NASA teams evaluating ISS-built Exploration Platform roadmap

[QuantumG]

Hopefully they can sell it to Congress now.

I mean that honestly.. and the anti-SLS people should too.

http://quantumg.blogspot.com/2012/09/space-advocates-need-to-know-when-to.html

[northanger]

Union Gives Strength. —Æsop

[IRobot]

Do Bigelow modules reject radiation better than current ISS modules?

[QuantumG]

Do you mean "would"? Because they don't actually exist yet.

[IRobot]

Do you mean "would"? Because they don't actually exist yet.

What do you mean with "don't actually exist yet"? AFAIK, there are two modules up there.

[RanulfC]

Do Bigelow modules reject radiation better than current ISS modules?

Do you mean "would"? Because they don't actually exist yet.

What do you mean with "don't actually exist yet"? AFAIK, there are two modules up there.

The current models in orbit are also inside the Van-Allen belts and therefore are subject to a lot less radiation flux in the first place.

However, the same is true for the current ISS modules...

Testing of the materials used both under the TransHab program and from what I understand the more recent materials Bigelow is using have shown a marked increase in the absorbtion section (effective thickness or overall radiation protection) over aluminum modules due to the use of more poly-materials which have a better absorbtion rate. The actual radiation "protection" overall favors the TransHab/Bigelow due to the poly and water propossed sheilding, but placing water and other radiation absorbing "storage" on the outside of the ISS type modules has been suggested.

GCR performance is highly different though since the poly-material seems to show very little mitigation effects which is actually better than aluminum which tends to give off secondary radiation from GCR encounters.

In either case a "storm-shelter" would be required for extended operations outside the Van-Allens, and possibly some additional external shielding as well. More work would be required for construction similar to the current ISS modules than would be needed for the TransHab/Bigelow modules however.

IRobot: The word you're looking for is: "sheild" from radiation" rather than "reject" just FYI

Randy

[Robotbeat]

RanulfC: Quantify "a lot less." It's not the Van Allen belts that provide the shielding, by the way (it's the whole of the Earth's magnetic field, which is NOT produced via the Van Allen belts). And the difference between ISS and deep space (say, orbiting Mars) isn't THAT much. It's a factor of ~2, not a factor of 10 or 100. Really, it's the Earth's atmosphere that does the heavy lifting when it comes to shielding from radiation.

Secondary radiation from aluminum is sometimes exaggerated (it's mostly something which /mitigates/ the effectiveness of aluminum, not reverses it). If you actually quantify it, there is only a very tiny range of values of shielding thickness for which the radiation level increases for increasing shielding thickness. The vast majority of the time, adding more aluminum decreases the radiation dosage.

[Jim]

Do you mean "would"? Because they don't actually exist yet.

What do you mean with "don't actually exist yet"? AFAIK, there are two modules up there.

Not ones with all the life support systems and crew.  So ones up there are not good examples

[RanulfC]

RanulfC: Quantify "a lot less." It's not the Van Allen belts that provide the shielding, by the way (it's the whole of the Earth's magnetic field, which is NOT produced via the Van Allen belts). And the difference between ISS and deep space (say, orbiting Mars) isn't THAT much. It's a factor of ~2, not a factor of 10 or 100. Really, it's the Earth's atmosphere that does the heavy lifting when it comes to shielding from radiation.

Well I was trying to stay "shallow-but-accurate" without getting into too much detail

Lacking the ability to carry along a large "air-shield" or produce a Earth-sized magnetic field for a spacecraft it comes down to shielding ability of various materials. 

Secondary radiation from aluminum is sometimes exaggerated (it's mostly something which /mitigates/ the effectiveness of aluminum, not reverses it). If you actually quantify it, there is only a very tiny range of values of shielding thickness for which the radiation level increases for increasing shielding thickness. The vast majority of the time, adding more aluminum decreases the radiation dosage.

From what I've been reading including a lot of work on materials for Lunar and Mars habitats and extended range rovers it seems poly materials seem to come out better overall than aluminum. They seem to be better at soaking up radiation and tend to mass less than the equivilent required aluminum. I'm actually leaning towards BEO vehicles using a hybrid system with say an aluminum "storm-shelter" surrounded by water and outboard "walls" being poly, probably inflated and layered with kevlar.

Randy

[simonbp]

I mean that honestly.. and the anti-SLS people should too.

The Gateway doesn't need SLS to happen (especially if built at ISS), but would be complemented by it. And that's the line that should be used politically.

Of course, a gateway with a reusable SEP tug neatly eliminates the need for SLS Block II/IIa, even for the most ambitious Mars DRMs. And, Block II CPS scaled to fit on a Falcon Heavy would obviate the need for SLS entirely...

[Robotbeat]

Yes, poly or water are both better than aluminum. No question. The very best is liquid hydrogen (or slush hydrogen...). Stick the crew in the fuel tank? But really, that's unnecessary unless you're spending years in deep space (ala a trip to Jupiter).

[baldusi]

No, the Gateway is not for microgravity research.  The Gateway does not replace the ISS.

Just as a theoretical point. Couldn't you get better microgravity environment at EML1/2 than in LEO? You have a much smaller gravity gradient, probably less shocks, too. But only with as massive a station as the ISS.

[RocketmanUS]

Hopefully they can sell it to Congress now.

I mean that honestly.. and the anti-SLS people should too.

http://quantumg.blogspot.com/2012/09/space-advocates-need-to-know-when-to.html

Nicely written. I don't agree with all of it, however the gateway station would be an economical and right path forward to crew BLEO.

As I see it the SLS/Orion would bring crew out to EML1/2, with possible cargo on separate launches or commercial cargo ( Atlas V 551 or FH ). Modules would be assembled in LEO and sent to EML1/2 with chemical tugs or added modules.

We don't know if FH/crew Dragon will ever be launched to EML1/2. So we have also the SLS 70mt in development. As long as we get one of them we can have the EML1/2 station and they do not upgrade at least at this time the SLS 70mt block.

If the EML1/2 station is a DSH prototype all the better for a forward path to Mars and other destinations beyond the Lunar orbit. This DSH could be block I and the next the real DSH for crew to Mars, ect.

[aquanaut99]

I always thought an EML-1/2 station (or even a part-time manned space lab) is the logical next step. And with such a station SLS makes more sense. Our next objective should be studiying long-term human exposure to deep-space environment and radiation. For this, an EML-1/2 station is ideal, far better than lunar surface even, because the crew would be exposed to the full range of GCR (which isn't the case on the lunar surface where the mass of the moon shields us from half of the GCRs).

[RanulfC]

Yes, poly or water are both better than aluminum. No question. The very best is liquid hydrogen (or slush hydrogen...). Stick the crew in the fuel tank? But really, that's unnecessary unless you're spending years in deep space (ala a trip to Jupiter).

Yech... talk about "cold-storage"

Seriously I wanted to cross-post here some interesting websites and information along these lines that I stuck here:
http://forum.nasaspaceflight.com/index.php?topic=29918.msg957767#msg957767

Randy

[QuantumG]

The Gateway doesn't need SLS to happen (especially if built at ISS), but would be complemented by it. And that's the line that should be used politically.

Of course, a gateway with a reusable SEP tug neatly eliminates the need for SLS Block II/IIa, even for the most ambitious Mars DRMs. And, Block II CPS scaled to fit on a Falcon Heavy would obviate the need for SLS entirely...

Say that to a pro-SLS congressional staffer and you can say goodbye to all support for Gateway.

You need to tell them that Gateway is impossible and useless without SLS.

You need to tell them that the only way to get crews to Gateway is with Orion.

If you don't, there will be exactly one response: "NASA has been plotting behind our back to eliminate SLS!!!"

[Ben the Space Brit]

You need to tell them that Gateway is impossible and useless without SLS.

You need to tell them that the only way to get crews to Gateway is with Orion.

If you don't, there will be exactly one response: "NASA has been plotting behind our back to eliminate SLS!!!"

Which is ironic really because, in fact, what NASA has been doing is preparing a BEO mission that can survive the day, which is inevitable IMHO, when some Congressional hawk looking for risk-free good headlines cancels SLS to save money.

[Robotbeat]

Patriotism here is still too high for such a move to be entirely risk-free. To most people, that would look like canceling NASA again, unless there was some well-publishized alternative. Right now, nobody knows about SLS and they probably won't until it gets a lot closer to flight, so it could be relatively silently killed, but it is still not a risk-free move.

[clongton]

Stick the crew in the fuel tank?

Seriously - Why not?

[A_M_Swallow]

Stick the crew in the fuel tank?

Seriously - Why not?

The fuel will add lots of protection to the crew on the way there but being nearly empty little protection on the return journey.