Author Topic: Are inflatable modules even necessary for private space stations?  (Read 33988 times)

Offline Darkseraph

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Inflatable modules are a very interesting technology that will have to work all the kinks out before being fully deployed (none of that is pun intended!) It's a neat and cool idea!


But I am wondering, if there is a business case for private space stations, why these would be necessary? There is tons of experience across several corporations over the world in building monolithic metal modules, but very little experience with inflatable space stations. The pressurized volumes possible with a station in the 14 to 22 ton range are actually massive, and because of zero G, much more of that space is available for human habitation than would be the case on earth. Crucially, the really heavy and expensive parts of such space station can't be made lighter by making them inflatable. Things like engines, avionics, sensors, toxic fuel tanks, life support systems. I'm unaware of the evidence that volume constraints are even that big of a problem with current space station, though I think mass is a problem.


Considering all that, if there was a case for a private space station, why not just contract someone like Boeing, EADS Astrium, Mitsubishi or indeed one of the Russian aerospace firms to just make such a monolithic station and launch it on a Ariane V/Proton? I highly doubt this is beyond their technical capabilities.

 :o
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Offline M_Puckett

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Necessary?  No.

Desirable?  Yes.

The BA 330 has about the same interior space as Skylab, a station that required a Saturn V to launch and yet itself weighs like a third the weight of Skylab.

3 times the volume for a given lift is nothing to sneeze at.
« Last Edit: 03/15/2015 12:47 am by M_Puckett »

Offline A_M_Swallow

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{snip}
Considering all that, if there was a case for a private space station, why not just contract someone like Boeing, EADS Astrium, Mitsubishi or indeed one of the Russian aerospace firms to just make such a monolithic station and launch it on a Ariane V/Proton? I highly doubt this is beyond their technical capabilities.


It may be technical possible for a private spacestation with solid walls but no one with sufficient money has placed such a contract.

Offline Dalhousie

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Necessary?  No.

Desirable?  Yes.

The BA 330 has about the same interior space as Skylab, a station that required a Saturn V to launch and yet itself weighs like a third the weight of Skylab.

3 times the volume for a given lift is nothing to sneeze at.

I don't believe the claims about the BA330 mass.  Most of the mass of a spacecraft comes from the equipment, not the pressure hull.  If BA330 is only a third of the mass of Skylab, that is because it is only a shell. 
Apologies in advance for any lack of civility - it's unintended

Offline M_Puckett

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The SIVB the Skylab was derived from had to be structurally strong enough to support the LM, SM and the CM stacked on top thru Max Q too.  It was over-built for a purpose built station.

Offline Darkseraph

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Why is it all that desirable to the point you'd wait until the tech came along to do such a station?

I know they create lots of pressurized volume for the initial mass..but I see no evidence volume is actually a huge constraint with current space stations, that mass of equipment, fuel and resupply is a much bigger constraint. 90 cubic metres is a huge space. That was about the size pressurized volume of Salyut. Other ISS modules are about the same. 3 or 4 people in such a space, with their experiments wouldn't be overcrowded. :/

We don't know the real costs of the station Bigelow is proposing, but i don't understand why it would be all that much cheaper than a metal hulled version. Certainly the purpose of space stations is not to create as much volume as possible just because bigger numbers sound cool...
"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." R.P.Feynman

Offline Nilof

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No, it is to create as much volume as possible because people are going to live in that volume for months, especially if the module is intended to be an option for deep space missions.

For launching space station modules, most launchers are fairing limited, not mass limited. The non-expanded BA-330 can just barely fit inside the standard fairing of the Falcon Heavy, even though it is only half of the maximum payload mass-wise. If you're going to send up anything with a decent volume in a single launch on a reasonably cheap rocket, inflatable modules are very nice to have.
« Last Edit: 03/25/2015 08:46 am by Nilof »
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline mheney

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Plus, you want to test technologies and approaches to doing things.  Flying an inflatable module to ISS allows one to evaluate inflatable module technology - and technology evaluations do fall under ISS's mission as a laboratory ...

Offline Darkseraph

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The proposed business model for private space stations proposed by Bigelow is that people will rent them out for weeks at time, not the months even year of the ISS. They're not even deep space missions. In fact, mission to Tiangong 1 were carried out for periods of two weeks, with it's pressurized volume being only 15m3...90-100 cubic meters is gigantic by comparison.

Sure inflatable space stations would be nice to have..

My own thinking about it is that it doesn't really matter too much if private stations are hard hulled or inflatable, that the biggest problems are the lack of transport and the fact the biggest potential customer already owns a gigantic space station. SpaceX, if it were so inclined probably could apply it's experience of making rockets and capsules into a private station it could launch on Falcon Heavy and resupply with it's two vehicles. Low Earth orbit might be a place they test out human-systems for going to Mars, but get other customers to help pay for it. I in fact wouldn't rule that out after the satellite constellation announcement, though I doubt it.



"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." R.P.Feynman

Offline Burninate

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The proposed business model for private space stations proposed by Bigelow is that people will rent them out for weeks at time, not the months even year of the ISS. They're not even deep space missions. In fact, mission to Tiangong 1 were carried out for periods of two weeks, with it's pressurized volume being only 15m3...90-100 cubic meters is gigantic by comparison.

Sure inflatable space stations would be nice to have..

My own thinking about it is that it doesn't really matter too much if private stations are hard hulled or inflatable, that the biggest problems are the lack of transport and the fact the biggest potential customer already owns a gigantic space station. SpaceX, if it were so inclined probably could apply it's experience of making rockets and capsules into a private station it could launch on Falcon Heavy and resupply with it's two vehicles. Low Earth orbit might be a place they test out human-systems for going to Mars, but get other customers to help pay for it. I in fact wouldn't rule that out after the satellite constellation announcement, though I doubt it.

Inflatable modules are a remarkably superior way of producing a microgravity space station or transit habitat, to aluminum can modules, because of impact resistance and because of fairing diameter and (to a lesser extent) because of launch mass.  Probably also because of money too, but that has not been demonstrated.

They are a very good way to scale up to larger numbers of people, and a moderately good way to launch missions cheaper than the ISS.

No, they do not solve the fundamental problem at present with microgravity space stations & transit habitats, that of a market for sending lots of people into space every year in a steady growth-market for human spaceflight.  This is a greater issue than any of the problems inflatable modules solve: Solve this problem and even aluminum cans would be workable.
« Last Edit: 03/15/2015 09:07 pm by Burninate »

Offline AS_501

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Once launched, isn't an inflatable space station essentially a house with no furnishings?  Is the business model affected by the time and cost of installing life support systems, decks, sleeping quarters, lab equipment, etc.?  It reminds me of the original Skylab "Wet Workshop" concept, where considerable time was required for installation of decks, sleeping quarters, etc. after the last residual propellant was expelled.  I'm not familiar with how much such work will be required for a Bigelow module or the like, but my sense is the more outfitting you can get done on the ground, the better.  That was the beauty of Skylab.
Launches attended:  Apollo 11, ASTP (@KSC, not Baikonur!), STS-41G, STS-125, EFT-1, Starlink G4-24, Artemis 1
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Offline Darkseraph

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That was my thinking about it as well, it really just solves a problem of making a wider hull with more volume on an EELV sized vehicle..but I am not sure that is even a huge problem at present (4 - 5 metres wide by about 12 metres long is a far larger space than people imagine!) You still have to outfit this station with equipment that can't be preinstalled and requires some ikea effort in space with the crew. I am not sure how they use the walls, but i am sure it requires assembly if they're usable in a conventional way at all. 


I am not even talking about the problem of launching many people every year to a space. I am more thinking of something about the size of Salyut that carries 3 or 4 people at a time for stays measured in weeks. Nothing space cadet like with rotating wheels and in orbit decontamination bays.


EDIT: The one place I am very much convinced inflatables are remarkably better are for heat shields used in entry descent and landing, esp on Mars. A habitable volume for up to six people could be launched on EELVs, but not even a 12 meter monster rocket could handle some of the heat shields that would be needed for landing; say 40 tons of equipment on Mars.


« Last Edit: 03/15/2015 10:58 pm by Darkseraph »
"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." R.P.Feynman

Offline TrevorMonty


Don't' confuse the BEAM which is just an empty shell with BA330 which is a fully assembled space station, only needing inflation and deployment of solar panels once in space.

Offline Paul451

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I am not sure how they use the walls, but i am sure it requires assembly if they're usable in a conventional way at all.

With an inflatable, you need to reverse your image of how its used. Aluminium modules have a narrow corridor down the centre of the module and rackspace and ECLSS on the walls. Inflatables are have a hard core of prefitted rackspace and ECLSS, with the habitable volume all around it. No assembly required.

The walls can additionally be used to attach storage, sleeping quarters, and other bulk items, but don't need an extra hard-frame around the walls before you can use them. That's not how inflatables work.

They're not even deep space missions.

Bigelow is interested in using them as BEO modules, including lunar bases. Specifically because inflatables are better suited for such missions than aluminium cans.

Inflatable modules are a very interesting technology that will have to work all the kinks out before being fully deployed
[...]
There is tons of experience across several corporations over the world in building monolithic metal modules, but very little experience with inflatable space stations.
[...]
Why is it all that desirable to the point you'd wait until the tech came along to do such a station?

Experience isn't something you can keep in an archive, you have to constantly work it on new projects. The last space station module made in the US was over a decade ago. (And launched nearly a decade ago.) Whatever architecture you choose, you are creating a team from scratch and developing new technology. Bigelow at least has their team in place.

[For example, Boeing used Bigelow as a subcontractor for the life-support systems for CST-100 capsule, even though Boeing built most of the US modules on ISS. Experience isn't storable.]

The novel part of Bigelow's inflatables (the skin and the deployment) is already tested in space with the two Genesis modules. The untested parts are the berthing connection (will be tested with BEAM), the ECLSS, and rackspace, which all attach to the hard core of the module and are thus much more conventional. In other words, the effort to develop those systems is exactly the same as required for an aluminium can.

Offline Norm Hartnett

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Once launched, isn't an inflatable space station essentially a house with no furnishings? <snip>

Not exactly. BEAM is, more or less, designed that way by NASA specifications and Dragon unpressurized cargo capacity. However the two Genesis spacecraft had communication, power, and attitude control systems as well as a host of other 'furnishings'. The BA330's are expected to have quite a bit more furniture on board at launch.

Edit: Inflatables may also be more resilient to MOD strikes and provide a safer radiation environment compared to tin cans. I suspect that BEAM will be a test case for this.
« Last Edit: 03/30/2015 03:56 pm by Norm Hartnett »
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Online spacenut

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Isn't the 330 module 18" thick with layers of Kevlar and Aluminum skin and plastic.  On ISS they even went outside on spacewalks and installed Kevlar covers for micro meteorite protection, so the 330 already has Kevlar built in. 

Offline Dalhousie

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Are inflatable modules necessary?  No they are not.  Are they useful?  Maybe, although I am yet to be convinced.
Apologies in advance for any lack of civility - it's unintended

Offline Norm Hartnett

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Actually not Kevlar but rather Vectran which NASA has lots of experience with. Spacesuits (EMU)among other things. So far as I have been able to discover there is no aluminum in the BA skins. In fact the lack of aluminum is one of the advantages since there is no secondary radiation generated thus reducing overall radiation exposure.
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Offline Kansan52

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The Bigelow modules are tougher than aluminum cans as people have posted.

They will not want the BA 300's fully outfitted as the occupants will bring their experiments. The racks will be based on current ISS racks.

And the ISS modules were not fully equipped but, if memory serves, it was mass limitations.

Also, like it has been posted, BA 300 is designed plus, as I understand it, being constructed. Any ISS type module hasn't bent metal yet. Time is money.

Of course, once Bigelow has blazed the trail, the could be both in ten years.

Offline Dalhousie

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The Bigelow modules are tougher than aluminum cans as people have posted.

Since "alunimium cans" have hardly proved fragile in space flight and how well the Genesis modules have stood up to spacelfight is not public knowledge AFAIK, I would see this as an unsubstantiated claim by the advocates.


Quote
They will not want the BA 300's fully outfitted as the occupants will bring their experiments. The racks will be based on current ISS racks.

Which meands that all claims about the supposed mass advantages on inflatbale structures are specious.

Quote
And the ISS modules were not fully equipped but, if memory serves, it was mass limitations.

Some were, some weren't.  But I find it strange how fitting something out in space is a parsed as an advanatage for inflatables and a fault for rigid structures

Quote
Also, like it has been posted, BA 300 is designed plus, as I understand it, being constructed. Any ISS type module hasn't bent metal yet. Time is money.

Is BA330 being built?  There are lots of mockups.

Apologies in advance for any lack of civility - it's unintended

Offline Dalhousie

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No, it is to create as much volume as possible because people are going to live in that volume for months, especially if the module is intended to be an option for deep space missions.

For launching space station modules, most launchers are fairing limited, not mass limited. The non-expanded BA-330 can just barely fit inside the standard fairing of the Falcon Heavy, even though it is only half of the maximum payload mass-wise. If you're going to send up anything with a decent volume in a single launch on a reasonably cheap rocket, inflatable modules are very nice to have.

You don't need as much volume as possible, you need enough volume, which is about 20m3 per person free volume.  Current space station modules are not volume limited, but mass limited.
Apologies in advance for any lack of civility - it's unintended

Offline Dalhousie

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Actually not Kevlar but rather Vectran which NASA has lots of experience with. Spacesuits (EMU)among other things. So far as I have been able to discover there is no aluminum in the BA skins. In fact the lack of aluminum is one of the advantages since there is no secondary radiation generated thus reducing overall radiation exposure.

The secondary radiation issue is, I suspect over stated as all materials will generate some secondary radiation and even an inflatable willcontain a substantial amount of structural and system aluminium.  Besides, aluminium is used for radiation shielding, so is hardly a viability.
Apologies in advance for any lack of civility - it's unintended

Offline WindnWar

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The Bigelow modules are tougher than aluminum cans as people have posted.

Since "alunimium cans" have hardly proved fragile in space flight and how well the Genesis modules have stood up to spacelfight is not public knowledge AFAIK, I would see this as an unsubstantiated claim by the advocates.


Quote
They will not want the BA 300's fully outfitted as the occupants will bring their experiments. The racks will be based on current ISS racks.

Which meands that all claims about the supposed mass advantages on inflatbale structures are specious.

Quote
And the ISS modules were not fully equipped but, if memory serves, it was mass limitations.

Some were, some weren't.  But I find it strange how fitting something out in space is a parsed as an advanatage for inflatables and a fault for rigid structures

Quote
Also, like it has been posted, BA 300 is designed plus, as I understand it, being constructed. Any ISS type module hasn't bent metal yet. Time is money.

Is BA330 being built?  There are lots of mockups.

You seem to disregard any info that validates the inflatable design for a preconceived notion that its a fad or won't succeed. We know the Genesys modules are still on orbit, and have been for years now. I would assume NASA has far greater insight into them as part of the BEAM module as it was probably used to validate it before launch. They are mass efficient, space efficient and from the models, should be more resistant to mmd strikes and radiation, all of which the BEAM module will help validate. No one is rushing into this, and since the only country currently building any station modules currently besides Bigelow is China, it is currently the only company keeping skills in place for modules. None of these are really debatable.

We will know in a couple years a lot more info on how BEAM fairs and that will likely drive the direction things are headed. But just because it seems odd, that's a rather strange reason to simply disregard all the info that has been presented to you.

Offline Norm Hartnett

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Actually not Kevlar but rather Vectran which NASA has lots of experience with. Spacesuits (EMU)among other things. So far as I have been able to discover there is no aluminum in the BA skins. In fact the lack of aluminum is one of the advantages since there is no secondary radiation generated thus reducing overall radiation exposure.

The secondary radiation issue is, I suspect over stated as all materials will generate some secondary radiation and even an inflatable willcontain a substantial amount of structural and system aluminium.  Besides, aluminium is used for radiation shielding, so is hardly a viability.

Most of your objections to inflatables require more research but the radiation question is rather easy to examine. Lets conduct a little thought experiment;

If we have two modules that are exactly equal in size and contain exactly same racks/wiring/experiments/etc one constructed with an aluminum skin and one with a BA skin the one with the aluminum skin would always be the more dangerous as it would always produce more secondary radiation.

Aluminium is only used for radiation shielding by NASA by default due to weight. Most sources I've been able to find agree that aluminium is a terrible shielding material, especially for X-rays, Gamma Rays, Solar Energetic Particles, Solar Particle Events, and Galactic Cosmic Rays. Our astronauts already have limited lifetimes in LEO and the situation only gets worse the further from Earth we get.

Are inflatables necessary for private space stations? No.

Are they safer and cheaper? Quite possibly, that's what we're trying to find out.
“You can’t take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware.” Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Offline JasonAW3

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The Bigelow modules are tougher than aluminum cans as people have posted.

Since "alunimium cans" have hardly proved fragile in space flight and how well the Genesis modules have stood up to spacelfight is not public knowledge AFAIK, I would see this as an unsubstantiated claim by the advocates.

There are numerous Nasa videos that seem to indicate otherwise.  There are tests that have been done that have indicated that a hit from even a pebble sized meteor could cause substantile damage to the ISS, versus the Bigelow module which gives and deforms much like bullet resistant body armor does.  Currently, Nasa is using, what in effect is, Spaced Armor to mitigate debris damage.  While this has proven effective in the past, even they admit that it's not perfect.  Neither is the Bigelow Module either, but it can take a more sizable impact than could the ISS before potentile pressure failure.

Quote
Quote
They will not want the BA 300's fully outfitted as the occupants will bring their experiments. The racks will be based on current ISS racks.

Which meands that all claims about the supposed mass advantages on inflatbale structures are specious.


Comparing Apples to Apples, the same volume for the BA330 is far lower in mass than a comparable volume of current ISS modules.

Quote
Quote
And the ISS modules were not fully equipped but, if memory serves, it was mass limitations.

Some were, some weren't.  But I find it strange how fitting something out in space is a parsed as an advanatage for inflatables and a fault for rigid structures

Quote
Also, like it has been posted, BA 300 is designed plus, as I understand it, being constructed. Any ISS type module hasn't bent metal yet. Time is money.

Is BA330 being built?  There are lots of mockups.

Actually, as I understand it, yes, two modules have been currently constructed and one is being used for destructive testing.  Pushing the design boundries until they break.
« Last Edit: 04/01/2015 05:38 pm by JasonAW3 »
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Offline Dalhousie

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The Bigelow modules are tougher than aluminum cans as people have posted.

Since "alunimium cans" have hardly proved fragile in space flight and how well the Genesis modules have stood up to spacelfight is not public knowledge AFAIK, I would see this as an unsubstantiated claim by the advocates.

There are numerous Nasa videos that seem to indicate otherwise.  There are tests that have been done that have indicated that a hit from even a pebble sized meteor could cause substantile damage to the ISS, versus the Bigelow module which gives and deforms much like bullet resistant body armor does.  Currently, Nasa is using, what in effect is, Spaced Armor to mitigate debris damage.  While this has proven effective in the past, even they admit that it's not perfect.  Neither is the Bigelow Module either, but it can take a more sizable impact than could the ISS before potentile pressure failure.

A pebble sized meteor is huge.  A very much doubt a Bigelow inflatable will survive that either.  remember two that a Bigelow module still has a lot of external equipment such as antennae, solar panels and radiators which will be just as vulnerable as a those of conventional station.

Quote
Quote
Is BA330 being built?  There are lots of mockups.

Actually, as I understand it, yes, two modules have been currently constructed and one is being used for destructive testing.  Pushing the design boundries until they break.

Thank you.
Apologies in advance for any lack of civility - it's unintended

Offline Burninate

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The Bigelow modules are tougher than aluminum cans as people have posted.

Since "alunimium cans" have hardly proved fragile in space flight and how well the Genesis modules have stood up to spacelfight is not public knowledge AFAIK, I would see this as an unsubstantiated claim by the advocates.

There are numerous Nasa videos that seem to indicate otherwise.  There are tests that have been done that have indicated that a hit from even a pebble sized meteor could cause substantile damage to the ISS, versus the Bigelow module which gives and deforms much like bullet resistant body armor does.  Currently, Nasa is using, what in effect is, Spaced Armor to mitigate debris damage.  While this has proven effective in the past, even they admit that it's not perfect.  Neither is the Bigelow Module either, but it can take a more sizable impact than could the ISS before potentile pressure failure.

A pebble sized meteor is huge.  A very much doubt a Bigelow inflatable will survive that either.  remember two that a Bigelow module still has a lot of external equipment such as antennae, solar panels and radiators which will be just as vulnerable as a those of conventional station.


Online jongoff

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My take is somewhat similar to Dalhousie's original response--Inflatables aren't necessary for commercial space stations, and the jury is still out on whether they really are superior. I think the main reason so many people seem to think they are is that the only private space station company that has had serious money was Bigelow, and inflatables was the approach they took. But really, I think there are plenty of advantages to using normal aluminum in a LEO application, especially if you build the module integral with the Payload Fairing OML (maybe with some MMOD-MLI on the outside). You can't get quite the same volume, as you can with a max case inflatable, but your structure is likely lighter, and might be easier to pre-integrate. I did a blog post on the topic a few months ago: http://selenianboondocks.com/2014/10/integral-payload-fairing-habitats/

But as I said, the jury is probably still out--inflatables might be better in some cases, all cases, or almost no cases. Not enough experience to really tell at this point.

But I do think that automatically assuming that commercial space stations means Bigelow is premature. I hope they're successful, but I also hope someone else finds a way to compete with them. I'm no fan of monocultures.

~Jon

Offline Norm Hartnett

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After some thought I realized that the answer to your original question “Are inflatable modules even necessary for private space stations?” is, self-evidently, yes.

Why? Because no other private party is attempting to create a space station of any kind. No other private party has spent significant money nor have they orbited one, let alone two, test space craft. No private party has talked NASA into testing a prototype on the ISS.

Why? Economics and vision. (I believe.)

Inflatable modules are necessary for private space stations because no one else is building any other sort of private space station.

“if there is a business case for private space stations, why these would be necessary?”

Because Bigelow Aerospace is the only one building private space stations and inflatables are what they believe will work. Presumably they know what they're doing.

I suspect that's not the answer you were looking for but it is the reality.

BEAM probably isn't necessary to BA's business plan but it certainly can't hurt and may provide a kick start to investment and customer orders.

Edit: I see Jon reached a similar conclusion about the same time I did.
« Last Edit: 04/02/2015 03:17 am by Norm Hartnett »
“You can’t take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware.” Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Online jongoff

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After some thought I realized that the answer to your original question “Are inflatable modules even necessary for private space stations?” is, self-evidently, yes.

Why? Because no other private party is attempting to create a space station of any kind. No other private party has spent significant money nor have they orbited one, let alone two, test space craft. No private party has talked NASA into testing a prototype on the ISS.

Why? Economics and vision. (I believe.)

Inflatable modules are necessary for private space stations because no one else is building any other sort of private space station.

“if there is a business case for private space stations, why these would be necessary?”

Because Bigelow Aerospace is the only one building private space stations and inflatables are what they believe will work. Presumably they know what they're doing.

I suspect that's not the answer you were looking for but it is the reality.

BEAM probably isn't necessary to BA's business plan but it certainly can't hurt and may provide a kick start to investment and customer orders.

I guess I'd find this line of reasoning more compelling if I thought Bigelow Aerospace's odds of succeeding were higher. They're definitely the only ones publicly working the problem, but that's no guarantee of success. Once again, I hope they're successful, but I've been hoping that for over a decade and a half. Personally, I wouldn't be surprised if some other party beat them to market at this point. Hopefully BEAM can turn things around for them as a company.

~Jon

Offline Norm Hartnett

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Yes BA really does need an Angel, someone to come along and buy a BA330 and loft it along with the manned flights and a utilization plan. However, until there are commercial manned flights there really isn't a market so it's unlikely there will be competitors.
“You can’t take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware.” Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Offline Oli

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I am sceptical as well. An inflatible station means the entire hull must be flexible/expandle. I suspect that severly limits you  in the materials you can use and in the overall design. A non-inflatible station needs a rigid hull but you can fit it with whatever protection etc. you like.

So other than volume and potentially mass I only see disadvantages.

Btw, why not use composites for the hull instead of aluminium?
« Last Edit: 04/02/2015 06:08 am by Oli »

Offline cosmicvoid

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Because Bigelow Aerospace is the only one building private space stations and inflatables are what they believe will work. Presumably they know what they're doing.

One would hope they know what they're doing, but comments by BA ex-employees make me skeptical.  I'm not anti-BA; I hope they succeed.

I am sceptical as well. An inflatible station means the entire hull must be flexible/expandle. I suspect that severly limits you  in the materials you can use and in the overall design. A non-inflatible station needs a rigid hull but you can fit it with whatever protection etc. you like.

The rigidity of the inflatable is in the core/spine, which is not flexible.  The solid hull needs added protection, so I don't see its advantage.

Quote
Btw, why not use composites for the hull instead of aluminium?

I'll take a guess here that composites are too brittle, and difficult to repair. And probably very expensive.
Infiinity or bust.

Offline Oli

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The solid hull needs added protection, so I don't see its advantage.

Yes, but an inflatable might as well. If I understand correctly the Kevlar (or Kevlar-like) fabric in inflatables basically doubles as "structure" (in the sense that it keeps the entire thing from exploding), while on ISS modules for example it must be added as protection. However, ISS modules also have bumpers (aluminum sheets) placed at a standoff which causes incoming particles to disintegrate before they hit the inner wall. For deep space additional radiation shielding would be necessary, for example plastics, water tanks etc. The question is whether such additional protection could easily be designed to be flexible (as a fabric) such that it is expandable and if yes, how much more costly it would be.

I'll take a guess here that composites are too brittle, and difficult to repair. And probably very expensive.

They could be too brittle in the event of an impact. I do not agree on cost though, composite pressure tanks from what I know are cheaper than metal ones.

Offline Paul451

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For deep space additional radiation shielding would be necessary, for example plastics, water tanks etc. The question is whether such additional protection could easily be designed to be flexible (as a fabric) such that it is expandable and if yes, how much more costly it would be.

You're not sure if plastic and water can be flexible?  :o
 
But in general, you seem to be assuming that radiation and micrometeorite protection haven't been developed for inflatables yet. Bigelow's inflatables are made from the sort of materials that are already used to protect space suits and which have been added to ISS modules. They have been tested on Earth and in space.

ISS modules also have bumpers (aluminum sheets) placed at a standoff which causes incoming particles to disintegrate before they hit the inner wall.

Whipple shields. However, there are downsides. 1: The shield destroys itself when it is hit. You need to replace any section of shield that has been hit. I believe the practice now is to protect the Whipple shield with an external panel of multi-layer fabric shielding (Kevlar/Nextel/etc) which don't have to be replaced after every impact, leaving the Whipple shield as the last resort. (By protecting the Whipple from smaller impacts, you preserve its function for major impacts, while reducing maintenance.)

2: Whipple shields are fairly light, but the necessary gaps means they are bulky, they eat into your volume. Multi-layer fabric shielding is not quite as bulky, but importantly, in inflatable modules, you make up the volume by removing empty internal volume of the module during launch.

3: Whipple shields create radioactive particle showers when hit by high energy particles, effectively multiplying the radiation load on the astronauts. I believe the external fabric layers on ISS were intended to reduce this effect too.

Offline Paul451

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I'll take a guess here that composites are too brittle, and difficult to repair. And probably very expensive.
They could be too brittle in the event of an impact. I do not agree on cost though, composite pressure tanks from what I know are cheaper than metal ones.

They would be more expensive once designed to survive in space. Ie, once designed not to be brittle, not to degrade in a vacuum or monoatomic oxygen, or direct sunlight or sharp thermal cycling, etc.

Offline TrevorMonty

Bigelow plans to add radiation shielding by Velcro bladders of water attached to inside of wall. Given its large internal diameter, layering these shielding bladders shouldn't be an issue. As technology improves the shielding bladders can be changed for something better.

Offline Burninate

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Bigelow plans to add radiation shielding by Velcro bladders of water attached to inside of wall. Given its large internal diameter, layering these shielding bladders shouldn't be an issue. As technology improves the shielding bladders can be changed for something better.
Whole-hab shielding of this sort gets extraordinarily mass-intensive very quickly.  Water (and food, and equipment, and everything else) that has to be on the hab anyway, can of course be mounted on the walls for free.

We use these pools for short-term storage because water is a really good radiation shield. How good? Well, according to a report on the topic prepared for the DoE back in 1977, a layer of water 7 centimeters thick reduces the ionizing radiation (rays and particles) transmitted through it by half (the remainder is captured or moderated to non-ionizing energy levels, mainly heat).

A BA-330 has something on the order of 260m^3 of interior surface area.  7cm of water over the whole of the habitat is 70kg/m^2, bringing the total mass cost to 18.2 tons for a 50% reduction in solar radiation.

So effectively, to halve the radiation load you need to ~double habitat mass.  To reduce it by 75%, you need to ~triple habitat mass.  To reduce it by 95%, a 20 ton BA-330 becomes a 98 ton BA-302, accounting for the reduced volume: One ton of water for every four cubic meters.

The math isn't so extreme on larger habitats.  A BA-9000 has only about ten times as much surface area as a BA-330, and a 95% radiation reduction there can be accomplished with around 800 tons, or one ton of water for every 11 cubic meters.

In my opinion, for any habitat that has to move around, creative mounting of the chemical or nuclear-thermal propellant tanks, and thermal countermeasures to permit that, using semi-cryogenic fuel, will probably be the first really effective whole-hab radiation shielding.  Short of that, I think we'll see "safe rooms" established out of the existing interior water supply, where the crew will retreat only during solar radiation storms.  Packing the crew into a refrigerator-sized safe room for a few hours per mission doesn't cost much, design-wise, and doesn't pose extraordinary psychological issues for the crew in such a limited capacity.
« Last Edit: 04/03/2015 03:08 pm by Burninate »

Offline baldusi

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Plypropylene has a similar capability wrt radiation as water. You could layer it on the outside of an aluminum can and get the same effects. So, it's not like it's such a huge advantage.
The main issue I see for inflatable is outfitting. You have to spend a lot of crew time installing equipment and moving things around. And the configuration affects the radiation shielding, too. The ISS and such 4m al cans put all the equipment and ECLSS on the outside, which also acts as radiation barrier. The BA330 inflatable, puts all those things on the core, putting the crew closer to the walls, thus, only the inflatable walls act as radiation shield.
When you look at the SkyLab II trades on interior configuration, you find the same configuration as the BA-2100, i.e. three "floors". The big difference is that in an 8.4m aluminum can, all the equipment and ECLSS is already installed and routed on the comfortable gravity well of Earth's surface, while a BA-2100 would need a lot of ducting and installation. Things as silly as ventilation ducting, with the required power and data would eat a lot of crew time in installation. Is is worth the savings in mass if you have to spend an extra six months on orbit (or even more) doing simple installations?

Offline A_M_Swallow

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{snip}
When you look at the SkyLab II trades on interior configuration, you find the same configuration as the BA-2100, i.e. three "floors". The big difference is that in an 8.4m aluminum can, all the equipment and ECLSS is already installed and routed on the comfortable gravity well of Earth's surface, while a BA-2100 would need a lot of ducting and installation. Things as silly as ventilation ducting, with the required power and data would eat a lot of crew time in installation. Is is worth the savings in mass if you have to spend an extra six months on orbit (or even more) doing simple installations?

An outfitting time of several months definitely pushes towards have a spacestation to assemble the transfer vehicles.

Offline MikeAtkinson

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Inflatable structures are good for large volumes - so crew accommodations, (cabins, exercise area, galley, etc.) and storage.

Hard shells are best for science (access to vacuum, fitting out on Earth, probably better micro-g) , engineering tests (unusual shapes and external fittings), semi-permanent additions and nodes, cupola, etc.

Multi-module stations are likely to have both inflatable and hard shell modules each doing what they are good at.

Offline Norm Hartnett

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While not strictly on topic it dawned on me that a B330 might be a very good place to test "artificial gravity". I envisioned a rotating wheel rim set inside the circumference of the B330. I was unable to find a internal diameter for the B330 but the exterior diameter is 6.7 m so I guesstimated about 5 m. It has been several decades since I've done any physics or math (other than darts) so my results are questionable (very).

Known

 Radius (internal diameter of B330/2) ~ 2.5 m

  Circumference = 15.708 m

 Acceleration ("gravity") Earth E = 9.807 m/s^2, Mars M = 3.711 m/s^2, Moon L = 1.622 m/s^2

Unknown;

  RPM

centrip accel a = v^2/r

 v = sqrt[a*r]

rpm = v/c

 vE = sqrt [9.807*2.5] = 4.951

 vM = sqrt [3.711*2.5] = 3.046

 vL = sqrt [1.622*2.5] = 2.014

rpmE = 4.951/15.808 = 0.313 rpm

rpmM = 3.046/15.808 = 0.193 rpm

rpmL = 2.014/15.808 = 0.127 rpm

These rates seem low but, if correct, it would seem that habitats for mice could be constructed within a B330 relatively easily. We have no data on extended stays (months to years) in low gravity for Earth lifeforms and this might be a very interesting experiment.

I wondered about spinning up the habitats and causing the B330 to counter rotate but then I realized that , conveniently enough, if the Moon and Mars habitats counter rotate to the Earth habitat they would cancel each other to some degree.
“You can’t take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware.” Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Offline nadreck

Aluminum "cans" and Bigellow style modules are not the only options.  In fact for stations built in micro gravity, eventually, robotic assembly using discreet panels, supports, layers built up are all possible.  It is a given that working in a vacuum either in microgravity or not, it is far to difficult and time consuming for humans to assemble a building in pieces, human work will be limited to relatively unique repair/installation/testing activities. However if we ever build structures that are equivalent to O'Neil style colonies, the sorts of rotating wheel ones depicted in 2001 A Space Odyssey, and countless fiction and non fiction attempts to predict the future of HSF, it will not be done from complete self contained modules, it will be done from more discreet parts, it will eventually be pressurized, maybe part or all of it eventually rotated for AG, and, I even imagine, even rotating some structures could be incomplete and be added to with discreet parts being received and robotic maintenance and assembly units adding them to the structure.

While it would be costly and disruptive, a rotating station could also be stopped for specific construction activities and re-spun. Note that a microgravity station, or section of a station, would be far more disrupted (in terms of the purity of its microgravity) by construction activity.

So no inflatable modules aren't necessary, but I think they are inevitable as a part of the mix, as are aluminum "cans", but the evolution will be away from both of those.
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline baldusi

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SpinCalc is your friend! As you can see on that site, you really need something like 10m of radius (20m diameter) to get somewhere comfortable to simulate even Mars gravity. An inflatable might be the key, but probably not in the balloon configuration, but rather in something like a torus or so.
If you did had a torus with 20.3m of outer diameter, 2m of pressurized space, and 0.3m of wall thickness, you could pack in 400mł with a 70% efficiency. That would fit (tightly) within the 6.5m x 25m fairing that ULA said can do in a Delta IV Heavy. Only issue is that it would have to weight less than 90kg/mł so that the launcher could actually orbit it.
Given that even polypropylene is something like 900kg/mł, I believe that we would be mass limited for anything "big" than volume constrained.

Offline Norm Hartnett

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SpinCalc is your friend! As you can see on that site, you really need something like 10m of radius (20m diameter) to get somewhere comfortable to simulate even Mars gravity. An inflatable might be the key, but probably not in the balloon configuration, but rather in something like a torus or so.
If you did had a torus with 20.3m of outer diameter, 2m of pressurized space, and 0.3m of wall thickness, you could pack in 400mł with a 70% efficiency. That would fit (tightly) within the 6.5m x 25m fairing that ULA said can do in a Delta IV Heavy. Only issue is that it would have to weight less than 90kg/mł so that the launcher could actually orbit it.
Given that even polypropylene is something like 900kg/mł, I believe that we would be mass limited for anything "big" than volume constrained.

As near as I can tell my calculations seem in agreement with SpinCalc. (if centripetal acceleration = tangential acceleration) Their numbers seem to be for human sized tests, mine are intended for something more conservative and inexpensive eg. mice or something of that scale. The "Comfort Scale" should be much smaller for smaller folks, IMO. ;)
“You can’t take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware.” Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Offline Paul451

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rpm = v/c

Revolutions per Second = v/c

Revolutions per Minute = 60 * v/c

Hence:

rpm Earth = 18 rpm
rpm Mars = 11 rpm
rpm Lunar = 8 rpm


Offline A_M_Swallow

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rpm = v/c

Revolutions per Second = v/c

Revolutions per Minute = 60 * v/c

Hence:

rpm Earth = 18 rpm
rpm Mars = 11 rpm
rpm Lunar = 8 rpm



Earth rpm as a bit fast but if the mice do do look out of the window they should be all right at Mars and Lunar rpm.

We already have living quarters for rodents.  It will have to be fitted onto a wheel or torus.
http://www.nasa.gov/mission_pages/station/research/news/rodent_research
« Last Edit: 04/08/2015 05:31 am by A_M_Swallow »

Offline Norm Hartnett

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rpm = v/c

Revolutions per Second = v/c

Revolutions per Minute = 60 * v/c

Hence:

rpm Earth = 18 rpm
rpm Mars = 11 rpm
rpm Lunar = 8 rpm



D'oh! Ah yes. As I remember units frequently tripped me up back in college physics many years ago. Thanks Paul!


Earth rpm as a bit fast but if the mice do do look out of the window they should be all right at Mars and Lunar rpm.

We already have living quarters for rodents.  It will have to be fitted onto a wheel or torus.
http://www.nasa.gov/mission_pages/station/research/news/rodent_research

I was looking for something that would fit inside the B330 which would eliminate a wheel. I considered the possibility of a module but the only thing I could come up with was putting the module on rails running around the interior circumference of the B330. This causes all sorts of problems not the least of which is maintaining the habitat.
« Last Edit: 04/08/2015 01:31 pm by Norm Hartnett »
“You can’t take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware.” Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Offline Norm Hartnett

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 :( No doubt about it, we're gonna need a bigger station!

The only way I can envision using a B330 for artificial gravity research requires a dedicated station. At those rotational rates the interior would be hot, noisy, and dangerous. Mass required would much higher and costs would be very high. It might be worth it since we need to verify that humans can live and work in Mars gravity for any length of time before we send them more than a years travel time from home.

To return, sort of, to topic. It appears that, for at least this research, a inflatable module is not particularly suitable.

“You can’t take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware.” Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Offline dror

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Inflatabilty is not a requirement for any space station.
It's more of an issue than a solution to a critical need.

BA modules may get there first, though, because of past circumstances and hype.

More probably, the first comercial LEO space station will have a big X painted on it's side, and it will be testing key technologies needed for a trip to mars.
Space is hard immensely complex and high risk !

Offline dror

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Inflatabilty is not a requirement for any space station.
It's more of an issue than a solution to a critical need.

BA modules may get there first, though, because of past circumstances and hype.

More probably, the first comercial LEO space station will have a big X painted on it's side, and it will be testing key technologies needed for a trip to mars.

Unsubstantiated !!!
Space is hard immensely complex and high risk !

Offline JasonAW3

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The Bigelow modules are tougher than aluminum cans as people have posted.

Since "alunimium cans" have hardly proved fragile in space flight and how well the Genesis modules have stood up to spacelfight is not public knowledge AFAIK, I would see this as an unsubstantiated claim by the advocates.

There are numerous Nasa videos that seem to indicate otherwise.  There are tests that have been done that have indicated that a hit from even a pebble sized meteor could cause substantile damage to the ISS, versus the Bigelow module which gives and deforms much like bullet resistant body armor does.  Currently, Nasa is using, what in effect is, Spaced Armor to mitigate debris damage.  While this has proven effective in the past, even they admit that it's not perfect.  Neither is the Bigelow Module either, but it can take a more sizable impact than could the ISS before potentile pressure failure.

A pebble sized meteor is huge.  A very much doubt a Bigelow inflatable will survive that either.  remember two that a Bigelow module still has a lot of external equipment such as antennae, solar panels and radiators which will be just as vulnerable as a those of conventional station.


They've already tested up through .50 calibur high velocity impacts on test articles.  Got through a couple of outer layers, came no where near penetrating the full 18 inches of the outer wall.


Quote
Is BA330 being built?  There are lots of mockups.

Quote
Quote
Actually, as I understand it, yes, two modules have been currently constructed and one is being used for destructive testing.  Pushing the design boundries until they break.

Thank you.

You are Welcome!
« Last Edit: 04/08/2015 08:13 pm by JasonAW3 »
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Offline baldusi

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Inflatabilty is not a requirement for any space station.
It's more of an issue than a solution to a critical need.

BA modules may get there first, though, because of past circumstances and hype.

More probably, the first comercial LEO space station will have a big X painted on it's side, and it will be testing key technologies needed for a trip to mars.
Anyone knows the ISS aluminum wall width? I've calculated that if it is more than 1.1cm wide then the fabric construction is lighter per unit of surface.

Offline Burninate

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Inflatabilty is not a requirement for any space station.
It's more of an issue than a solution to a critical need.

BA modules may get there first, though, because of past circumstances and hype.

More probably, the first comercial LEO space station will have a big X painted on it's side, and it will be testing key technologies needed for a trip to mars.
Anyone knows the ISS aluminum wall width? I've calculated that if it is more than 1.1cm wide then the fabric construction is lighter per unit of surface.
"2mm aluminum pressure shell" plus unspecified graphite-epoxy shield thickness
- in figure 10 of http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20060026214.pdf

"The walls are about 10 cm thick and consist of an inner and outer shell of aluminum (density= 2.7 grams per cubic centimeter) about 0.3 cm thick. In between the two walls is polyurethane to improve radiation shielding of the astronauts inside."
- http://spacemath.gsfc.nasa.gov/Modules/8Mod6Prob1.pdf

"The thickness of outer wall is estimated as 1,5 g/cm (2)"
- http://adsabs.harvard.edu/abs/2014cosp...40E3366T

"the bullet's effect on the ATV's 3-millimeter-thick aluminum wall "
- http://spacenews.com/41022atv-shielding-takes-a-bullet-to-show-space-stations-stopping-power/

"The ISS is largely composed of thin-walled aluminum modules, from 1.27 millimeters (0.05 inches) to 7 millimeters (0.27 inches) thick. The air pressure from within exerts the force to keep the walls rigid."
- http://www.21stcentech.com/developed-artificial-gravity-human-space-flights/

« Last Edit: 04/08/2015 09:04 pm by Burninate »

Inflatable modules are not needed for a space station but once the technology is proven will provide more space to allow the crew to work and life.

Offline AS_501

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Is solar array installation and deployment a more complicated proposition on an inflatable space station?  The few Bigelow renderings I've seen show relatively small array surface areas compared to the ISS, and no truss to hold them out from the station.  Of course, the latest array technology may not need as much collecting area as that used by the ISS arrays, which are more than a decade old.  On the other hand, stubby arrays projecting out from directly from the inflatable station wall may suffer some mutual shadowing problems (?).  If I remember correctly, this was a problem for Mir in its final configuration.  Also, rotation for optimum Sun tracking could be more complicated (?)  Input from solar array experts is appreciated.
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Offline JasonAW3

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Inflatabilty is not a requirement for any space station.
It's more of an issue than a solution to a critical need.

BA modules may get there first, though, because of past circumstances and hype.

More probably, the first comercial LEO space station will have a big X painted on it's side, and it will be testing key technologies needed for a trip to mars.
Anyone knows the ISS aluminum wall width? I've calculated that if it is more than 1.1cm wide then the fabric construction is lighter per unit of surface.
"2mm aluminum pressure shell" plus unspecified graphite-epoxy shield thickness
- in figure 10 of http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20060026214.pdf

"The walls are about 10 cm thick and consist of an inner and outer shell of aluminum (density= 2.7 grams per cubic centimeter) about 0.3 cm thick. In between the two walls is polyurethane to improve radiation shielding of the astronauts inside."
- http://spacemath.gsfc.nasa.gov/Modules/8Mod6Prob1.pdf

"The thickness of outer wall is estimated as 1,5 g/cm (2)"
- http://adsabs.harvard.edu/abs/2014cosp...40E3366T

"the bullet's effect on the ATV's 3-millimeter-thick aluminum wall "
- http://spacenews.com/41022atv-shielding-takes-a-bullet-to-show-space-stations-stopping-power/

"The ISS is largely composed of thin-walled aluminum modules, from 1.27 millimeters (0.05 inches) to 7 millimeters (0.27 inches) thick. The air pressure from within exerts the force to keep the walls rigid."
- http://www.21stcentech.com/developed-artificial-gravity-human-space-flights/

On the last point; So in point of fact, the CANS are actually inflated as well?
My God!  It's full of universes!

Offline Burninate

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Inflatabilty is not a requirement for any space station.
It's more of an issue than a solution to a critical need.

BA modules may get there first, though, because of past circumstances and hype.

More probably, the first comercial LEO space station will have a big X painted on it's side, and it will be testing key technologies needed for a trip to mars.
Anyone knows the ISS aluminum wall width? I've calculated that if it is more than 1.1cm wide then the fabric construction is lighter per unit of surface.
"2mm aluminum pressure shell" plus unspecified graphite-epoxy shield thickness
- in figure 10 of http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20060026214.pdf

"The walls are about 10 cm thick and consist of an inner and outer shell of aluminum (density= 2.7 grams per cubic centimeter) about 0.3 cm thick. In between the two walls is polyurethane to improve radiation shielding of the astronauts inside."
- http://spacemath.gsfc.nasa.gov/Modules/8Mod6Prob1.pdf

"The thickness of outer wall is estimated as 1,5 g/cm (2)"
- http://adsabs.harvard.edu/abs/2014cosp...40E3366T

"the bullet's effect on the ATV's 3-millimeter-thick aluminum wall "
- http://spacenews.com/41022atv-shielding-takes-a-bullet-to-show-space-stations-stopping-power/

"The ISS is largely composed of thin-walled aluminum modules, from 1.27 millimeters (0.05 inches) to 7 millimeters (0.27 inches) thick. The air pressure from within exerts the force to keep the walls rigid."
- http://www.21stcentech.com/developed-artificial-gravity-human-space-flights/

On the last point; So in point of fact, the CANS are actually inflated as well?

Every pressure vessel in space is inflated.  1 atmosphere is 15 pounds per square inch.  That's a lot.  Building a human-sized cube to hold this pressure is possible, but would require many tons of material to establish the rigidity sufficient to keep the walls straight.  Instead, we use shapes that require little rigidity to hold together - cylinders and hemispheres and things which will take pressure symmetrically and channel that stress into the tension capability of the material.  Tensile strength is much cheaper in terms of mass than compressive strength or rigidity.  And a filled pressure vessel whose walls are in tension turns out to be, as a whole unit, very rigid.

Would the ISS pressure vessels collapse like a balloon if you released the pressure?  No.  They're strong enough to hold together on their own when there's negligible amounts of force on them.  But so are the Bigelow inflatables, if I understand the concept: Once you inflate them, they mostly stay in that shape rather than collapsing down to the payload fairing size.

The difference between inflated and deflated will be that the module as a whole loses a lot of buckling/bending/compressive resistance (eg, against a thrusting maneuver or a docking), and a localized region when stressed (eg, by a human foot kick) becomes much easier to deform.

The way I would interpret statements that have been made, depressurized cans are definitely stronger than the depressurized Bigelow module, but the Bigelow module isn't weak enough, and the material isn't stretchy enough, that it's going to fully collapse on its own or under gentle pressure.
« Last Edit: 04/08/2015 09:59 pm by Burninate »

Offline A_M_Swallow

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I was looking for something that would fit inside the B330 which would eliminate a wheel. I considered the possibility of a module but the only thing I could come up with was putting the module on rails running around the interior circumference of the B330. This causes all sorts of problems not the least of which is maintaining the habitat.

I had assumed that it would be put on the end of an arm in the form of a 2 blade 'propeller'.

As for maintaining the mini habitat, since it is in gravity it is on the 'floor'. The design would have to include some where for the astronaut to kneel, ladder to climb and adjustable counterweight. Enter at micro-gravity centre.

On of the advantages of putting this in a BEAM is that it is out of the astronauts way.

Offline docmordrid

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Bigelow's habs are based on NASA's TransHab tech, which Bigelow enhanced. 

AIAA presentation attached

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In  addition  to  the volume  and  storage  benefits,  TransHab  provides superior  radiation  and  micrometeoroid  protection  than conventional  aluminum  modules.

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IV.  TESTING

Hypervelocity  Impact  Testing (M/OD Protectioni:

A  variety  of hypervelocity  impact  tests,  using  different size  pruticles  at  speeds  ranging  between  2.5  through  11 km/s,  have  verified  the  TransHab  multi-shock  shield. Initial  ballistic  limit  equations  have  been  developed from  these  test  for  use  in  sh ield  optimization.  As  an example  this  sub-scale  and  full-scale  testing  has demonstrated  that  the  TransHab  shield  can  stop  a  1.7cm  diameter  aluminum  particle  traveling  at  7  km/s  fired at  both  0  and  45  degree  angles.  The  results  of these tests  have  verified  that  the  TransHab  MlOD  shield would  exceed  the  ISS  M/OD  shield  requirement  for  a habitation  module.

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The  TransHab  inflatable technology  development  program  has  proven  that  not only  are  inflatable  structures  a  viable  option,  but  they also  offer  significant  advantages  over  conventional metallic  structures.
« Last Edit: 06/21/2015 09:41 am by docmordrid »
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