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#400
by
jongoff
on 26 Mar, 2015 14:02
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So...what do we know about the material composition of this asteroid?
It appears to be a carbonaceous chondrite.
And it has its own twitter account: @Asteroid2008EV5
~Jon
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#401
by
saliva_sweet
on 26 Mar, 2015 14:14
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My only concern with the boulder option is that I don't see a point to the crew part. Why not just bring the whole thing down to earth?
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#402
by
Moe Grills
on 26 Mar, 2015 14:24
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So...what do we know about the material composition of this asteroid?
You hit the nail on the head.
The answer to your question is? We will find out for sure by either human spaceflight or robotics or both. Science is the key; or have some of you armchair engineers forgot that SCIENCE is a primary goal.
And, oh, those of you griping and bellyaching that the planned mission is not ambitious enough, get a DIFFERENT perspective. The last time humans went beyond LEO was when? December, 1972?
42 years plus.
Some of you weren't even born the last time it happened. Some of you will not be around the next time it happens.
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#403
by
jongoff
on 26 Mar, 2015 14:37
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My only concern with the boulder option is that I don't see a point to the crew part. Why not just bring the whole thing down to earth?
I could think of a few:
1- The thing will likely mass between 40-80 mT. We have no way of landing something that size. It would be a meteorite, which means it likely would break up on reentry.
2- A bunch of chunks of a man-made meteorite scattered over a bunch of miles is a lot less useful for learning how to mine asteroids than said chunk in an accessible orbit--hard to prove out a zero-g process on the ground.
3- Do you seriously think anyone would be cool with us intentionally crashing even a small meteorite into the planet?
You could instead fly it to LEO to visit, but that would take a lot more propellant (2-3x the mass of the proposed return vehicle, 8-20 tonnes of Xenon), and it would take a crazy long time to spiral in (probably 5 years or more to make it from lunar orbit back to LEO).
You could try aerobraking, but then you'd need a pretty large aerobrake (probably heavier than the asteroid return vehicle again), and high thrust systems for recircularizing so it doesn't turn into a meteor.
No, when you look at the constraints, putting it in a long-term stable, but easy to access lunar orbit makes the most sense of all the alternatives.
~Jon
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#404
by
saliva_sweet
on 26 Mar, 2015 15:06
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I could think of a few:
1- The thing will likely mass between 40-80 mT. We have no way of landing something that size. It would be a meteorite, which means it likely would break up on reentry.
That is the gist of it yes. My point is if you're already picking a boulder it doesn't necessarily need to be that big (4m diameter). A 1 cubic meter boulder if shaped right would fit through the hatch of CST-100. Dragons hatch is bigger and could accomodate a bigger thing still, but weight may become too much. A custom solution with regular 5m heat shield could probably bring down a 2m diameter boulder. Some exotic inflatable heat shields and/or aggressive lithobraking may push it even higher.
edit: spelling
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#405
by
laszlo
on 26 Mar, 2015 15:52
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Option B is even more pointless than the original asteroid in a bag mission. If you want a boulder from an asteroid, just walk across the National Mall from NASA HQ into the Smithsonian and take your pick. Having watched Apollo happen, I don't see how NASA can talk about this mess with a straight face.
Just cancel the stupid thing and use the money for real human exploration.
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#406
by
jongoff
on 26 Mar, 2015 16:06
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Option B is even more pointless than the original asteroid in a bag mission. If you want a boulder from an asteroid, just walk across the National Mall from NASA HQ into the Smithsonian and take your pick. Having watched Apollo happen, I don't see how NASA can talk about this mess with a straight face.
Just cancel the stupid thing and use the money for real human exploration.
This is an all too common, but frustratingly ignorant argument.
Simple fact is that meteorites are not exactly a representative example of asteroid properties, especially when it comes to carbonaceous chondrites. Meteorites you can actually pick up tend to self select for the most structurally sound samples, because the weaker ones by definition burn up on the way in. And having meteors on the ground tell you nothing about how to do zero-g processing, or how the reentry thermal environment has changed the chemical composition of the samples, or what regolith (which also by definition typically gets blown off during reentry) is really like.
We have meteors from Mars and the Moon too. Should we say "good enough, why do we need to go to Mars now since we have samples back here on earth?"
Also, comparing ARM to Apollo is also ridiculous. ARM is just a precursor mission, part of a bigger story. Think more along the lines of Ranger or Gemini. Something that gets us useful exploration, and paves the way for more ambitious future missions. ARM is going to be less than 3% of NASA's HEOMD budget over the next 10 years. Stop acting like it's 97% (and this applies to a ton of other people too).
~Jon
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#407
by
catdlr
on 26 Mar, 2015 16:38
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Asteroid Redirect Mission: Robotic Segment
Published on Mar 26, 2015
This concept animation illustrates the robotic segment of NASA's Asteroid Redirect Mission. The Asteroid Redirect Vehicle, powered by solar electric propulsion, travels to a large asteroid to robotically collect a boulder from its surface. It then conducts a "gravity tractor" planetary defense demonstration on the asteroid before bringing the captured boulder to a stable orbit around the moon where astronauts can visit, explore, and sample it.
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#408
by
zubenelgenubi
on 26 Mar, 2015 18:04
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Option B is even more pointless than the original asteroid in a bag mission. If you want a boulder from an asteroid, just walk across the National Mall from NASA HQ into the Smithsonian and take your pick. Having watched Apollo happen, I don't see how NASA can talk about this mess with a straight face.
Just cancel the stupid thing and use the money for real human exploration.
This is an all too common, but frustratingly ignorant argument.
Simple fact is that meteorites are not exactly a representative example of asteroid properties, especially when it comes to carbonaceous chondrites. Meteorites you can actually pick up tend to self select for the most structurally sound samples, because the weaker ones by definition burn up on the way in. And having meteors on the ground tell you nothing about how to do zero-g processing, or how the reentry thermal environment has changed the chemical composition of the samples, or what regolith (which also by definition typically gets blown off during reentry) is really like.
We have meteors from Mars and the Moon too. Should we say "good enough, why do we need to go to Mars now since we have samples back here on earth?"
Also, comparing ARM to Apollo is also ridiculous. ARM is just a precursor mission, part of a bigger story. Think more along the lines of Ranger or Gemini. Something that gets us useful exploration, and paves the way for more ambitious future missions. ARM is going to be less than 3% of NASA's HEOMD budget over the next 10 years. Stop acting like it's 97% (and this applies to a ton of other people too).
~Jon
I'll add: context, context, CONTEXT.
Forum-gurus correct me if I'm wrong here: Scientists have determined a small fraction of the meteorites collected here on Earth came from the Moon and Mars (and Vesta). No one knows from WHERE on these bodies the meteorites derived. You can't point to a latitude/longitude location on world X and say--"See that crater; this meteorite came from here."
Context was fundamentally important regarding the Apollo lunar samples. It will be fundamentally important regarding Mars Sample Return, and is important now for the mission planning.
Why would this be any different for an asteroid? It isn't.
No context--a fundamental scientific reason for the mission is removed.
My 2 quatloos,
Zubenelgenubi
PS
Jon, thanks for covering the briefing!
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#409
by
newpylong
on 26 Mar, 2015 18:33
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I could think of a few:
1- The thing will likely mass between 40-80 mT. We have no way of landing something that size. It would be a meteorite, which means it likely would break up on reentry.
That is the gist of it yes. My point is if you're already picking a boulder it doesn't necessarily need to be that big (4m diameter). A 1 cubic meter boulder if shaped right would fit through the hatch of CST-100. Dragons hatch is bigger and could accomodate a bigger thing still, but weight may become too much. A custom solution with regular 5m heat shield could probably bring down a 2m diameter boulder. Some exotic inflatable heat shields and/or aggressive lithobraking may push it even higher.
edit: spelling
What does Dragon or CST-100 have to do with anything? The ARM concept has less to do with the rock and more to do with the technologies of getting there and back.
Not saying I support ARM but these are the facts.
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#410
by
AntiAnti
on 26 Mar, 2015 18:48
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Oh. It looks senselessly and strange without a habitat module. So they need cabin depressurization for EVA? Like we're in 1960-s again.
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#411
by
arachnitect
on 26 Mar, 2015 19:01
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Oh. It looks senselessly and strange without a habitat module. So they need cabin depressurization for EVA? Like we're in 1960-s again.
Hab module was discussed at one point. Does anybody know if it's been ruled out completely?
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#412
by
jongoff
on 26 Mar, 2015 19:18
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Oh. It looks senselessly and strange without a habitat module. So they need cabin depressurization for EVA? Like we're in 1960-s again.
Hab module was discussed at one point. Does anybody know if it's been ruled out completely?
I don't think it has been ruled out at all. It may not be part of the baseline, but the mission is just barely moving into Phase A.
~Jon
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#413
by
TrevorMonty
on 26 Mar, 2015 19:28
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Cygnus and Exoliner are possible options for a habitat. Given LM built Orion converting the Exoliner into companion habitat should be reasonably straightforward.
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#414
by
saliva_sweet
on 26 Mar, 2015 20:10
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The ARM concept has less to do with the rock and more to do with the technologies of getting there and back.
Then forget the rock. It's just that I was looking at the video catldr posted and it looked really great until three minute mark when a guy with a pickaxe and a suitcase showed up in a huge rocket. The two missions should be split. Each part is making the other one worse.
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#415
by
arachnitect
on 26 Mar, 2015 20:44
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The ARM concept has less to do with the rock and more to do with the technologies of getting there and back.
Then forget the rock. It's just that I was looking at the video catldr posted and it looked really great until three minute mark when a guy with a pickaxe and a suitcase showed up in a huge rocket. The two missions should be split. Each part is making the other one worse.
A while back somebody from NASA basically said that the two missions were worth doing even if the rock and the astronauts don't end up in the same place at the same time, so be careful what you wish for.
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#416
by
A_M_Swallow
on 27 Mar, 2015 01:36
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The ARM concept has less to do with the rock and more to do with the technologies of getting there and back.
Then forget the rock. It's just that I was looking at the video catldr posted and it looked really great until three minute mark when a guy with a pickaxe and a suitcase showed up in a huge rocket. The two missions should be split. Each part is making the other one worse.
The unmanned Asteroid Retrieval Mission (ARM) to get the bolder and the manned mission to return the sample will be under different US presidents so they will probably be separated.
I suggest that the manned sample collection mission is called LEG - Lobe Examination and Gather.
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#417
by
darkenfast
on 27 Mar, 2015 01:42
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Does anyone think that the voters are really going to buy the idea that this is a worthwhile step on the way to Mars?
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#418
by
RonM
on 27 Mar, 2015 01:53
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Does anyone think that the voters are really going to buy the idea that this is a worthwhile step on the way to Mars?
The voters won't notice. No one other than us enthusiasts pays any attention until there is a launch.
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#419
by
yg1968
on 27 Mar, 2015 01:54
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