Inflatable module for ISS

[Kibble]

Kibble, you seem to be really intent on shooting down the very idea of this before it's even been tested. Reasoning?

I was just convinced by various sources that in most cases inflatables won't be the best solution. Almost anything where you can ask a question starting with "why don't we just", there's a reason (or several reasons) why we don't just. A particularly similar example to inflatables is nuclear-thermal rockets. It just complexes stuff up with little benefit.

[Bill Phil]

I was just convinced by various sources that in most cases inflatables won't be the best solution. Almost anything where you can ask a question starting with "why don't we just", there's a reason (or several reasons) why we don't just. A particularly similar example to inflatables is nuclear-thermal rockets. It just complexes stuff up with little benefit.

We don't use inflatables because they're not funded. That and they haven't been proven. Might as well prove them, then.

[Kibble]

We don't use inflatables because they're not funded.

Essentially everything ​we don't do is because its not funded

[Bill Phil]

Essentially everything ​we don't do is because its not funded

Yeah.

The concept evolved from TransHab, which is from the 90s.

[vger]

Almost anything where you can ask a question starting with "why don't we just", there's a reason (or several reasons) why we don't just. A particularly similar example to inflatables is nuclear-thermal rockets.

That's not a fair comparison. We're not using nuclear-thermal rockets because nobody feels comfortable with nuclear devices floating around in orbit. It makes certain countries far too nervous, whether it's logical or not.

Obviously the idea is sound enough that they're willing to experiment with it.

[Kibble]

We're not using nuclear-thermal rockets because nobody feels comfortable with nuclear devices floating around in orbit.

Well that's one very practical reason, but I was referring to the technical reasons we don't fly nuclear-thermal rockets - it's immature, complex, and offers little benefit over traditional rocket engines. Inflatables are immature, complex, and offer little benefit over traditional aluminium cans.

[Bill Phil]

Well that's one very practical reason, but I was referring to the technical reasons we don't fly nuclear-thermal rockets - it's immature, complex, and offers little benefit over traditional rocket engines. Inflatables are immature, complex, and offer little benefit over traditional aluminium cans.

Nuclear Thermal rockets could be mature, if we had developed them... Not to mention double the Isp over the best chemical ones.

The expandable modules are immature, yes. But they are actually a little less complicated than the tin cans. Their benefit over traditional tin cans is that their mass to volume ratio is much bigger. Getting a volume similar to that of Mir in one launch, compared to 6 for Mir.

BA 330: ~ 60 kg to a cubic meter

Mir: ~370 kg to a cubic meter

See the difference?

Edited March 15, 2015 by Bill Phil

[EzinX]

Nuclear Thermal rockets could be mature, if we had developed them... Not to mention double the Isp over the best chemical ones.

The expandable modules are immature, yes. But they are actually a little less complicated than the tin cans. Their benefit over traditional tin cans is that their mass to volume ratio is much bigger. Getting a volume similar to that of Mir in one launch, compared to 6 for Mir.

BA 330: ~ 60 kg to a cubic meter

Mir: ~370 kg to a cubic meter

See the difference?

How much does this really help? You need equipment to do experiments, water and food and oxygen for the astronauts, rocket fuel : all this stuff has the same mass independent of internal volume. Did NASA launch entire modules for the ISS solely for the purpose of boosting interior space?

[Kibble]

double the Isp over the best chemical ones.

I'm awful at math, but calculations by legendary mathematical artist Hop David say the extra ISP doesn't have that big a benefit. That's beside the point though

The expandable modules are immature, yes. But they are actually a little less complicated than the tin cans. Their benefit over traditional tin cans is that their mass to volume ratio is much bigger. Getting a volume similar to that of Mir in one launch, compared to 6 for Mir.

How are they less complicated? They are made of several layers of various materials that have to be able to collapse into a small volume, and be rigid and strong when pressurized. The interior has to be manually assembled, furnished, and supplied, so it isn't habitable immediately after launch, and you can't have things mounted on the exterior, unless you spacewalk and put them there.

[RainDreamer]

Expandable just allow us to launch bigger stuff to space with less cost. And it save us design headaches either trying to fit a bigger payload into a fairing, or having to split that payload to multiple smaller payload and dealing with assembling them together.

So why launching such big, empty module? One of the motivation was for preparing commercial space flight. We can create private space hotels, space research facilities, and well, maybe if someone can afford it and want to live there, space houses. Those people probably want some leg room. Equipments can be later 3D printed, or installed inside easily.

Is it efficient? Who knows. We have only seen like two test modules by Bigelow sent up to space. They look promising, but since those are information from bigelow themselves, there are reasons to doubt.

I don't think inflatable will be the one solution to end all problems, but I think more options in design, when used correctly, can allow better results than sticking to one type of design only.

[Bill Phil]

How much does this really help? You need equipment to do experiments, water and food and oxygen for the astronauts, rocket fuel : all this stuff has the same mass independent of internal volume. Did NASA launch entire modules for the ISS solely for the purpose of boosting interior space?

That 20 tonnes of the BA 330 accounts for the life support.

- - - Updated - - -

I'm awful at math, but calculations by legendary mathematical artist Hop David say the extra ISP doesn't have that big a benefit. That's beside the point though

How are they less complicated? They are made of several layers of various materials that have to be able to collapse into a small volume, and be rigid and strong when pressurized. The interior has to be manually assembled, furnished, and supplied, so it isn't habitable immediately after launch, and you can't have things mounted on the exterior, unless you spacewalk and put them there.

Twice the ISP equals twice the Dv. Beyond the Ln part, it's all basic math.

They're less complicated because you don't set up the interior at all. It doesn't need to survive launch in that particular arrangement.

Do you know what habitable means? It means you can use to live there. And there's a core center to the BA 330. It could put quarters in their. And they'd be small mass wise. There, it's habitable. But anything that's more luxury tuned would need to be launched separately. Heh, "Sold Seperately"...

[Kibble]

Do you know what habitable means? It means you can use to live there. And there's a core center to the BA 330. It could put quarters in their. And they'd be small mass wise. There, it's habitable. But anything that's more luxury tuned would need to be launched separately. Heh, "Sold Seperately"...

What I meant was, once you put it up there you can't launch astronauts up to live in it. It has no consumables, no furnishings, nothing to do, no beds (like those sleeping compartments). It takes a few more launches to make it useful. A tin can is habitable the moment it is on orbit, with one launch.

[Albert VDS]

Let's all think about how awesome this is; a commercially made inflatable module is being launched by a commercially made rocket.

[Nibb31]

It's a given, really. But there are many studies...

When a human is put into a small volume, they can start to get... crazy.

Rubbish. Did Gemini crews go crazy ? Do submarine crew go crazy? Truck drivers? Cubicle workers? Miners? Flight attendants?

Ever wondered why the ISS had 900+ m^3 of volume? So space sickness doesn't happen would be my guess.

Nothing to do with space sickness. The size of the ISS is driven by the mission equipment that needs to be on board.

There are detrimental effects to large volumes. See Skylab. One of the lessons was that astronauts routinely go stuck in the middle of the volume with nothing to grab on to. ISS modules are designed so that astronauts are always in arm's reach of a wall or a handle of some sort.

Likewise, inflatable modules will never be used as large open spaces. They need outfitting with walls and floors.

Expandable just allow us to launch bigger stuff to space with less cost. And it save us design headaches either trying to fit a bigger payload into a fairing, or having to split that payload to multiple smaller payload and dealing with assembling them together.

Instead, someone has to inflate the module and then spend quite some time outfitting the interior with everything that couldn't fit inside when the module was deflated. In order to be used, an inflatable shell needs internal walls, floors, wiring, ventilation, and then furniture and equipment. This can represent a lot of expensive on-orbit work and some logisitics flights for the interior equipment. This isn't necessarily cheaper than launching an equal-size volume in two hardshell modules.

Let's all think about how awesome this is; a commercially made inflatable module is being launched by a commercially made rocket.

All paid for by your taxes. You're welcome. I don't see whats so new about the government paying contractors to do stuff.

[PB666]

Essentially everything ​we don't do is because its not funded

Crowd sourcing,

Just till everyone you need money to make a gigantic beach-ball, they will fall for it, paint it pretty colors and tell everyone they need a telescope to see it.

[Kryten]

Let's all think about how awesome this is; a commercially made inflatable module is being launched by a commercially made rocket.

Just like every USOS module.

[Albert VDS]

All paid for by your taxes. You're welcome. I don't see whats so new about the government paying contractors to do stuff.

I don't think so.

Just like every USOS module.

But these companies are trying to open new markets.

Edited March 15, 2015 by Albert VDS

[Kerbart]

Rubbish. Did Gemini crews go crazy ? Do submarine crew go crazy? Truck drivers? Cubicle workers? Miners? Flight attendants?

I'd like to see some quotes on truckers, cubicle workers and flight attendants who spent months after another in their confined workspace without ever leaving. The issue is not "being in a small space raises stress levels". The issue is "being in a small space without ever getting out" which raises stress to unhealthy levels. Of course crew is pretty much selected on being highly resistant to this, but anything that can be done to lower stress levels is welcome.

Miners get out every day. If they get locked in because of, ehm, logistical problems at the mine, they tend to have pretty severe mental health issues after recovery.

Old fashioned submarines mainly sailed at the surface with the hatches open whenever the chance was there. Modern submarines (even Diesel ones), while cramped for the most of us, are fairly spacious, especially compared to ISS quarters.

Nothing to do with space sickness. The size of the ISS is driven by the mission equipment that needs to be on board.

There are detrimental effects to large volumes. See Skylab. One of the lessons was that astronauts routinely go stuck in the middle of the volume with nothing to grab on to. ISS modules are designed so that astronauts are always in arm's reach of a wall or a handle of some sort.

Likewise, inflatable modules will never be used as large open spaces. They need outfitting with walls and floors.

Instead, someone has to inflate the module and then spend quite some time outfitting the interior with everything that couldn't fit inside when the module was deflated. In order to be used, an inflatable shell needs internal walls, floors, wiring, ventilation, and then furniture and equipment. This can represent a lot of expensive on-orbit work and some logisitics flights for the interior equipment. This isn't necessarily cheaper than launching an equal-size volume in two hardshell modules.

All paid for by your taxes. You're welcome. I don't see whats so new about the government paying contractors to do stuff.

[Albert VDS]

You can't really compare Gemini with a submarine, let alone a cubicle.

The most obvious reason is the fact that they could only "sit".

[RainDreamer]

I think it has potential, especially for equipments that are too big to be launch at once while assembled, but can be disassembled and launched along with the module on a seperate smaller cargo module in the same payload, or they perhaps could work as simple storage as well. But it is not going to be anything miraculous, no one module to rule them all. Just something nifty we can have right now to allow more flexibility in design.

[hugix]

What I meant was, once you put it up there you can't launch astronauts up to live in it. It has no consumables, no furnishings, nothing to do, no beds (like those sleeping compartments). It takes a few more launches to make it useful. A tin can is habitable the moment it is on orbit, with one launch.

you can launch the interior to on the same launch. Just pack it tight and let the astronauts unpack it once in orbit.

[Ralathon]

Twice the ISP equals twice the Dv. Beyond the Ln part, it's all basic math.

Sorry to go off on a tangent here. But nuclear thermal rockets only hit high ISP values because their exhaust gasses are so light. It is true that you get roughly 1k ISP when you use liquid hydrogen, but this comes at a price. Reaction mass like Liquid hydrogen and ammonia are so ridiculously low density that you need very large tanks to get good dV. Very large tanks means a lot of added structural mass and insulation mass. This means that the increase in dV from switching to nuclear thermal is much less than you'd expect. ISP goes up, but mass fraction goes down.

Try it out in KSP for yourself. If you install the Realfuels mod you'll notice that the NERVA is not nearly as OP as it is in stock. It is only better in some limited situations, and then only marginally.

[Nibb31]

I don't think so.

"On December 20, 2012, NASA awarded Bigelow Aerospace a US$17.8 million contract to construct the Bigelow Expandable Activity Module, under NASA's Advanced Exploration Systems (AES) Program."

http://www.nasa.gov/mission_pages/station/news/beam_feature.html

But these companies are trying to open new markets.

There are no new markets. There is government-sponsored research to develop new technology that might or might not be used for commercial purposes. In the end, commercial space only exists because the government is paying for it.

Edited March 15, 2015 by Nibb31

[Bill Phil]

What I meant was, once you put it up there you can't launch astronauts up to live in it. It has no consumables, no furnishings, nothing to do, no beds (like those sleeping compartments). It takes a few more launches to make it useful. A tin can is habitable the moment it is on orbit, with one launch.

Yes you can.

An Expandable module typically has a core. This core houses things like the equipment to inflate it. And you can also pack it with consumables, storage, and even alcoves for sleeping.

[Nibb31]

Old fashioned submarines mainly sailed at the surface with the hatches open whenever the chance was there. Modern submarines (even Diesel ones), while cramped for the most of us, are fairly spacious, especially compared to ISS quarters.

But modern submariners stay for months at sea without surfacing. They don't go crazy.

I can understand that having extra space is a nice comfort, but it's not mission-critical in any way.