NASASpaceFlight.com Forum
SLS / Orion / Beyond-LEO HSF - Constellation => Missions To The Near Earth Asteroids (HSF) => Topic started by: Chris Bergin on 04/03/2012 01:39 am
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Here's part 2 from the awesome DSH presentation on L2, via an article written by Chris Gebhardt:
http://www.nasaspaceflight.com/2012/04/delving-deeper-dsh-configurations-support-craft/
Part 1 is available here:
http://www.nasaspaceflight.com/2012/03/dsh-module-concepts-outlined-beo-exploration/
Specific thread for Part 1:
http://forum.nasaspaceflight.com/index.php?topic=28481.0
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Another great article!
Love the flexcraft. Looks like something out of 2001 Space Odyssey.
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That's a great article Chris G.
They really are taking to heart the lessons learned on ISS and aplying them to this DSH concept. I especially liked this note:
“Large crew quarters with no through traffic at quiet end of module."
Remembering the ISS 'float through' tours I've seen, the ambient noise (though specifically in the lab areas, but this being a much small craft) was (imo) excessive.
But to me, personally, there are two sections I think they are light on: medical and spares.
"Crew Health Care (medical) increases from 73 kg in the 60-day version to 173 kg in the 500 version."
"Personal provision weight increases from 80 kg to 100 kg between the two versions. Housekeeping expendables increase from 20 kg to 166 kg, operational spares from 100 kg to 175 kg, maintenance equipment from 40 kg to 80 kg, and EVA provisions from 30 kg to 60 kg."
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At least the single person FlexCraft can be tele-operated.
During a solar particle event would a radio signal go between the FlexCraft and the operator?
Edit:
Would the life support be able to handle 8 crew if needed ( take on crew from another DSH if it were disabled, send two for added safety if this is possible )?
What configuration are they planning on using for the 500 day mission version, with the node 1 or with out it?
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....
What configuration are they planning on using for the 500 day mission version, with the node 1 or with out it?
Both options are under consideration.
In either case, to make the 60-day DSH into the 500-day one, you (mostly) just add an extra MPLM-derived module.
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How the 400 days of Orion fits to the 500 days of the habitat?
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How the 400 days of Orion fits to the 500 days of the habitat?
Modify it for 500 days. It doesn't use peroxide propellant like Soyuz, so that should be a little easier.
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I don't want to sound like a commercial amazing people, but is there a particular reason why the do not even consider Bigelow modules? I think especially for a 500 day mission a little more room would definitely be a significant advantage.
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Another great article!
Love the flexcraft. Looks like something out of 2001 Space Odyssey.
And the MMSEV looks like it came straight from "Star Trek: The Motion Picture".
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This looks like it could eventually form the basis of a modular spacecraft that could eventually lead up to something like Nautilus-X.
I think they should make a centrifuge an option maybe look into several types from short arm to a full wheel type section.
The MMSEV and FlexCraft are esp cool.
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This looks like it could eventually form the basis of a modular spacecraft that could eventually lead up to something like Nautilus-X.
I think they should make a centrifuge an option maybe look into several types from short arm to a full wheel type section.
The MMSEV and FlexCraft are esp cool.
Yeah, that's one reason I like the Node version, even though it's slightly more massive. It's a lot more flexible, can even put a Cupola on it along with the SEV. Also makes adding, say, a Bigelow module of some sort a lot easier. Also could add a Cygnus (or Dragon) for extra storage if needed (though you'd have to qualify them for long-duration... and you'd need an arm, though that wouldn't be needed if you added the Cygnus/Dragon at ISS).
Not only that, but it's actually higher TRL, thus it can happen sooner and cheaper and with less uncertainty.
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Another great article!
Love the flexcraft. Looks like something out of 2001 Space Odyssey.
And the MMSEV looks like it came straight from "Star Trek: The Motion Picture".
Actually, look at your Disney Man in Space DVDs. Its there.
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I don't want to sound like a commercial person, but is there a particular reason why the do not even consider Bigelow modules? I think especially for a 500 day mission a little more room would definitely be a significant advantage.
It's a matter of going with what you've got. The ISS Destiny module design and capabilities are known quantities while the Bigelow inflatables, for all their advertisement, are still nonexistent. That will likely change as Bigelow becomes operational and his modules become known entities, but for now a bird in the hand is well worth 2 in the bush.
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Another great article!
Love the flexcraft. Looks like something out of 2001 Space Odyssey.
And the MMSEV looks like it came straight from "Star Trek: The Motion Picture".
Actually, look at your Disney Man in Space DVDs. Its there.
Yes it was a good idea then and now...see the cone shaped device.
http://www.youtube.com/watch?v=2fautyLuuvo&feature=related
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Does anyone know if the Boeing Lab/Hab module tooling still exists?
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Batteries for the DSH.
What are their individual mass, size, volts, amp hour rating?
What temperature range can they operate at?
How much of a charge is left after standing for 30 days unused from a full charge?
Will the SEV or single person FlexCraft use the same type of batteries as the DSH?
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Batteries for the DSH.
What are their individual mass, size, volts, amp hour rating?
What temperature range can they operate at?
How much of a charge is left after standing for 30 days unused from a full charge?
Will the SEV or single person FlexCraft use the same type of batteries as the DSH?
All TBD at this stage most likely, but comparable ratings & capabilities taken from ones used on ISS (or other existing spacecraft)
correction: from (a snippet of) L2 information: DSH power systems are either off the shelf, or MPCV derived
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Batteries for the DSH.
What are their individual mass, size, volts, amp hour rating?
1.11 kg
53 mm dia x 250 mm height
3.6 V
50 Ah nominal
What temperature range can they operate at?
Charge + 10°C to + 35°C
Discharge 0°C to + 40°C
[SAFT VES 180 from the Smitherman presentation 8) *you* linked 4 days ago in the other thread... page 24]
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Batteries for the DSH.
What are their individual mass, size, volts, amp hour rating?
1.11 kg
53 mm dia x 250 mm height
3.6 V
50 Ah nominal
What temperature range can they operate at?
Charge + 10°C to + 35°C
Discharge 0°C to + 40°C
[SAFT VES 180 from the Smitherman presentation 8) *you* linked 4 days ago in the other thread... page 24]
Thank you
Just found a web page on the batteries and a PDF
http://www.saftbatteries.com/Produit_Space_VES_cell_range_301_58/Default.aspx#DL2
PDF
http://www.saftbatteries.com/doc/Documents/space/Cube712/VES%20180.e9cf5d8f-3cbd-4921-8ac0-89d7b13bd0c0.pdf
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Could the 500 day version be used for an EML2 starter station with the node 1?
Add remote manipulator arms , two I think would be better than one. Out that far from LEO if one did not work then we would have the other one to use.
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Add remote manipulator arms
Why?
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Add remote manipulator arms
Why?
Good question.
So it can add modules, connect the Cygnus or like it for resupply, ect.
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Add remote manipulator arms
Why?
Good question.
So it can add modules, connect the Cygnus or like it for resupply, ect.
At EML1/2 spacestation the arms can be used to:
Transfer unpressurised cargo from the LV to a reusable lunar lander
Attach and detach refuelling pipes
Repair landers and Mars transfer vehicles for instance by acting as the space crane when replacing an engine
Move astronauts around when they are performing an EVA
Move spacecraft from the docking ports to the holding bays
Permit the berthing of spacecraft
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Add remote manipulator arms
Why?
Good question.
So it can add modules, connect the Cygnus or like it for resupply, ect.
At EML1/2 spacestation the arms can be used to:
Transfer unpressurised cargo from the LV to a reusable lunar lander
Attach and detach refuelling pipes
Repair landers and Mars transfer vehicles for instance by acting as the space crane when replacing an engine
Move astronauts around when they are performing an EVA
Move spacecraft from the docking ports to the holding bays
Permit the berthing of spacecraft
Jim, are you asking why we need to do these things with an arm? I can't answer that question but I'll ask; is an arm the best way to do these things? Are these activities that can be avoided based on design? Is an arm the least expensive option? Do we want an arm or do we need an arm?
Either way is fine by me as long as it is the fastest way to get some exploration started. This is when I would like to be able to earmark my income taxes, I'd check the NASA box.
Rob
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Add remote manipulator arms
Why?
Indeed an arm is NOT required, a DSH can be assembled at ISS. And since ISPR's will likely be integrated and not moved from module to module, direct docking will be the perferred method, especially since there will likely be periods when it is unmanned (grapple/berth requires a crew) If we are talking about EVA acess for repair, Strela (or whatever its real name is) would probably be lighter and cheaper, and most importantly do the job.
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Add remote manipulator arms
Why?
I've said this before in answer to the same question from the same poster. A RMS is a 'nice to have' on a large, deep-space spaceship. It allows you to do extra stuff like docking without needing active-thruster docking far from Earth. It also allows berthing of pre-positioned assets like cargo pods meaning that you don't automatically have to carry all the mission payload all the way from LEO. Berthing means large CBM-style interfaces rather than narrow LIDS-style ones meaning you can carry larger items, potentially leading to easier installation and swap-out of equipment. A large RMS will also allow crew-members on maintenance EVAs (a certainty on a long flight) to get to where they need to be without having to laboriously crawl along the hull.
An RMS is hardly a necessity but it does add capability and mission flexibility to the spacecraft. I know that I'd like one if I was a mission planner for a Mars or other Inner Planets exploration mission.
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Add remote manipulator arms
Why?
Indeed an arm is NOT required, a DSH can be assembled at ISS. And since ISPR's will likely be integrated and not moved from module to module, direct docking will be the perferred method, especially since there will likely be periods when it is unmanned (grapple/berth requires a crew) If we are talking about EVA acess for repair, Strela (or whatever its real name is) would probably be lighter and cheaper, and most importantly do the job.
The Mobile Servicing System requires a crew but automated grappling and berthing was demonstrated by Orbital Express.
Add remote manipulator arms
Why?
Good question.
So it can add modules, connect the Cygnus or like it for resupply, ect.
Although I guess a small robotic arm who's only purpose would be to berth re-supply vehicles wouldn't be too expensive. But then again how much larger is CBM transfer passage in comparison to NDS' 32 inches?
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Add remote manipulator arms
Why?
Indeed an arm is NOT required, a DSH can be assembled at ISS. And since ISPR's will likely be integrated and not moved from module to module, direct docking will be the perferred method, especially since there will likely be periods when it is unmanned (grapple/berth requires a crew) If we are talking about EVA acess for repair, Strela (or whatever its real name is) would probably be lighter and cheaper, and most importantly do the job.
The Mobile Servicing System requires a crew but automated grappling and berthing was demonstrated by Orbital Express.
Add remote manipulator arms
Why?
Good question.
So it can add modules, connect the Cygnus or like it for resupply, ect.
Although I guess a small robotic arm who's only purpose would be to berth re-supply vehicles wouldn't be too expensive. But then again how much larger is CBM transfer passage in comparison to NDS' 32 inches?
CBM 50' diagonal , it is a square opening.
RMA is for adding parts to an EML1/2 station also. The station might not be assembled or at least not totally assembled at ISS. Less mass to get out to EML1/2. Nice to have the option of the RMS. Can start out with one and add the other later. If something goes wrong with an automated docking of a resupply vehicle the there could be the option to use a RMA.
How fast does the RMS move on the ISS to berth the Dragon or Cygnus. Is in not slow enough to use remote control from Earth if we wanted to.
Other good replies above for use of a RMA.
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If they use a SEP tug, then more mass in LEO is not a problem. In fact, it's a lot more efficient to build it ALL in LEO and push it up with the tug than to build some of it in LEO and some at EML1/2.
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If they use a SEP tug, then more mass in LEO is not a problem. In fact, it's a lot more efficient to build it ALL in LEO and push it up with the tug than to build some of it in LEO and some at EML1/2.
All good when we get SEP. For now I'd like to keep the option and the ability for it to grow or assemble other platforms in and for EML1/2 ect.
Then there is repairs or replacements.( EDIT: for the station )
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If they use a SEP tug, then more mass in LEO is not a problem. In fact, it's a lot more efficient to build it ALL in LEO and push it up with the tug than to build some of it in LEO and some at EML1/2.
All good when we get SEP. For now I'd like to keep the option and the ability for it to grow or assemble other platforms in and for EML1/2 ect.
Then there is repairs or replacements.
SEP is short-term. A modified Boeing 702 can do at least up to 100kW, and already supports electric propulsion. Actually, the electric-propulsion-only version is their cheapest, I believe (though not 100kW).
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This presentation is awesome.
http://spirit.as.utexas.edu/~fiso/telecon/Raftery_5-25-11/Raftery_5-25-11.pdf
Shows how we can scale up from a 100-250kW tug for moving the DSH/Gateway from ISS to EML1/2, then a 250-400kW propulsion module departs from the EML1/2 gateway with a dedicated hab to an asteroid and back (possibly using iCPS/CPS for an initial boost), then a 1000kW solar-electric propulsion module to move a larger hab from the EML1/2 gateway to Mars orbit to rendezvous with a pre-placed Mars lander.
This has a much lower IMLEO for a Mars mission than the older NTR-based Mars DRM 5. Also uses much nearer-term propulsion (NTR is not near-term). And the architecture is reusable, since the whole MTV returns to the EML1/2 exploration gateway. Only thing not reusable for Mars missions is the lander (surface hab is pre-placed on Mars).
Anyway, very interesting. Very feasible with just incremental improvements. Wouldn't need a huge launch campaign like Mars DRM 5, and also doesn't need NTR (which just won't be happening anytime soon, let's all be honest... and that's coming from myself as an evangelist for nuclear power on Earth).
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By the way, I've discovered the presentation that the article is based on in the public domain (no, not the NASASpaceflight.com-watermarked one).
And I could post it right here, but I won't BECAUSE YOU SHOULD ALL HAVE L2 ANYWAY! ;)
(If you really can't afford L2, PM and I'll give you the link.)
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CBM 50' diagonal , it is a square opening.
RMA is for adding parts to an EML1/2 station also. The station might not be assembled or at least not totally assembled at ISS. Less mass to get out to EML1/2. Nice to have the option of the RMS. Can start out with one and add the other later. If something goes wrong with an automated docking of a resupply vehicle the there could be the option to use a RMA.
How fast does the RMS move on the ISS to berth the Dragon or Cygnus. Is in not slow enough to use remote control from Earth if we wanted to.
Other good replies above for use of a RMA.
An RMS also can simplify berthing of vehicles like the SEV and be used to assist in inspection and repair of the spacecraft.
I think it should be able to inch worm across the vehicle like the one on ISS.
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By the way, I've discovered the presentation that the article is based on in the public domain (no, not the NASASpaceflight.com-watermarked one).
And I could post it right here, but I won't BECAUSE YOU SHOULD ALL HAVE L2 ANYWAY! ;)
(If you really can't afford L2, PM and I'll give you the link.)
Good man, that's so nice to see (your comment!)
As such you can post it on this thread. I've locked the L2 version as it's now public domain.
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By the way, I've discovered the presentation that the article is based on in the public domain (no, not the NASASpaceflight.com-watermarked one).
And I could post it right here, but I won't BECAUSE YOU SHOULD ALL HAVE L2 ANYWAY! ;)
(If you really can't afford L2, PM and I'll give you the link.)
Good man, that's so nice to see (your comment!)
As such you can post it on this thread. I've locked the L2 version as it's now public domain.
Okay, here it is:
http://spirit.as.utexas.edu/~fiso/telecon/Smitherman_3-14-12/Smitherman_3-14-12.pdf
There's MP3 audio of the teleconference where the author presents. It explains more details:
http://spirit.as.utexas.edu/~fiso/telecon/Smitherman_3-14-12/Smitherman.mp3
By the way, there's a ton of somewhat-related presentations in here:
http://spirit.as.utexas.edu/~fiso/telecon/
Lots of information to mine in there. Great ideas.
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If we get DSH as an EML2 station then it would help in finding out how crew handles space outside LEO for longer time periods than Apollo before we land on the moon , go to NEO, or Mars. So that could be a few missions till we have a lunar lander ( U.S. made or foreign partner made lander ).
If we get the EML2 station and Orion to it then a lunar partner might show up?
At least the high TRL with higher mass DSH design would most likely get us the EML2 station sooner and allow us to develop the lighter DSH for NEO and Mars based on our experience with a DSH based EML2 station.
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Okay, here it is:
http://spirit.as.utexas.edu/~fiso/telecon/Smitherman_3-14-12/Smitherman_3-14-12.pdf
There's MP3 audio of the teleconference where the author presents. It explains more details:
http://spirit.as.utexas.edu/~fiso/telecon/Smitherman_3-14-12/Smitherman.mp3
By the way, there's a ton of somewhat-related presentations in here:
http://spirit.as.utexas.edu/~fiso/telecon/
Lots of information to mine in there. Great ideas.
One thing that I don't understand about the proposal is the tunnel, which is a new build. Why not instead use a shuttle airlock like the other proposal, which gives you the sideways hatch anyhow? The only thing sacrificed would be the ability to move racks from the MPLM to the Hab, and frankly it doesn't look like that is needed anyhow.
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Okay, here it is:
http://spirit.as.utexas.edu/~fiso/telecon/Smitherman_3-14-12/Smitherman_3-14-12.pdf
There's MP3 audio of the teleconference where the author presents. It explains more details:
http://spirit.as.utexas.edu/~fiso/telecon/Smitherman_3-14-12/Smitherman.mp3
By the way, there's a ton of somewhat-related presentations in here:
http://spirit.as.utexas.edu/~fiso/telecon/
Lots of information to mine in there. Great ideas.
One thing that I don't understand about the proposal is the tunnel, which is a new build. Why not instead use a shuttle airlock like the other proposal, which gives you the sideways hatch anyhow? The only thing sacrificed would be the ability to move racks from the MPLM to the Hab, and frankly it doesn't look like that is needed anyhow.
I’d rather doubt to use a shuttle airlock. They are like nearing 30 years old. Like you however I would probably prefer a built in airlock of some type rather than have the tunnel serve as one.
My guess is they expect something like the SEV to function as airlock and be available for every mission. The tunnel air lock would worry me because it would cut you off from supplies in the other part of the ship.
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By the way, there's a ton of somewhat-related presentations in here:
http://spirit.as.utexas.edu/~fiso/telecon/
Lots of information to mine in there. Great ideas.
The Hatfield doc is also linked by Chris from here:-
http://forum.nasaspaceflight.com/index.php?topic=27446.0 (http://forum.nasaspaceflight.com/index.php?topic=27446.0)
cheers, Martin
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Having read about the design of the Deep Space Hab and vehicles, I see the radiation protection rating of them is to be 11cm/gm2. Is this going to be enough protection against major solar flares?
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The tunnel air lock would worry me because it would cut you off from supplies in the other part of the ship.
That would worry me as well because it makes the airlock a single-point failure. It could potentially be catastrophic for the mission and crew. It would be far better to have an isolated airlock that didn't cut the spacecraft in half.
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Perhaps they should come up with a derivative of the small, Pirs docking module built by Russia for ISS? It masses about 3.5 tons and is about the same size as a front Soyuz orbital module.
http://en.wikipedia.org/wiki/Pirs_(ISS_module)
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What about using suit ports?
http://wiki.nasa.gov/cm/blog/analogsfieldtesting/posts/post_1250519466168.html
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The tunnel air lock would worry me because it would cut you off from supplies in the other part of the ship.
That would worry me as well because it makes the airlock a single-point failure. It could potentially be catastrophic for the mission and crew. It would be far better to have an isolated airlock that didn't cut the spacecraft in half.
I agree.
Another concern of mine is the suit-lock idea for the MMSEV. Are they imagining two EVA suits permanently attached on the outside of the craft for the 500 day journey? It seems like the EVA suits would require significant redesign to be able to be stored on the outside of a craft for such an extended time. The suit lock idea seems to have a lot of merit for a dusty planetary environment - but it would seem better to have a real airlock (or depress the entire cabin if only a few of 2).
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The tunnel air lock would worry me because it would cut you off from supplies in the other part of the ship.
That would worry me as well because it makes the airlock a single-point failure. It could potentially be catastrophic for the mission and crew. It would be far better to have an isolated airlock that didn't cut the spacecraft in half.
I agree.
Another concern of mine is the suit-lock idea for the MMSEV. Are they imagining two EVA suits permanently attached on the outside of the craft for the 500 day journey? It seems like the EVA suits would require significant redesign to be able to be stored on the outside of a craft for such an extended time. The suit lock idea seems to have a lot of merit for a dusty planetary environment - but it would seem better to have a real airlock (or depress the entire cabin if only a few of 2).
I one of the pictures they had a cover that went over the suit ports ( at least for the land version ).
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{snip}
Another concern of mine is the suit-lock idea for the MMSEV. Are they imagining two EVA suits permanently attached on the outside of the craft for the 500 day journey? It seems like the EVA suits would require significant redesign to be able to be stored on the outside of a craft for such an extended time. The suit lock idea seems to have a lot of merit for a dusty planetary environment - but it would seem better to have a real airlock (or depress the entire cabin if only a few of 2).
I one of the pictures they had a cover that went over the suit ports ( at least for the land version ).
Is the cover air tight? A dust cover may only be rain proof.
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{snip}
Another concern of mine is the suit-lock idea for the MMSEV. Are they imagining two EVA suits permanently attached on the outside of the craft for the 500 day journey? It seems like the EVA suits would require significant redesign to be able to be stored on the outside of a craft for such an extended time. The suit lock idea seems to have a lot of merit for a dusty planetary environment - but it would seem better to have a real airlock (or depress the entire cabin if only a few of 2).
I one of the pictures they had a cover that went over the suit ports ( at least for the land version ).
Is the cover air tight? A dust cover may only be rain proof.
On the moon there is no air. Cover just needs to keep out the dust and small particles. In space , keep out small particles and objects.
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{snip}
Another concern of mine is the suit-lock idea for the MMSEV. Are they imagining two EVA suits permanently attached on the outside of the craft for the 500 day journey? It seems like the EVA suits would require significant redesign to be able to be stored on the outside of a craft for such an extended time. The suit lock idea seems to have a lot of merit for a dusty planetary environment - but it would seem better to have a real airlock (or depress the entire cabin if only a few of 2).
I one of the pictures they had a cover that went over the suit ports ( at least for the land version ).
Is the cover air tight? A dust cover may only be rain proof.
On the moon there is no air. Cover just needs to keep out the dust and small particles. In space , keep out small particles and objects.
"On the Moon there is no air." - Except inside the rover. The air tight seal would be there to keep the air in. This is a back up to the suit lock.
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{snip}
Another concern of mine is the suit-lock idea for the MMSEV. Are they imagining two EVA suits permanently attached on the outside of the craft for the 500 day journey? It seems like the EVA suits would require significant redesign to be able to be stored on the outside of a craft for such an extended time. The suit lock idea seems to have a lot of merit for a dusty planetary environment - but it would seem better to have a real airlock (or depress the entire cabin if only a few of 2).
I one of the pictures they had a cover that went over the suit ports ( at least for the land version ).
Is the cover air tight? A dust cover may only be rain proof.
On the moon there is no air. Cover just needs to keep out the dust and small particles. In space , keep out small particles and objects.
"On the Moon there is no air." - Except inside the rover. The air tight seal would be there to keep the air in. This is a back up to the suit lock.
I see your point.
Don't know if it is are tight as a back up or not. If it does not add to much mass that would be a good idea to have the cover air tight. Should be no problem in making it that way, at least as a back up. Even if it did not totally stop the air from leaking it could then slow down the loss rate long enough to seal the leak from the inside of the crew cabin.
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I agree.
Another concern of mine is the suit-lock idea for the MMSEV. Are they imagining two EVA suits permanently attached on the outside of the craft for the 500 day journey? It seems like the EVA suits would require significant redesign to be able to be stored on the outside of a craft for such an extended time. The suit lock idea seems to have a lot of merit for a dusty planetary environment - but it would seem better to have a real airlock (or depress the entire cabin if only a few of 2).
The DSH and MMSEV would be used for an astriod mission so you would need protetion from dust. Also with suit locks you still need a real airlock for back up and to allow you to take stuff inside and out. The idea of the suitlock is to keep the outside out.
Depressing the cabin is the least flexable way to do it. I makes all crew memebers need to use a space suit or head to a part of the spacecraft that is airtight. For the MMSEV not bad idea perhaps as you could design it in.
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Here's the back covering for the old style LER.
But is keeping dust out really important?
It makes me wonder how much lunar dust there is in those Apollo command modules and if it caused any problem at all on any mission. ???
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Here's the back covering for the old style LER.
But is keeping dust out really important?
It makes me wonder how much lunar dust there is in those Apollo command modules and if it caused any problem at all on any mission. ???
Yes, they complained of sneazing. The dust also scracthed up the glass of the space suit helmit. It has some toxic properties and really not good for breathing or the equipment inside(i.e. it can clog things up).
Apollo was a short mission, they only spent a very little time on the moon. Longer missions would be spending more time on the moon, mars, or an NEO could be more problematic.
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Here's the back covering for the old style LER.
But is keeping dust out really important?
Lunar regolith sticks to everything and is toxic to humans, although the Apollo astronauts weren't exposed enough to cause any permanent damage. The dust can also prevent a proper seal.
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A mockup/simulator of the DSH and support systems are being built at Marshall:
"The Concept Demonstrator is being assembled and outfitted in Building 4649 at Marshall Space Flight Center in Huntsville, Ala."
http://www.nasa.gov/exploration/technology/deep_space_habitat/constructing-demonstrators.html
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CONOPS for DSH and asteroids
http://spirit.as.utexas.edu/~fiso/telecon/Zimmer_10-17-12/
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CONOPS for DSH and asteroids
http://spirit.as.utexas.edu/~fiso/telecon/Zimmer_10-17-12/
Quite interesting. It has a detailed examination of mission opportunities to known NEAs and constructs a possible campaign.
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attached is a document with full NASA briefs on the DSH as of 12/2011
I don't recall this being posted before.
Also attached is a sensitivity analysis for DSH radiation issues - its not pretty.
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attached is a document with full NASA briefs on the DSH as of 12/2011
I don't recall this being posted before.
Also attached is a sensitivity analysis for DSH radiation issues - its not pretty.
Ouch! The exposure chart for previous missions (page 18) shows very clearly that ISS astronauts have gone right up to the 150mSv lifetime limit. That would probably explain why some US astronauts are banned from flying in the proposed full-year missions to ISS.
And the remainder of the document is sobering as well. Some of the proposed NEA missions will go way over the imposed lifetime radiation limit. No wonder the document opens with the statement that limiting the amount of exposure to Galactic Cosmic Radiation (GCR) is "the sound-barrier to break" before real BEO exploration can take place.
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[No wonder the document opens with the statement that limiting the amount of exposure to Galactic Cosmic Radiation (GCR) is "the sound-barrier to break" before real BEO exploration can take place.
It's clear that it's the elephant sitting in the middle of the room.
IMHO, as no-one is seriously talking about an aircraft-carrier-sized DSH with most of its mass made up of shielding, it makes the EML spacelab even more important. That would allow for testing of mitigation methods and technologies in the BEO environment but also with an easy Earth return in the event of an emergency. The NEO missions simply wouldn't provide that.
[edit]
Just an additional point: This is only going to be possible if there is a standing rule of: "Nothing is unthinkable". Flying with huge unfurling sun-shades (as on JWST)? Composite-hulled inflatable habs with a water layer on the inside? It's clear that this is a big unknown area and it's going to take a lot of effort (and money - horror of horrors!) to fix.
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If nothing is unthinkable, then we can consider other options like just increasing the limit or combining it with drugs or an antioxidant cocktail to deal with the limits or use older astronauts with a higher limit.
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[No wonder the document opens with the statement that limiting the amount of exposure to Galactic Cosmic Radiation (GCR) is "the sound-barrier to break" before real BEO exploration can take place.
It's clear that it's the elephant sitting in the middle of the room.
IMHO, as no-one is seriously talking about an aircraft-carrier-sized DSH with most of its mass made up of shielding, it makes the EML spacelab even more important. That would allow for testing of mitigation methods and technologies in the BEO environment but also with an easy Earth return in the event of an emergency. The NEO missions simply wouldn't provide that.
[edit]
Just an additional point: This is only going to be possible if there is a standing rule of: "Nothing is unthinkable". Flying with huge unfurling sun-shades (as on JWST)? Composite-hulled inflatable habs with a water layer on the inside? It's clear that this is a big unknown area and it's going to take a lot of effort (and money - horror of horrors!) to fix.
Although SPE shielding in the form a specific storm shelter area will be incorporated into the DSH, we would not expect to generically use dead mass shielding as a primary go forward solution for GCR
At least the studies are starting to acknowledge that while a thick layer of suitable material is effective for SPE, it is impossible to provide protection from GCR without active shielding.
However, no provision is included in the architecture for mass:
Total wet mass estimates of 34,009 kg including cargo radiation protection of 2,055 kg. Launch Cost estimates at $5000/kg of the SPE shielding only range from ~$100M to $1B.
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NEA will not provide GCR protection?! Good luck with that requirement change.....
What is the cost to train crew that can only have a 14 day tour of duty at L2 before their careers are over given the lack of GCR protection cited in these studies? Time to reach NEA?
Drugs? name them and the effectiveness. FDA approved?
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The good news is that active system estimates are in the 30,000kg range for the size stated. (Before you ask: No, it can be sent in pieces, so don't start talking about 70,000 kg HLV requirements.) Multiply by either SLS like ~$100,000/kg or $5000/kg with depot centric. The GCR reduction would be about an order of magnitude.
Active systems will require cryocoolers, and likely much colder than LOX (90K) when the optimal trade of cryocooler weight versus active system weight is considered, despite assertions that the low temperatures can be achieved passively. IOW: a sunshield is not going to be sufficient--the solution requires active cryocoolers. Subscale systems of course, would be deployed first--sound exciting, lots of R&D + mission ops for repair and replacement.
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Will active systems work? No one is sure, no one will try, but somehow folks can still type on keyboards. That is why a L2 stepping stone is critical: it focusses NASA on its key challenges (well not exactly...see below...). If it does not work, i suppose NASA's destination is to the moon to live like a mole. what is the hurry? Afraid to try? try again? So once the L2 habitat is in place, it gives NASA a critical R&D facility, and the lunar missions can commence. It would seem to be that HSF finally has a long term critical science goal other than the wrong g-level bone loss studies and guaranteed spinoffs back to earth. Milli-g may be the answer for the trip to Mars. Of course, taking a spin in LEO is the first step because GCR protection is not required.
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A lot of money?
Even better is that the dollars spent on GCR protection will have numerous benefits back on earth. More on this later. Development costs will be substantially less than a new (unnecessary) engine program for this critical area to enable Exploration. Is this "alot of money"?
With R&D, there are known areas ripe to reduce the weights further from the SOA, which appears to be cost effective R&D to meet a critical need. Authorized but not appropriated.
Depot centric architectures are most cost effective with ZBO LEO depots, not passive depots, so common cryocooler technology can both bring launch costs down and help solve the critical crew health issue with GCR. Recall that with a depot, the launch vehicle size can be reduced dramatically and the flight rate is increased reducing IMLEO costs. Likely need a cryocooler for all that ISRU product too. Does the depot spin and could a tether be attached to a 100,000+ kg (when fueled) piece of hardware to study constant milli-g health affects? Authorized but not appropriated.
Oh well, back to reality: 99% of the funds are spent on J2X, 5-seg, SSME to RS68 to SSME, liquid strap ons, Orion without GCR, ...... nothing to do with the NASA technology challenges, all thanks to the 2000 to 2008 fiscally conservative Congress and the 2010 NASA Authorization Act. Authorized and appropriated. congrats.
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Also note that even the
NASA Technology Grand Challenges (http://www.nasa.gov/pdf/503466main_space_tech_grand_challenges_12_02_10.pdf) do not include radiation under Space Heath and Medicine, but it appears to be a problem for robotics. ???
Surviving Extreme Space Environments
Enable robotic operations and survival......
Problem: Space travel can present extreme environments that affect machine operations and survival. Like humans, machines are impacted by gravity, propulsive forces, radiation,....
Space Health and Medicine
Eliminate or mitigate the negative effects of the space environments on human physical and behavioral health, optimize human performance in space and expand the scope of space based medical care to match terrestrial care.
Problem: Space is an extreme environment that is not conducive to human life. Today’s technology can only partially mitigate the effects on the physical and psychological well-being of people. In order to live and effectively work in space for an extended period of time, people require technologies that enable survival in extreme environments; countermeasures that mitigate the negative effects of space; accommodations that optimize human performance; comprehensive space-based physiological and physical health management and prompt and comprehensive medical care in a limited infrastructure.
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attached is a document with full NASA briefs on the DSH as of 12/2011
I don't recall this being posted before.
Also attached is a sensitivity analysis for DSH radiation issues - its not pretty.
Thanks for that. For reference, here's a table giving a general orientation to radiation effects.
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attached is a document with full NASA briefs on the DSH as of 12/2011
I don't recall this being posted before.
Also attached is a sensitivity analysis for DSH radiation issues - its not pretty.
Thanks for that. For reference, here's a table giving a general orientation to radiation effects.
That table says that the make career astronaut dose is 1,500mSv, while the Lora Bailey report above says 150mSv for lifetime limit "goal". Quite a difference.
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attached is a document with full NASA briefs on the DSH as of 12/2011
I don't recall this being posted before.
Also attached is a sensitivity analysis for DSH radiation issues - its not pretty.
Thanks for that. For reference, here's a table giving a general orientation to radiation effects.
That table says that the make career astronaut dose is 1,500mSv, while the Lora Bailey report above says 150mSv for lifetime limit "goal". Quite a difference.
Yes, it is. I don't know the ins and outs of radiation medicine, but note that 150 mSv is what we old guys used to call 15 rem, which is considerably below the threshold of noticeable effects for "radiation sickness." Of course, the study under discussion here is concerned with increased cancer risk, a totally different thing.
Is there a radiologist in the house?
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There are many contributing factors to cancer, including diet, exercise, stress, immune system health and many others. When becoming an astronaut all these factors change. Singling out radiation is a mistake in my opinion.
If you get cancer probability of death depends on how early the cancer is discovered and standard of treatment. Astronauts and ex-astronauts will have the highest level of health care.
Death rates from cancer are falling (by 16% in Britain in the last decade, partly due to reduction in smoking, partly better treatment). Using the death rate now (even if they have used up-to-date figures) will lead to an overestimate for when the missions are planned for.
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How to solve this problem? Send smokers without their cigarettes (plentiful patches). Net decrease in cancer risk.
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[No wonder the document opens with the statement that limiting the amount of exposure to Galactic Cosmic Radiation (GCR) is "the sound-barrier to break" before real BEO exploration can take place.
It's clear that it's the elephant sitting in the middle of the room.
IMHO, as no-one is seriously talking about an aircraft-carrier-sized DSH with most of its mass made up of shielding, it makes the EML spacelab even more important. That would allow for testing of mitigation methods and technologies in the BEO environment but also with an easy Earth return in the event of an emergency. The NEO missions simply wouldn't provide that.
[edit]
Just an additional point: This is only going to be possible if there is a standing rule of: "Nothing is unthinkable". Flying with huge unfurling sun-shades (as on JWST)? Composite-hulled inflatable habs with a water layer on the inside? It's clear that this is a big unknown area and it's going to take a lot of effort (and money - horror of horrors!) to fix.
Although SPE shielding in the form a specific storm shelter area will be incorporated into the DSH, we would not expect to generically use dead mass shielding as a primary go forward solution for GCR
At least the studies are starting to acknowledge that while a thick layer of suitable material is effective for SPE, it is impossible to provide protection from GCR without active shielding.
...
Actually, that's false. Do you know just how large of a magnetic field is necessary to block GCR? I calculated it, once... It'd be like being INSIDE of an MRI machine. If you move too fast, you'll get a metal taste in your mouth (and possibly a headache?) because your body is conducting and moving a wire through a magnetic field causes a current to flow. No. Active shielding is better for solar particle radiation, and except at extremes is worthless for GCR.
If you use a thick enough (passive) shield, you can block GCR. It's absolutely not impossible. The lightest way to do this is liquid hydrogen.
I wish people who don't actually know what they're talking about would stop strongly asserting things about space radiation. It adds unnecessary confusion and is quite counter-productive.
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I wish people who don't actually know what they're talking about would stop strongly asserting things about space radiation. It adds unnecessary confusion and is quite counter-productive.
I, for one, am presently extremely confused about everything GCR, at least so far as their impact on spaceflight is concerned.
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I wish people who don't actually know what they're talking about would stop strongly asserting things about space radiation. It adds unnecessary confusion and is quite counter-productive.
I, for one, am presently extremely confused about everything GCR, at least so far as their impact on spaceflight is concerned.
Some clarity:
The effect is not acute. In other words, the effect of GCR is long-term and doesn't (for the most part) affect the capability of the astronauts to perform the mission. The effect, if any, is on future cancer incidence rates (and isn't worse than smoking).
Also, it takes a lot to shield from GCR. The atmosphere of Mars shields part of GCRs, and regolith piled on top of a habitat on the Moon, on Mars, or on an asteroid could reduce GCR incidence.
GCR doses are higher during Solar Minimum (i.e. when there are fewer solar particle events) and lower during Solar Maximum. The solar cycle repeats every 11 years (essentially... it's actually a ~22 year period, but the effect for GCR is a repeat every 11 years), and we are entering Solar Maximum right now. The difference is roughly a factor of 2.
GCRs are made of charged ions at high energy (many relativistic, i.e. near the speed of light).
To first order, more shielding mass means less radiation. But hydrogen is a few times more effective than other elements for shielding. (and for a small range of metal shielding thicknesses, total radiation dose can increase slightly with increasing shield thickness... but that is a small range). GCRs produce much of their damaging effect through secondary particles... I.e. the big charged ions hit some matter and produce a secondary shower of particles... but usually, adding more shielding will still reduce total dosages.
GCRs come in from all directions essentially evenly (except when on or near the surface of a large body, of course). Because of their high momentum, they are only barely affected by magnetic fields. If the Earth had no atmosphere, we would experience a very large flux (though still somewhat attenuated flux) of GCRs on the Earth's surface, in spite of the Earth's large geomagnetic field... It is the Earth's atmosphere that does the most heavy lifting when it comes to shielding us from space radiation.
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Actually, that's false. Do you know just how large of a magnetic field is necessary to block GCR? I calculated it, once... It'd be like being INSIDE of an MRI machine. If you move too fast, you'll get a metal taste in your mouth (and possibly a headache?) because your body is conducting and moving a wire through a magnetic field causes a current to flow. No. Active shielding is better for solar particle radiation, and except at extremes is worthless for GCR.
If you use a thick enough (passive) shield, you can block GCR. It's absolutely not impossible. The lightest way to do this is liquid hydrogen.
I wish people who don't actually know what they're talking about would stop strongly asserting things about space radiation. It adds unnecessary confusion and is quite counter-productive.
There are magnet windings around a torus that allow you to have arbitrarily high magnetic field strength that fades to a uniform zero in the "donut hole" of the torus. Not saying it's easy, but that's one solution.
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Actually, that's false. Do you know just how large of a magnetic field is necessary to block GCR? I calculated it, once... It'd be like being INSIDE of an MRI machine. If you move too fast, you'll get a metal taste in your mouth (and possibly a headache?) because your body is conducting and moving a wire through a magnetic field causes a current to flow. No. Active shielding is better for solar particle radiation, and except at extremes is worthless for GCR.
If you use a thick enough (passive) shield, you can block GCR. It's absolutely not impossible. The lightest way to do this is liquid hydrogen.
I wish people who don't actually know what they're talking about would stop strongly asserting things about space radiation. It adds unnecessary confusion and is quite counter-productive.
There are magnet windings around a torus that allow you to have arbitrarily high magnetic field strength that fades to a uniform zero in the "donut hole" of the torus. Not saying it's easy, but that's one solution.
That is true. But it's not terribly practical, since you're still talking about several Tesla fields, and even the residual field is likely to be large in that case.
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One benefit of high magnetic field gradients is another potential form of artificial gravity... ;)
(but again, not practical... You can get a headache from moving your head around too fast in a field that large)
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There are magnet windings around a torus that allow you to have arbitrarily high magnetic field strength that fades to a uniform zero in the "donut hole" of the torus. Not saying it's easy, but that's one solution.
That is true. But it's not terribly practical, since you're still talking about several Tesla fields, and even the residual field is likely to be large in that case.
I may still have a circa-2005 MATLAB code kicking around that covers the geometry I'm thinking of. I had thought that the internal field is completely independent of the surrounding field strength, but I'm reaching back to a sophomore year research task, back when I was bright-eyed, bushy-tailed, and didn't know any better. You're the physicist, you ever read anything by Rainer Meinke on double helix superconducting coils?
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There are magnet windings around a torus that allow you to have arbitrarily high magnetic field strength that fades to a uniform zero in the "donut hole" of the torus. Not saying it's easy, but that's one solution.
That is true. But it's not terribly practical, since you're still talking about several Tesla fields, and even the residual field is likely to be large in that case.
I may still have a circa-2005 MATLAB code kicking around that covers the geometry I'm thinking of. I had thought that the internal field is completely independent of the surrounding field strength, but I'm reaching back to a sophomore year research task, back when I was bright-eyed, bushy-tailed, and didn't know any better. You're the physicist, you ever read anything by Rainer Meinke on double helix superconducting coils?
I have no doubt you are correct, but what you are saying rings no bells. (I'm taking a 500-level ENM course next semester, though.)
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Not the scrawny little arms again!
No, NO, NO, NO, Hee-haw, hee-haw.
But otherwise, pretty good presentation.
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I read that Bigelow were talking about adding a water layer to the inside of their composite habs to increase their BEO radiation tolerance. How effective would a water layer be against GCRs?
I might be wrong, but I'm thinking that solar radiation, if not licked, is at least understood well enough to mitigate the risk to acceptable levels. GCRs are a different matter as no-one has really had the cause to look seriously at the issue yet. I'm hoping that I misunderstood the presentation and that NASA isn't seriously thinking of tap-dancing around the problem by using astronauts old enough that the exposure isn't likely to increase their statistical likelihood of cancer. That's the worst kind of pretending to deal with a problem without actually doing so.
I'm thinking that any eventual physical solution will be a kind of multi-layer sandwich using polyethylene and water as an easy-to-use low-maintenance hydrogen-rich fluid. You might also be able to add that to the water cycling system and let the radiation purify the water (if not ionise it :P ). Even so, we are probably looking at a 20-inch or more hull thickness. Add a separate sun-shield for solar radiation and a storm shelter for solar radiation spikes. That's going to be bulky, so something SLS-class or FH-class with a wide-body PLF is sounding necessary, as is EOR Assembly.
Non-physical solutions must be dependent on developing a mag field generator where the inside the diameter of the generator ring, the mag flux isn't significantly different. It will probably also require flying with a nuclear power pile. Once again, the ol' brain might be playing tricks but I seem to remember reading about someone claiming to have done the no flux inside the torus trick.
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I'm hoping that I misunderstood the presentation and that NASA isn't seriously thinking of tap-dancing around the problem by using astronauts old enough that the exposure isn't likely to increase their statistical likelihood of cancer.
Sounds like the makings of a good sci-fi story. Imagine if NASA actually did that and it backfired; the GCR didn't diminish their lifespan but instead hardened it so that the astronauts became all but immortal! Imagine the civilian pressure to get people into space for "hardening"! What a story that would make! :)
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I read that Bigelow were talking about adding a water layer to the inside of their composite habs to increase their BEO radiation tolerance. How effective would a water layer be against GCRs?
I might be wrong, but I'm thinking that solar radiation, if not licked, is at least understood well enough to mitigate the risk to acceptable levels. GCRs are a different matter as no-one has really had the cause to look seriously at the issue yet. I'm hoping that I misunderstood the presentation and that NASA isn't seriously thinking of tap-dancing around the problem by using astronauts old enough that the exposure isn't likely to increase their statistical likelihood of cancer. That's the worst kind of pretending to deal with a problem without actually doing so.
I'm thinking that any eventual physical solution will be a kind of multi-layer sandwich using polyethylene and water as an easy-to-use low-maintenance hydrogen-rich fluid. You might also be able to add that to the water cycling system and let the radiation purify the water (if not ionise it :P ). Even so, we are probably looking at a 20-inch or more hull thickness. Add a separate sun-shield for solar radiation and a storm shelter for solar radiation spikes. That's going to be bulky, so something SLS-class or FH-class with a wide-body PLF is sounding necessary, as is EOR Assembly.
Non-physical solutions must be dependent on developing a mag field generator where the inside the diameter of the generator ring, the mag flux isn't significantly different. It will probably also require flying with a nuclear power pile. Once again, the ol' brain might be playing tricks but I seem to remember reading about someone claiming to have done the no flux inside the torus trick.
Water is one of the best radiation shielding materials you can get if you can afford the mass.
As for mitigating the huge magnetic fields with a mag shield you can add a second coil to neutralize most but not all of the magnetic field inside the habitat.
There really is not much research on the affects of exposure to large magnetic fields for long duration.
A third option might be an electrostatic shield.
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I'm hoping that I misunderstood the presentation and that NASA isn't seriously thinking of tap-dancing around the problem by using astronauts old enough that the exposure isn't likely to increase their statistical likelihood of cancer.
Sounds like the makings of a good sci-fi story. Imagine if NASA actually did that and it backfired; the GCR didn't diminish their lifespan but instead hardened it so that the astronauts became all but immortal! Imagine the civilian pressure to get people into space for "hardening"! What a story that would make! :)
Didn't something similar happen to 'The Fantastic Four?' ;) But to dent my analogy - they were young Astronaut/Scientists.
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Sounds like the makings of a good sci-fi story. Imagine if NASA actually did that and it backfired; the GCR didn't diminish their lifespan but instead hardened it so that the astronauts became all but immortal! Imagine the civilian pressure to get people into space for "hardening"! What a story that would make! :)
A very interesting thought experiment. My own have trended more towards the question of the effects on our current view of spaceflight (and specifically exploration) if/when productive human lifetimes are extended...
Say your nominal or productive working life is extended to 100-200 years? How would that change our view, approach or strategy to space exploration, colonization (e.g., becoming a "space-faring species"), etc.
Seriosly OT, but I've often thought that advances in the biological and medical sciences may have a far more profound long term effect on our space exploration strategy than advanced propulsion systems, BFR's, etc.
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I'm thinking that any eventual physical solution will be a kind of multi-layer sandwich using polyethylene and water as an easy-to-use low-maintenance hydrogen-rich fluid.
Water is one of the best radiation shielding materials you can get if you can afford the mass.
A third option might be an electrostatic shield.
After viewing that presentation, I kept coming back to another brute force electrostatic solution, expensive but great in the long term:
1. Plonk mass driver on lunar surface.
2. Fire compacted regolith to where it's needed for shielding, raw material.
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I read that Bigelow were talking about adding a water layer to the inside of their composite habs to increase their BEO radiation tolerance. How effective would a water layer be against GCRs?
Water is one of the best radiation shielding materials you can get if you can afford the mass.
Water is good, but you still need a lot of it. Too much in my opinion for such a brute force approach to be used, hundreds of tonnes to shield a small hab. Unlike a relatively small storm shelter against solar storms, GCRs are constant so you need to shield the entire volume they will be living in.
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That's what I was thinking though. It strikes me that the NASA approach is partly hobbled by their seeming need to use ISS-legacy architecture. Maybe the right direction is another one - to build a far larger single hab module with internal divisions. Optimise the hab against GCRs and then include a fixed single-axis shield for increased solar protection.
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That's what I was thinking though. It strikes me that the NASA approach is partly hobbled by their seeming need to use ISS-legacy architecture. Maybe the right direction is another one - to build a far larger single hab module with internal divisions. Optimise the hab against GCRs and then include a fixed single-axis shield for increased solar protection.
Launching a larger single module instead of smaller pieces to make the larger one?
If we already had a HLV that could launch it, then I would say that would most likely be a good direction to go in. However we do not yet have such a launcher. So best to keep the habitable part in segments to be able to use the launchers that we do have. A flexible plan, if we don't get the HLV then we use multiple launches and still get a mission. If we do get the HLV then we could use less launches ( mainly for the propellent ). The smaller pieces also enable global launch capability. The solar power could come from one nation, the crew hab another, and the propulsion even from another nation or commercial investor in the mission(s).
From the looks of the DSH it could be possible to launch the 500 day version in two launches and add some of the internal components once in space by other launches. Water for the radiation shield for example.
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I read that Bigelow were talking about adding a water layer to the inside of their composite habs to increase their BEO radiation tolerance. How effective would a water layer be against GCRs?
Water is one of the best radiation shielding materials you can get if you can afford the mass.
Water is good, but you still need a lot of it. Too much in my opinion for such a brute force approach to be used, hundreds of tonnes to shield a small hab. Unlike a relatively small storm shelter against solar storms, GCRs are constant so you need to shield the entire volume they will be living in.
No, you don't.
GCRs are over Emphasized. The risk for the astronaut is lower than the launch and other parts of the mission. GCR'S risk to the mission itself is practically nil.
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I read that Bigelow were talking about adding a water layer to the inside of their composite habs to increase their BEO radiation tolerance. How effective would a water layer be against GCRs?
Water is one of the best radiation shielding materials you can get if you can afford the mass.
Water is good, but you still need a lot of it. Too much in my opinion for such a brute force approach to be used, hundreds of tonnes to shield a small hab. Unlike a relatively small storm shelter against solar storms, GCRs are constant so you need to shield the entire volume they will be living in.
No, you don't.
GCRs are over Emphasized. The risk for the astronaut is lower than the launch and other parts of the mission. GCR'S risk to the mission itself is practically nil.
I answered the question: How effective would a water layer be against GCRs?
Whether you need shielding depends on many factors the chief ones being mission duration and how many excess cancer deaths do you tolerate.
Taking all cancer risk factors into account (not just radiation) my guess (and it is just a guess because no one has done the research) is that for traditional DRM 5 type missions over 10 years there would be one excess astronaut death due to cancer.
Whether that excess death is acceptable or not is a matter for debate.
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That's what I was thinking though. It strikes me that the NASA approach is partly hobbled by their seeming need to use ISS-legacy architecture. Maybe the right direction is another one - to build a far larger single hab module with internal divisions. Optimise the hab against GCRs and then include a fixed single-axis shield for increased solar protection.
Launching a larger single module instead of smaller pieces to make the larger one?
Yes. Remember that larger module =/= larger launcher, thanks to inflatable hab modules that can be launched on much smaller vehicles. The ISS legacy that I was specifically referring to was the rigid 'coke can' concept. I'm not sure that this is the right way to go and might only be an attempt to save money but may, in the end, just end up compromising mission capability and crew safety.
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I read that Bigelow were talking about adding a water layer to the inside of their composite habs to increase their BEO radiation tolerance. How effective would a water layer be against GCRs?
Water is one of the best radiation shielding materials you can get if you can afford the mass.
Water is good, but you still need a lot of it. Too much in my opinion for such a brute force approach to be used, hundreds of tonnes to shield a small hab. Unlike a relatively small storm shelter against solar storms, GCRs are constant so you need to shield the entire volume they will be living in.
No, you don't.
GCRs are over Emphasized. The risk for the astronaut is lower than the launch and other parts of the mission. GCR'S risk to the mission itself is practically nil.
You know, your statement is actually correct. GCR's do their harmful work no fast enough to be a mission risk during the mission itself. But what do you think the fall-out will be (not just for NASA) when the astronauts, after having succesfully completed their BEO mission, die in the years afterwards from GCR induced cancer? There will be all hell to pay, particularly in the risk-adverse society we live in today.
The fact that NASA is studying these problems now, and identifying them for what they are (the sound barrier to break before really longterm exploration missions can take place) is a good thing. And should not be down-played by anyone.
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You're over emphasizing the risk of cancer. Considering the very few number of astronauts likely to go on such a mission, I'm not even sure the increase in cancer risk is statistically significant (!). Getting cancer would not at all be a sure thing as you imply.
People WILL die in the future from spaceflight, the question is whether they will go anywhere first. It isn't a sure thing that they will get cancer from it. And, as I mentioned, there are other countermeasures. but if we don't go, it is guaranteed they'll never get to Mars.
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It isn't a sound barrier. People need to stop talking about it as a kind of firm, physical barrier which it is not. We will never actually improve it if we don't hold the risk in the proper perspective.
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It isn't a sound barrier. People need to stop talking about it as a kind of firm, physical barrier which it is not. We will never actually improve it if we don't hold the risk in the proper perspective.
I think the statement in the NASA document is clear enough in itself. The sound barrier was broken in 1947. The referral to sound barrier clearly indicates that the authors do NOT think that the barrier raised by GCR is unbreakable. In other words: that barrier is a hurdle to take, like there are many other hurdles on the road to true manned interplanetary exploration.
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You're over emphasizing the risk of cancer. Considering the very few number of astronauts likely to go on such a mission, I'm not even sure the increase in cancer risk is statistically significant (!). Getting cancer would not at all be a sure thing as you imply.
Being statistically significant does not matter. Remember the fall-out of Challenger and Columbia? 14 Lives lost in accidents that could have been prevented. Their deaths were not statistically significant either considering how many people are killed in accidents that were perfectly preventable.
Yet both tragedies very nearly killed the shuttle program, because they were very public deaths.
Granted, astronauts dying of GCR induced cancer years after their mission will not be half as public, yet they will invoke the same emotion within the general public: "Why NASA, did you not prevent this while you could?"
It is for that reason that the risk of GCR is being investigated right now.
People WILL die in the future from spaceflight, the question is whether they will go anywhere first. It isn't a sure thing that they will get cancer from it. And, as I mentioned, there are other countermeasures. but if we don't go, it is guaranteed they'll never get to Mars.
Correct. So, there is your trade-off. Do we got to Mars later, after having taken all appropriate measures to safeguard the astronauts? Or, do we go to Mars earlier and risk losing people afterwards to something that could have been prevented?
With the risk-adverse society we have today I know what the answer will be. We go later.
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It's still over-played. People keep making un-quantified assumptions about the risk, and this adds a sort of dark cloud of foreboding to everything about the topic. We need to use quantified estimates of the risk. For instance, the radiation level on much of the surface of Mars is lower than at ISS, yet we still go to ISS.
There's another elephant in the room: the estimates of cancer risk are extrapolated from extreme, acute radiation events like nuclear explosions, where the body has no time to repair itself (or increase its defenses) before getting more damage. We make this assumption because it is the conservative one.
In fact, it seems like every step along the way, we make the conservative assumption. This adds up to hugely over-emphasizing a risk which doesn't even threaten the success of the mission at all (!) while thus distracting resources from the much greater risks, such as launch failure, landing, ascent, docking, reentry, etc.
The astronauts need to know the risks and accept or reject them. Do we outlaw smoking for federal employees?
Look, if we shield against the vast majority of solar radiation (doable) and send the astronauts during solar max (when GCRs are half as much) and land on low-altitude parts of the surface where the GCR flux is already less than ISS and then partially shield the habs with Martian regolith, then this really isn't a situation where cancer is inevitable like you keep making it out to be. In fact, the risk is supposedly linear, so by this logic, we shouldn't even be launching astronauts to ISS, should we? And yet we are.
If we wait until we remove any kind of risk like this, we literally will never go.
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If we wait until we remove any kind of risk like this, we literally will never go.
I agree that full shielding isn't possible. However, that doesn't remove the responsibility to make reasonable mitigation efforts to reduce the dosage received during any flight period - remember, it may not be possible to arrange interplanetary flights around solar maximum or minimum due to their duration.
One of the things in "A Case For Mars" that set my teeth on edge was Zubrin's attempt to hand-wave away the radiation issue by suggesting it was more a moral failing of lack of courage. There is a hazard; let's at least make an attempt to address it in such a way that reduces the risk, even if it isn't possible to get it all the way down.
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If we wait until we remove any kind of risk like this, we literally will never go.
I agree that full shielding isn't possible. However, that doesn't remove the responsibility to make reasonable mitigation efforts to reduce the dosage received during any flight period - remember, it may not be possible to arrange interplanetary flights around solar maximum or minimum due to their duration.
One of the things in "A Case For Mars" that set my teeth on edge was Zubrin's attempt to hand-wave away the radiation issue by suggesting it was more a moral failing of lack of courage. There is a hazard; let's at least make an attempt to address it in such a way that reduces the risk, even if it isn't possible to get it all the way down.
Well, he's basically right.
But we can reasonably shield against solar radiation, which accounts for at least half and actually can jeopardize the mission.
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If we wait until we remove any kind of risk like this, we literally will never go.
One of the things in "A Case For Mars" that set my teeth on edge was Zubrin's attempt to hand-wave away the radiation issue by suggesting it was more a moral failing of lack of courage. There is a hazard; let's at least make an attempt to address it in such a way that reduces the risk, even if it isn't possible to get it all the way down.
Well, he's basically right.
And it is there that we seriously differ.
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If we wait until we remove any kind of risk like this, we literally will never go.
One of the things in "A Case For Mars" that set my teeth on edge was Zubrin's attempt to hand-wave away the radiation issue by suggesting it was more a moral failing of lack of courage. There is a hazard; let's at least make an attempt to address it in such a way that reduces the risk, even if it isn't possible to get it all the way down.
Well, he's basically right.
And it is there that we seriously differ.
How so? We won't think twice about spending a few extra billion to slightly reduce an astronaut's risk of cancer, but couldn't that few billion, if spent on Earth for preventative measures and/or screening, reduce the risk for hundreds of thousands of people? Heck, I bet that several billion spent on aggressive measures to reduce smoking could reduce the cancer risk for a million people by more than the risk of cancer that the astronaut would face.
To not go just because of a risk of cancer not exceeding that of smoking is, indeed, a moral failure, IMHO.
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This might be getting off-topic, but I agree completely. Some folks want to basically scuttle all manned spaceflight because of radiation concerns that might not even exist. Until we actually go, we have absolutely no real, scientific data about the long-term effects of GCR on the human body in space. It's possible that the human body is perfectly capable of repairing the slow, chronic cellular damage that GCR causes; we don't really know. Even if the pessimistic view ends up being correct, it's still just a low risk - not a death sentence. There's also a low risk of dying from space junk, micrometeorite strike, launch vehicle failure, heat shield failure, and computer error. We can't eliminate these risks - so why should we insist of eliminating radiation risks, especially when we don't have enough actual long-term exposure data to be making intelligent decisions about it.
Airline pilots and staff have higher exposure to GCR's as well. It's part of the job. So do people living in the Andes (GCR exposure doubles with every 2,000 feet of altitude above sea level). We shouldn't demand that airplanes be surrounded by a shell of water a meter thick, or that people who live at high elevations be forcibly relocated to the lowlands. Hell, mountain climbers are getting bombarded like crazy, but they accept the risks. I think the radiation hysteria is very damaging to progress in human spaceflight. It would be nice if a member of the astronaut core just stood up and said "We're not afraid of GCR. Bring it on." Because the more GCR exposure our astronauts get, the better we'll understand the danger, if a serious danger exists at all. Just like all scientific work with regard to health risks, there is uncertainty. Shielding astronauts from GCRs means no progress will be made in understanding GCR damage. Honestly, it's like people want to cure malaria without having any malaria patients to study.
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This might be getting off-topic, but I agree completely. Some folks want to basically scuttle all manned spaceflight because of radiation concerns that might not even exist. Until we actually go, we have absolutely no real, scientific data about the long-term effects of GCR on the human body in space. It's possible that the human body is perfectly capable of repairing the slow, chronic cellular damage that GCR causes; we don't really know. Even if the pessimistic view ends up being correct, it's still just a low risk - not a death sentence. There's also a low risk of dying from space junk, micrometeorite strike, launch vehicle failure, heat shield failure, and computer error. We can't eliminate these risks - so why should we insist of eliminating radiation risks, especially when we don't have enough actual long-term exposure data to be making intelligent decisions about it.
Airline pilots and staff have higher exposure to GCR's as well. It's part of the job. So do people living in the Andes (GCR exposure doubles with every 2,000 feet of altitude above sea level). We shouldn't demand that airplanes be surrounded by a shell of water a meter thick, or that people who live at high elevations be forcibly relocated to the lowlands. Hell, mountain climbers are getting bombarded like crazy, but they accept the risks. I think the radiation hysteria is very damaging to progress in human spaceflight. It would be nice if a member of the astronaut core just stood up and said "We're not afraid of GCR. Bring it on." Because the more GCR exposure our astronauts get, the better we'll understand the danger, if a serious danger exists at all. Just like all scientific work with regard to health risks, there is uncertainty. Shielding astronauts from GCRs means no progress will be made in understanding GCR damage. Honestly, it's like people want to cure malaria without having any malaria patients to study.
On-orbit measurements and studies into the effects of radiation and particle exposure (for SPE, GCR and HZE) have been on-going since the days of Skylab, thru multiple missions of Salyut and Mir and are continued on ISS today. Those studies are the very reason why lifetime dosage limits have been imposed in the first place. Since the exact effects of prolonged exposure remain somewhat unknown, the limits have been imposed to stay on the safe side.
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I'm hoping that I misunderstood the presentation and that NASA isn't seriously thinking of tap-dancing around the problem by using astronauts old enough that the exposure isn't likely to increase their statistical likelihood of cancer.
Personally I like it:)
I totally expect RobotBeat is right, but this is another perfectly valid solution if there is any doubt in the short term.
It would still be nice to reduce the problem to the point where it is safe even for generations of families living and working in space but that hardly urgent. Let research continue at a natural pace.
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It's still over-played. People keep making un-quantified assumptions about the risk, and this adds a sort of dark cloud of foreboding to everything about the topic. We need to use quantified estimates of the risk.
The astronauts need to know the risks and accept or reject them.
If we wait until we remove any kind of risk like this, we literally will never go.
Actually, crew will be sent to L2 and to the lunar surface, and beyond L2.
At no point did anyone state that NASA will never go anywhere. it just seems like it.
Is this a rather poor attempt at FUD to support lunar only missions and nothing else?
As proof, DSH has almost ZERO GCR protection and it plans to go somewhere. Orion to L2 in 2021 for four days and almost Zero GCR protection! Constellation and 6 day lunar sorties and almost zero GCR protection.
IOW: think very short term missions in terms of days.
But when you think in these terms, one asks, why send the crew at all?
Why not add in a really critical scientific objective? 8)
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What will happen is this: NASA will define the risk to be 3% risk of developing cancer with 95 percent certainty (or fill in the the correct values), and when any crew member reaches this threshold, their career is OVER. Some have suggested that waivers be included in the process.
The more protection that is added, or the higher acceptable risk is accommodated, then the less number of crew is needed, or vice versa, for a given set of missions. So the first spinoff is that by including protection, a reduction in training needs is possible over the long term.
One thing however is quite clear: the length of the trip to Mars or even to an asteroid and back is not possible without substantial increases in risk and age (back to the grumpy old men crew with a waiver). it will be interesting to see how this plays out, hopefully on a new thread!
Go back to lunar sorties, or live like moles on the lunar surface underwater or under regolith, or start working on GCR protection that will have GUARANTEED spinoffs back to earth. Quite a challenging, rewarding, and critical program :)
The choice is .... oops almost said 'yours'.....the Congressional Design Teams' (CDTs).
Oh well...back to checking the status of 4 new engine development programs, abundant chemical (http://forum.nasaspaceflight.com/index.php?topic=30039.msg979974#msg979974) and the oxymoronic HLV depot centric architecture (http://forum.nasaspaceflight.com/index.php?topic=30357.msg979846#msg979846).....
This approach however, just seems so much more strategic:
The L2 Gateway in essence provides a long term critical science goal to economically develop GCR protection strategies, increases flight rates, and provides guaranteed spinoffs back to earth with the flexible option of proceeding with other missions and technology challenges once solutions are found and demonstrated. It is most certainly not a destination, only a critical stepping stone. (http://forum.nasaspaceflight.com/index.php?topic=1337.msg979399#msg979399)