back to article NASA 'naut to boldly enter pump-up space podule

NASA astronaut Jeff Williams will today enter the International Space Station's (ISS) Bigelow Expandable Activity Module (BEAM) - the pump-up podule on trial at the orbiting outpost "to investigate the potential challenges and benefits of expandable habitats for deep space exploration and commercial low-Earth orbit applications …

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"The habitat will remain attached to the ISS for two years, after which it'll be cut loose "to burn up on re-entry into Earth’s atmosphere""

Surely some museum would like to have what could be an important footnote in space history for a future exhibit and you could conduct more tests on it. I know cost is probably the reason not to do it.

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Why would this one module be worth preserving? You have to bear in mind that this same fate is envisaged for the entire ISS at some future point in time, and surely the project as a whole is more "museum-worthy" than this module.

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The module isnt made to collapse again in space. On top of that its too big for any space vessel remaining in service for return to earth. And even if it were, return handling costs would far exceed any sort of hostorical value.

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Just because you can't save it all doesn't mean you don't try to save something. I think it's important as it's far more likely that this technology will be used to build a very large percentage of future space stations if it works out. Not being able to fold it again does make that impractical however.

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No problem. Simply push it into a higher orbit that has a long life expectancy, and then, in the future, build the museum up there!

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Mascot

Computer: May I remind you, Sgt. Pinback, it was your idea to bring the alien on board in the first place... If I may quote you, you said the ship needed a mascot.

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Alien

Re: Mascot

Time to go sleepy-byes, you worthless piece of garbage!

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Childcatcher

Re: Mascot

May I remind you, Sgt. Pinback...

You have pointed the way to getting the podule back home: simply ride it down like a surf board. Let there be light!

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slow puncture

I haven't seen (too lazy for in-depth research) what the risk or mitigation is to the whole ISS if the module suffers a puncture which vents all its internal air - how drastically could it alter the station's orbit / attitude / damage structure by pushing or twisting in an unexpected direction?

Mostly idle curiosity rather than doom-mongering and I'm sure they bright boys and girls at the various agencies involved have assessed the possibilities, just haven't seen any info about it.

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Re: slow puncture

how drastically could it alter the station's orbit / attitude / damage structure by pushing or twisting in an unexpected direction?

Assuming the reaction wheels and reaction control system are still working: not much, and not for long.

A sudden venting of station air through an irregular hole would be like an inefficient cold gas thruster* in the vicinity of 50 to 60 seconds specific impulse. The 916 cubic meters of 1-bar air in the ISS amounts to (rounding up) 1200kg. The reaction control system of the station uses hypergolic, storable fuels: UDMH and nitrogen tetroxide, which should give a specific impulse of about 330 seconds.

So, a quick glance at the simplified rocket equation (delta-V = specific impulse * G * natural log [initial mass / final mass]) indicates the station would need to burn about 200kg of fuel to counter the venting of the entire station. The entire 1200kg of air would impart a delta-V of about 1.4m/s, enough to budge the station's altitude by a few kilometers.

*Pardon the redundancy: cold gas thrusters with nitrogen have a peak specific impulse of about 73 seconds, so they're inefficient to begin with.

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Re: slow puncture

okay, so assuming it was just BEAM rather than the whole station, 16m3 is about 20Kg of air at 1 bar. Annoying and disappointing but not critical. Thanks for doing the harder thinking!

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Re: slow puncture

Pressure is roughly 0.6-0.7 bar, same as most passenger planes

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Re: slow puncture

Pressure is roughly 0.6-0.7 bar, same as most passenger planes

The ISS usually runs at 14.7psi, or 1.01 bars, and BEAM is meant to equalize with it since there's no double-door airlock for astronauts to enter across a pressure differential.

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Side bet

Space is a premium up there. If they don't *have* to have the docking port back, I'm expecting them to keep it as storage.

But, If you don't announce that upfront, then it's an extra success, rather than selling it as the original intent then failing!

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Re: Side bet

Yeah, I was wondering why if it works well that they wouldn't just keep it. But your comment makes sense.

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Why not try and burst it

When it's finished with, assuming it's still there, why not try and burst it to see if it really does deflate slowly.

It would prove it one way or the other.

Alan

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Re: Why not try and burst it

The challenge in performing such an experiment would be to simulate the sheer velocity of a micro-meteorite. Probably easier to examine the results of the real thing.

The Soviets test-fired a canon in orbit in the 1970s, but it isn't around any more. Also, it shot rounds at around 700 metrews oper second, compared the *average* speed of a micrometeorite of 22,000 metres per second - though of course its slugs were bigger than a micrometeorite.

This sort of destructive testing is probably much easier on Earth, with pressure differences and temperatures controlled in a lab.

http://www.popularmechanics.com/military/weapons/a18187/here-is-the-soviet-unions-secret-space-cannon/

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Re: Why not try and burst it

"an experiment would be to simulate the sheer velocity of a micro-meteorite"

African or European micro-meteorite?

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Re: Why not try and burst it

North American...

That way the PTBs can shift velocity at the drop of a second... :-)

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Re: Why not try and burst it

Two reasons that trying to burst BEAM on the ISS accomplishes little:

1) There was plentiful materials testing on Earth, which included high velocity debris testing and scale model burst testing. Further, BEAM was preceded by Genesis I and II, which demonstrated years of on-orbit performance of inflatable structures.

2) Actively trying to burst BEAM presents the risk of explosion. Compressed air has a fair amount of energy stored in it, unlike incompressible substances such as water. Raising a structure with a safety factor of 10 (like BEAM) to its burst strength means you'll see pressures of 140-150psi in several hundred cubic feet of air: that's a bomb attached to the ISS.

In summary, burst testing can be done on Earth, has been done on Earth, so orbital burst testing offers no new information and is unnecessarily risky to perform on the ISS. Best to blow it up in an armored, instrumented test chamber, like NASA did.

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Re: Why not try and burst it

To all the naysayers,

Popping the thing *would* give the astronauts the opportunity to say "It's been swell but the swelling's gone down".

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Inflatable stations

Such structures should have multiple water tanks as part of outer skin, be wheel shaped and have the docking ports on outer skin opposite the spokes. PSU, Communications platform, gyroscopes etc at hub.

Water is additional shielding, also a source of oxygen and hydrogen if you have fission power, fusion power or a lot of solar power.

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Re: Inflatable stations

- "multiple water tanks as part of outer skin" ... They pro'lly will, should they get a few tonnes

of water going spare... ;)

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"NASA says of Williams' first foray into BEAM: "He will take an air sample, place caps on the now closed ascent vent valves, install ducting..."

Hang on...has he got a 27B/6?

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Re: Has he got a 27B/6

Well - there's a few problems filling a 27B/6 correctly ("name of street", "region code" etc)

- and lack of space for HUGE numbers in fields "value of item..." ;D :D

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I read that at first as duct taping and thought.....hang on, I am astronaut worthy.

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Re: Has he got a 27B/6

Haha, It's been while since I've seen Brazil, so had to Google '27B/6'. Of course the result i got was http://www.27bslash6.com/ home of David Thorne of 'drawing of a spider as payment for overdue bill' fame.

Nice.

Especially since my most recent televisual entertainment has been the excellent second series of 'Utopia' [Au]' (known as Dreamland in the UK and US) by Aussie comdey types Working Dog Productions.

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Possibility of an over inflated balloon situation then?

He has to manually open all the tanks and ensure that "all the air has been released". As I recall, they used air from the ISS to aid in inflating. So overpressure maybe of the tanks aren't empty?

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Anonymous Coward

I call fake

No stars, shadows wrong, no sound of the foot pump......

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Just be careful

When entering the podule, be careful not to dislodge the little inflating

VAAAAAAAAALLLLLLLVVVVVVVEEEEEEE !!

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