environment.

What is that "zeroth law of science"? Oh yes, "It's not as simple as that."

Undatable!

[Anonymous Coward]

In my day, the girls with nano racks were undatable.

This is ...

[PPH]

... the outer space version of people who want to convert shipping containers and pallets into micro houses.

Re:Stupid

[Nethemas the Great]

You mean like this?

Old idea

[PinkyGigglebrain]

Back in the late '80s there was talk about having the space shuttle hang on to the big external fuel tank until it got into orbit. The idea was the tank could be modified on the ground to have a docking port and basic necessities like basic ventilation ducts and electrical harness already installed. Since the shuttle almost never had anything near its max cargo load the added weight of the tank would not have been an issue for the shuttle to get into orbit. Sadly the idea never went anywhere.

Parts for a Big Wheel

[gslj]

What I'd like to see is

Send up a hub.
Slot the used Centaurs into the hub as spokes
Connect the spokes on the outside rim
Spin 'er up as a rotating wheel space station.

You've always known you want one of these!

Re:Right Idea, Wrong Booster

[HornWumpus]

In LEO thicker walls are worse from a radiation perspective.

They aren't going to stop high energy cosmic rays, but will throw off tons of more dangerous secondary particles. You want the cosmic rays to just go through, not scatter a bunch of secondaries.