MSL FAQ - The pool of questions |
MSL FAQ - The pool of questions |
 Jun 1 2007, 03:11 PM
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Founder  Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1  |
Rob Manning and I swopped emails last night - and we think it might make sense to pool all the questions people have about MSL (and specifically MSL's EDL ) into one thread - and then answer as many as make sense either via a Q'n'A in the style of the previous ones I've done with Steve and Jim - or via Rob's typing fingers.
It'll be a few weeks till we sort this out - but submit-away until then  Doug |
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Jun 4 2007, 05:22 PM
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#2
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 Administrator Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 |
Here's a few that I've received by email. The first two are variations on a theme:
What kind of AI, if any, is built into the descent stage in terms of selecting an exact point to set the rover down? In other words, does the sky crane "look around" for a suitable spot as it descends, or does it just go straight down regardless? Is it the rover or the descent stage that decides when the rover is safe on the ground? I'm guessing they both need to know when touch-down occurs because, from the video, it looks like the rover releases the cables and the descent stage flies clear of the rover. So do they both detect it? Or does one detect it and communicate to the other? How is detection done? Radar? Touch sensor? Why is the "skycrane" concept better than just lowering the rover to the ground with retrorockets (as if using zero-length cables)? Are the cables used for cushioning? Wouldn't it be better for the "skycrane" to hover in one place and lower the rover by unwinding the cables very slowly till the rover touches down, rather than descending with the cables fully extended, as in the video? -------------------- My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
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Jun 4 2007, 10:30 PM
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#3
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 Member Group: Members Posts: 321 Joined: 6-April 06 From: Cape Canaveral Member No.: 734 |
QUOTE (elakdawalla @ Jun 4 2007, 01:22 PM)  1. Why is the "skycrane" concept better than just lowering the rover to the ground with retrorockets (as if using zero-length cables)? Are the cables used for cushioning? Wouldn't it be better for the "skycrane" to hover in one place and lower the rover by unwinding the cables very slowly till the rover touches down, rather than descending with the cables fully extended, as in the video? Skycrane concept eliminates thruster plumes and dust on the rover The mobility system (wheels etc) absorb the shock no, extended hover is harder to maintain |
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Jun 5 2007, 01:44 PM
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#4
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Member Group: Members Posts: 153 Joined: 11-December 04 Member No.: 120 |
QUOTE (Jim from NSF.com @ Jun 4 2007, 10:30 PM) Skycrane concept eliminates thruster plumes and dust on the rover Would that be a problem when there is no solar panel up there? I believe the big advantage of the skycrane is that it minimizes the mass that actually lands. And by doing so it reduces the stress and loads caused by touchdown. QUOTE (Jim from NSF.com @ Jun 4 2007, 10:30 PM) The mobility system (wheels etc) absorb the shock I don't think a rocker-bogie system does much shock absorbing as it is completely rigid. This simply means the vertical speed at touch down must be very small. BTW, I'm much more concerned about horizontal speed at landing than about vertical speed, which is much more easy to control. I'm afraid the suspension system will not have much tolerance for horizontal speed at touchdown and any swinging motion of the rover must be dampened by the skycrane. Or does the rover have any reaction control system of its own? (I don't think so, as it doesn't carry any fuel tanks). This will be a pretty tough control job in the windy Martian atmosphere and coming from a huge horizontal entry speed. |
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Jun 5 2007, 04:31 PM
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#5
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Member Group: Members Posts: 321 Joined: 6-April 06 From: Cape Canaveral Member No.: 734 |
QUOTE (Cugel @ Jun 5 2007, 09:44 AM) Would that be a problem when there is no solar panel up there? I believe the big advantage of the skycrane is that it minimizes the mass that actually lands. And by doing so it reduces the stress and loads caused by touchdown. I don't think a rocker-bogie system does much shock absorbing as it is completely rigid. This simply means the vertical speed at touch down must be very small. BTW, I'm much more concerned about horizontal speed at landing than about vertical speed, which is much more easy to control. I'm afraid the suspension system will not have much tolerance for horizontal speed at touchdown and any swinging motion of the rover must be dampened by the skycrane. Or does the rover have any reaction control system of its own? (I don't think so, as it doesn't carry any fuel tanks). This will be a pretty tough control job in the windy Martian atmosphere and coming from a huge horizontal entry speed. The dust and the effluents from the thrusters would contaminate the rover there is no "huge" horizontal velocity, it is coming vertical by the time the rover is repelling |
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Jun 5 2007, 05:02 PM
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#6
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Member Group: Members Posts: 153 Joined: 11-December 04 Member No.: 120 |
QUOTE (Jim from NSF.com @ Jun 5 2007, 04:31 PM) there is no "huge" horizontal velocity, it is coming vertical by the time the rover is repelling I stand corrected on that one. |
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djellison MSL FAQ - The pool of questions Jun 1 2007, 03:11 PM
elakdawalla Doug and I had the same idea -- he got to Rob firs... Jun 1 2007, 05:11 PM Juramike My Big list 'o Questions:
1) How scalable is ... Jun 1 2007, 06:03 PM akuo Ok, here is my question:
MSL is not limited by el... Jun 1 2007, 07:43 PM
Jim from NSF.com QUOTE (akuo @ Jun 1 2007, 03:43 PM) Ok, h... Jun 1 2007, 09:16 PM centsworth_II QUOTE (Jim from NSF.com @ Jun 1 2007, 05... Jun 4 2007, 02:45 PM Jim from NSF.com QUOTE (centsworth_II @ Jun 4 2007, 10:45 ... Jun 4 2007, 07:45 PM Stu Apart from the obvious question that springs to mi... Jun 1 2007, 09:17 PM mcaplinger QUOTE (Stu @ Jun 1 2007, 02:17 PM) Will w... Jun 2 2007, 07:06 PM djellison QUOTE (djellison @ Jun 1 2007, 04:11 PM) ... Jun 1 2007, 09:45 PM Stu QUOTE (djellison @ Jun 1 2007, 10:45 PM) ... Jun 2 2007, 05:14 AM nprev Okay, I got two:
1. How exactly is the MSL/crane ... Jun 1 2007, 11:35 PM dvandorn And here's a few more to add to nprev's:
... Jun 2 2007, 12:45 AM Toma B Thanks Doug!
Here are my questions:
a ) Tests... Jun 2 2007, 06:43 AM Eluchil Here are a few Rob might know the answers to:
1) ... Jun 2 2007, 06:46 AM djellison There's a few questions that I think I can do ... Jun 2 2007, 07:53 AM helvick I presume you mean MSL2MRO there. Jun 2 2007, 09:16 AM djellison Yeah - that what I said.
Cough ahem oops well... Jun 2 2007, 09:39 AM DEChengst Looking at it from an artistic point of view:
Is ... Jun 2 2007, 02:07 PM djellison QUOTE (DEChengst @ Jun 2 2007, 03:07 PM) ... Jun 2 2007, 03:07 PM nprev QUOTE (DEChengst @ Jun 2 2007, 07:07 AM) ... Jun 2 2007, 04:30 PM ElkGroveDan Once science is well on the way, are there any pla... Jun 2 2007, 03:05 PM djellison This skycrane/decent stage debate is ending. Now. ... Jun 2 2007, 06:46 PM Sunspot Malin Space Science Systems has information on som... Jun 2 2007, 07:16 PM djellison Here's one for you Mike - I get bayer filters ... Jun 2 2007, 07:18 PM mcaplinger QUOTE (djellison @ Jun 2 2007, 12:18 PM) ... Jun 2 2007, 08:13 PM nprev Nice, you guys; sounds like some exciting pics are... Jun 2 2007, 07:24 PM Jim from NSF.com The amount of fuel in the DESCENT STAGE should be ... Jun 2 2007, 07:32 PM nprev Ah. So, then, the descent stage is expected to sta... Jun 2 2007, 07:48 PM Jim from NSF.com Not really, the flyout is independent of landing s... Jun 2 2007, 07:51 PM nprev I see; thanks! I was wondering about some of t... Jun 2 2007, 07:56 PM djellison Ahh - suddenly it all becomes clear(er) - cheers ... Jun 2 2007, 08:49 PM climber Question for both Phoenix and MSL : what kind of c... Jun 2 2007, 09:21 PM mcaplinger QUOTE (climber @ Jun 2 2007, 02:21 PM) Qu... Jun 2 2007, 10:00 PM monitorlizard Given the power output of MSL's RTG and the be... Jun 2 2007, 11:57 PM Thu I have some questions:
1. What is the ratio of fi... Jun 4 2007, 01:18 AM mcaplinger QUOTE (Thu @ Jun 3 2007, 06:18 PM) 2. I r... Jun 4 2007, 02:53 AM Pertinax QUOTE (mcaplinger @ Jun 3 2007, 10:53 PM)... Jun 5 2007, 07:34 PM mcaplinger QUOTE (Pertinax @ Jun 5 2007, 12:34 PM) I... Jun 6 2007, 02:07 AM remcook If you've got an RTG you might as well do nigh... Jun 4 2007, 08:44 AM tty QUOTE (Cugel @ Jun 5 2007, 03:44 PM) Woul... Jun 5 2007, 04:31 PM Alex Chapman I know it’s a little off topic but I have a quick ... Jun 5 2007, 07:37 AM Jim from NSF.com SAM is being redesigned at the moment Jun 5 2007, 11:45 AM centsworth_II Hold a Yo Yo by the string. With a few cm of stri... Jun 5 2007, 03:14 PM Pertinax Thank you.
I didn't know if there were an... Jun 6 2007, 01:21 PM MarsEngineer Holy smokes! I leave you folks for a few days ... Jun 7 2007, 12:08 AM nprev Hey, Rob! Thanks for the update. (Surprising h... Jun 7 2007, 04:26 AM Jim from NSF.com There are some "major" changes to the s... Jun 7 2007, 05:16 AM Geographer Why not have two rovers like MER? Double the scie... Jun 20 2007, 07:16 AM djellison Because the money isn't there to do it. MER w... Jun 20 2007, 07:26 AM Toma B I'm just curious ,how much would MER cost now ... Jun 20 2007, 07:51 AM Jim from NSF.com B)-->QUOTE(Toma B @ Jun 20 2007, 03:51 AM... Jun 22 2007, 02:32 AM nprev QUOTE The launch vehicle would have to be differen... Jun 22 2007, 02:54 AM AlexBlackwell QUOTE (Jim from NSF.com @ Jun 21 2007, 04... Jun 22 2007, 05:21 PM djellison Well - when I spoke to Squyres back in the autumn ... Jun 20 2007, 08:32 AM Oren Iishi QUOTE (djellison @ Jun 20 2007, 08:32 AM)... Jun 28 2007, 11:37 PM dvandorn I will also point out, in regards re-using the MER... Jun 20 2007, 12:56 PM Geographer Thanks djellison, I had no idea MSL is costing tha... Jun 21 2007, 09:53 AM helvick An RTG of the type MSL will use costs in the regio... Jun 21 2007, 10:50 AM Jim from NSF.com QUOTE (helvick @ Jun 21 2007, 06:50 AM) A... Jun 22 2007, 02:35 AM Jim from NSF.com The vehicles weren't design for that. Per Pet... Jun 22 2007, 07:20 PM AlexBlackwell I know MER wasn't designed for that; the assum... Jun 22 2007, 07:28 PM hendric Rob,
How is MSL going to keep the sand out of it... Jun 23 2007, 10:44 PM MarsEngineer QUOTE (hendric @ Jun 23 2007, 03:44 PM) R... Jul 2 2007, 04:02 AM PhilHorzempa Rob,
There is a thread here at UMSF discussi... Jun 28 2007, 12:43 AM Jim from NSF.com QUOTE (PhilHorzempa @ Jun 27 2007, 08:43 ... Jun 28 2007, 02:38 AM ElkGroveDan QUOTE (Jim from NSF.com @ Jun 27 2007, 06... Jun 29 2007, 04:17 AM mcaplinger QUOTE (PhilHorzempa @ Jun 27 2007, 05:43 ... Jun 28 2007, 06:48 PM Jim from NSF.com QUOTE (mcaplinger @ Jun 28 2007, 02:48 PM... Jun 28 2007, 08:08 PM gallen_53 QUOTE (mcaplinger @ Jun 28 2007, 06:48 PM... Jun 29 2007, 11:43 PM MarsEngineer QUOTE (mcaplinger @ Jun 28 2007, 11:48 AM... Jul 2 2007, 04:32 AM David QUOTE (MarsEngineer @ Jul 2 2007, 04:32 A... Jul 2 2007, 12:06 PM Jim from NSF.com QUOTE (David @ Jul 2 2007, 08:06 AM) The ... Jul 8 2007, 12:33 PM climber QUOTE (MarsEngineer @ Jul 2 2007, 06:32 A... Jul 8 2007, 10:46 AM Stephen QUOTE (mcaplinger @ Jun 29 2007, 04:48 AM... Jul 11 2007, 10:12 AM dvandorn QUOTE (Stephen @ Jul 11 2007, 05:12 AM) ... Jul 13 2007, 01:07 AM Jim from NSF.com Because it has be used over and over in the Mars y... Jun 29 2007, 01:32 AM Jim from NSF.com Because the Admin has the final say.
As for burea... Jun 29 2007, 03:11 PM djellison Oh - I heard other names got used once or twice gi... Jun 29 2007, 11:47 PM mchan Those got mentioned here. Divorce was one, can... Jun 30 2007, 01:55 AM Toma B I'm little impatient...
When is "Rob Mann... Jul 11 2007, 10:20 AM djellison Plan is for me to pull all the questions together ... Jul 11 2007, 10:43 AM lyford All that MARDI talk over on the Phoenix thread got... Jul 13 2007, 11:51 PM monitorlizard Some may feel this belongs in the Mars Sample Retu... Jul 14 2007, 08:00 AM Jim from NSF.com Close to launch? CDR just happened and the sample... Jul 14 2007, 01:22 PM nprev Agreed, Monitor. However, that sounds like a poten... Jul 14 2007, 12:39 PM lyford QUOTE (nprev @ Jul 14 2007, 05:39 AM) Of ... Jul 14 2007, 03:07 PM edstrick "...science team would have to be pretty sele... Jul 15 2007, 07:05 AM nprev QUOTE (edstrick @ Jul 15 2007, 12:05 AM) ... Jul 16 2007, 02:52 AM monitorlizard Instead of "close to launch" I probably ... Jul 15 2007, 10:29 AM monitorlizard The great thing about this forum is that the inter... Jul 15 2007, 10:49 AM Jim from NSF.com As of now, it is going to be a horizontal carousel... Jul 15 2007, 02:07 PM Phil Stooke odoug: "I may be misremembering, but I have t... Jul 15 2007, 06:14 PM edstrick There was a very very good general review of the T... Jul 16 2007, 06:13 AM mchan I do recall reading the Astronautics and Aeronauti... Jul 16 2007, 08:35 AM |
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