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MSL Approach Phase
nprev
post Jun 23 2012, 05:32 PM
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We're now 45 days from landing, so as of 23 Jun please post all comments related to the end of the transit to Mars here.

Go Curiosity!!!!


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A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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MarsEngineer
post Jun 29 2012, 01:11 AM
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Hi again,

Doug is correct (he seems to have the knack, me on the other hand...). There is margin well above 0.8 m/s (I forget the number but it depends a lot on surface characteristics if my memory serves). With these sorts of multi-DOF control systems, either it is coming down well within the spec or ... it won't and something is wildly wrong.

Ironically the Phoenix and Viking landers could not afford to land slower due to dynamics issues with slower velocity (need for leg stroke for touchdown detection, surface-plume interaction, fuel cost, etc). However the velocity knowledge and control accuracy for Viking and Phoenix was fantastic and about the same as MSL's (in fact MSL and Phoenix both use the same inertial measurement unit (IMU) design). Because of the skycrane architecture, MSL is simply able to capitalize on the IMU and on the fact that the decent engines are a long way from the surface and wheels, that the engines are dynamically uncoupled with the rover touchdown event to allow a much slower terminal descent velocity. If we were willing to use more fuel we could probably have reduced the velocity even more, but we did not need to. The big benefit of a slower touchdown is that the rover's wheels (aka "legs") can be used as landing gear plus that slow velocity really broadens the spectrum of Mars surfaces that are considered "safe". (Of course I am wildly biased - opinions expressed are those of the co-co-co-co-inventer and do not reflect NASA/JPL/Caltech).

With "somewhat controlled velocity" landing systems like MER (6 solid rockets) or "nearly controlled velocity" landing systems like Pathfinder (3 solid rockets) the landing system obviously has to be robust to a much wider range of impact velocities (let alone surface characteristics).

You know I can't tell you how much fun it is to come by here (I wish I had more time!!!). I get a huge kick from the thoughtful discussions of risk, and the fun walks through memory lane (like the link that SFJCody left on Post#169 to a 1997 bulletin board about the weirdness of Pathfinder's landing system and even a discussion about my old web page on EDL I created back then - what a hoot!)

In my opinion, all of these missions (especially the ones that have to land safely on Mars) are experimental vehicles and have a rather substantial element of risk. For all of the Mars lander missions I have worked on (MPF, MER, PHX and MSL) like everyone else, I am initially daunted by the vast array of all the "things that must go right". The mountain ahead seems insurmountable. But then I (we) look down at my (our) feet and move myself one step at a time, one minute detail at a time, oftentimes with insufferable pauses as we ruminate, test and argue over the safety of each tiny step, sometimes having to go backwards and find another path or add new paths that we thought would never be there. Slowly, ever so slowly and with infinite patience we gain altitude, only vaguely aware of the progress we have made. The really hard part is knowing when the mountain has been scaled. Too often it appears that the summit is ahead and we can relax, only to discover that the top is further ahead than it appears, and yet another push must be mustered. Of course the top really can NOT be seen and no one knows for certain, until it is over.

I do find though that there is a feeling I get that tells me the top is there in front of me (if only I could see it). It is really a feeling that we have run out of places to put our feet. No more tests left to ponder, no more problem reports to close, no more reviews to hold, only a far away machine waiting for Mars to arrive. I think we have nearly run out of places to put our feet. Could it be that we are there? Almost, I see a couple of more places to step. Next couple of week perhaps?

-Rob Manning
MSL Chief Engineer and faux climber

Opinions expressed are indeed those of the author and do not reflect the opinion of NASA/JPL/Caltech

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SFJCody
post Jul 17 2012, 07:48 AM
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QUOTE (MarsEngineer @ Jun 29 2012, 11:11 AM) *
You know I can't tell you how much fun it is to come by here (I wish I had more time!!!). I get a huge kick from the thoughtful discussions of risk, and the fun walks through memory lane (like the link that SFJCody left on Post#169 to a 1997 bulletin board about the weirdness of Pathfinder's landing system and even a discussion about my old web page on EDL I created back then - what a hoot!)


Awesome to know, thanks! I just recently noticed that someone has uploaded CNN's coverage of the Pathfinder landing to youtube.

http://www.youtube.com/watch?v=zUaalbRC7KA

http://www.youtube.com/watch?v=7Au-S-tjyiU



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MarsEngineer
post Jul 17 2012, 11:05 PM
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QUOTE (SFJCody @ Jul 17 2012, 12:48 AM) *
Awesome to know, thanks! I just recently noticed that someone has uploaded CNN's coverage of the Pathfinder landing to youtube.

http://www.youtube.com/watch?v=zUaalbRC7KA

http://www.youtube.com/watch?v=7Au-S-tjyiU


Thank you SFJCody! You made my day. I had never seen the CNN coverage of Pathfinder coverage - at least if I did, I do not recall seeing it. (Yikes! I sounded like a DJ! But I am relieved to see that I have not aged a day! Not). There were moments that I had long forgotten. Those were happy moments. With a little luck we will have another one of those highly addicting moments.


I just spent the bulk of the day discussing MSL contingency procedures we have been developing for what we would do if we lost the signal(s) during EDL and immediately thereafter (of course we are considering ODY's targeting situation that Pete talked about - but I am not concerned by it). We have generic contingencies for the rover, but we needed a special one for the EDL - Sol 0 day. There are a lot of nerve-wracking ways for the signals to cease flowing and yet still allow us to recover the rover later on. So spent half the day reviewing and refining the plan.

It is amazing how much time we spend on the "negative" (i.e. things that can go wrong). It can easily get us down, but we have to do this in order to find and "mitigate" all of the risks that we face. We do this so that we can get that rush when everything works right and pages of new science text books flow down to us. Years of work trying to find all of the ways it won't work only to have what works left over.

-Rob

Comments are those of the author and do not represent the views of NASA/JPL/Caltech.
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jmknapp
post Jul 17 2012, 11:55 PM
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QUOTE (MarsEngineer @ Jul 17 2012, 07:05 PM) *
There were moments that I had long forgotten. Those were happy moments.


I watched that too--it was hard to miss your smile after talking about all the pyrotechnics that went off on the 4th of July:



It was an amazing thing--if I recall correctly I was at someone's house for a party and the TV was on around midnight or the wee hours (ET), showing (practically) live pictures from Mars--mindblowing.



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Posts in this topic
- nprev   MSL Approach Phase   Jun 23 2012, 05:32 PM
- - Stu   Approach Phase. Blimey. Buckle up, people.   Jun 23 2012, 06:54 PM
- - imipak   ...and extinguish all cigarettes? Doesn't time...   Jun 23 2012, 10:23 PM
- - Oersted   Good write-up by elakdawalla here: http://www.plan...   Jun 25 2012, 12:54 PM
|- - mcaplinger   QUOTE (Oersted @ Jun 25 2012, 04:54 AM) J...   Jun 27 2012, 03:41 AM
- - Lightning   A third (and short) TCM occured yesterday. The spa...   Jun 27 2012, 09:06 AM
- - Oersted   Ok, I found the answer to which way the entry conf...   Jun 27 2012, 10:19 PM
- - brellis   A question I had for Emily's *very entertainin...   Jun 28 2012, 01:25 AM
- - PDP8E   I assume the cruise stages 'burn-up' (no h...   Jun 28 2012, 02:28 AM
- - djellison   I've had a look downrange for Opportunity in w...   Jun 28 2012, 05:21 AM
- - brellis   Thanks Doug. So, on flat terrain, MSL can handle a...   Jun 28 2012, 12:25 PM
- - djellison   And we have 30+ years of improvements in radar, IM...   Jun 28 2012, 02:11 PM
- - ElkGroveDan   I'd also wager that those are spec tolerances....   Jun 28 2012, 04:51 PM
- - MarsEngineer   Hi again, Doug is correct (he seems to have the k...   Jun 29 2012, 01:11 AM
|- - SFJCody   QUOTE (MarsEngineer @ Jun 29 2012, 11:11 ...   Jul 17 2012, 07:48 AM
|- - MarsEngineer   QUOTE (SFJCody @ Jul 17 2012, 12:48 AM) A...   Jul 17 2012, 11:05 PM
|- - jmknapp   QUOTE (MarsEngineer @ Jul 17 2012, 07:05 ...   Jul 17 2012, 11:55 PM
- - nprev   Rob, and we are absolutely delighted when you do h...   Jun 29 2012, 01:18 AM
- - Tesheiner   RE: MSL Approach Phase   Jun 29 2012, 06:43 AM
- - Pertinax   Hi Rob, Thank you for you post, particularly for ...   Jun 29 2012, 12:19 PM
- - Oersted   I wonder whether the planning and programming for ...   Jun 29 2012, 02:33 PM
|- - MarsEngineer   QUOTE (Oersted @ Jun 29 2012, 07:33 AM) I...   Jun 29 2012, 07:04 PM
|- - Oersted   QUOTE (MarsEngineer @ Jun 29 2012, 09:04 ...   Jun 30 2012, 01:21 AM
- - nprev   Rob, if you have the time & feel like it, I...   Jun 29 2012, 09:54 PM
- - DavidVicari   Rob, Thanks for the great replies!! You ...   Jun 30 2012, 01:48 AM
- - mchan   Another thanks to MarsEngineer. Your perspective ...   Jun 30 2012, 06:22 AM
- - Oersted   "JPLnews" Youtube channel: Martian Seri...   Jun 30 2012, 10:20 AM
- - claurel   I noticed that there's a relatively recent SPI...   Jul 2 2012, 12:36 AM
- - fredk   Sorry if this has been discussed, but I noticed Sc...   Jul 2 2012, 04:54 PM
- - elakdawalla   Scott insists that the rover is a "he" a...   Jul 2 2012, 05:08 PM
|- - ElkGroveDan   QUOTE (elakdawalla @ Jul 2 2012, 10:08 AM...   Jul 6 2012, 10:00 PM
- - stevesliva   ^ Curious George   Jul 2 2012, 05:21 PM
- - djellison   I call the testbed rover George - but I'm stil...   Jul 2 2012, 05:36 PM
- - RoverDriver   Since curiosity in italian is LA curiosita' (f...   Jul 2 2012, 05:55 PM
|- - climber   QUOTE (RoverDriver @ Jul 2 2012, 07:55 PM...   Jul 2 2012, 07:40 PM
|- - pospa   QUOTE (climber @ Jul 2 2012, 09:40 PM) Wo...   Jul 3 2012, 07:06 AM
|- - CryptoEngineer   QUOTE (pospa @ Jul 3 2012, 03:06 AM) As w...   Jul 6 2012, 04:50 AM
|- - SteveM   Since English has almost no gendered nouns and Cur...   Jul 6 2012, 05:06 PM
- - brellis   The third chapter of Emily's excellent series ...   Jul 7 2012, 12:01 AM
|- - Tom Tamlyn   QUOTE (brellis @ Jul 6 2012, 07:01 PM) I...   Jul 21 2012, 02:08 AM
|- - RoverDriver   QUOTE (Tom Tamlyn @ Jul 20 2012, 07:08 PM...   Jul 21 2012, 02:22 AM
|- - Tom Tamlyn   QUOTE (RoverDriver @ Jul 20 2012, 10:22 P...   Jul 21 2012, 06:17 AM
- - Oersted   Just the suspension inherent in the rocker-bogie w...   Jul 8 2012, 05:14 AM
- - RoverDriver   Yep, the suspension system is released with spring...   Jul 8 2012, 05:25 AM
- - brellis   Reading this article about MSL and "fresh cra...   Jul 8 2012, 08:47 PM
|- - djellison   QUOTE (brellis @ Jul 8 2012, 01:47 PM) I ...   Jul 9 2012, 03:27 PM
- - nprev   I think that the overriding concern is still resid...   Jul 8 2012, 09:13 PM
|- - RoverDriver   I haven't heard anything about observing the d...   Jul 8 2012, 10:26 PM
||- - centsworth_II   There was a reason to examine MER's heat shiel...   Jul 9 2012, 06:56 AM
|- - charborob   QUOTE (nprev @ Jul 8 2012, 04:13 PM) The ...   Jul 9 2012, 01:38 AM
- - Explorer1   Spirit's trenches were that deep at least. Spe...   Jul 9 2012, 06:21 AM
- - Phil Stooke   And we'll see it with HiRISE. Points on a map...   Jul 9 2012, 03:37 PM
- - djellison   HiRISE will have... Rover Crashed Descent Stage B...   Jul 9 2012, 04:20 PM
|- - Oersted   QUOTE (djellison @ Jul 9 2012, 06:20 PM) ...   Jul 9 2012, 08:03 PM
- - B Bernatchez   I wonder if the first two ballast masses wouldn...   Jul 9 2012, 05:05 PM
- - climber   Would be fun to look for the ballast. Total weight...   Jul 9 2012, 07:38 PM
- - Explorer1   That's welcome news; no need for a heavy shove...   Jul 9 2012, 08:54 PM
|- - walfy   There was some discussion a week or two ago about ...   Jul 10 2012, 03:29 AM
- - djellison   Remember - the descent stage doesn't land with...   Jul 10 2012, 06:06 AM
|- - Paolo   QUOTE (djellison @ Jul 10 2012, 08:06 AM)...   Jul 10 2012, 07:54 AM
|- - pospa   QUOTE (djellison @ Jul 10 2012, 08:06 AM)...   Jul 10 2012, 03:45 PM
- - djellison   As I said - the mast would still be stowed, thus C...   Jul 10 2012, 03:59 PM
|- - walfy   QUOTE (djellison @ Jul 10 2012, 07:59 AM)...   Jul 11 2012, 04:29 AM
- - nprev   Noticed this article on the New York Times today r...   Jul 11 2012, 05:32 AM
- - djellison   About a year ago, a bunch of us were swapping you-...   Jul 11 2012, 05:49 AM
- - climber   Mars is now visible from Curiosity as a 3'arc ...   Jul 11 2012, 05:53 AM
- - Oersted   Odyssey in safe mode again, acc. to Paolo (JPL rov...   Jul 12 2012, 01:36 PM
- - climber   Pre_landing telecon tonight at 10AM Pacific: http:...   Jul 16 2012, 05:18 AM
|- - jmknapp   QUOTE (climber @ Jul 16 2012, 01:18 AM) P...   Jul 16 2012, 02:05 PM
|- - ElkGroveDan   QUOTE (climber @ Jul 15 2012, 10:18 PM) P...   Jul 16 2012, 03:11 PM
- - akuo   Missed the press conf live, but its already visibl...   Jul 16 2012, 07:32 PM
|- - jmknapp   QUOTE (akuo @ Jul 16 2012, 03:32 PM) Miss...   Jul 16 2012, 08:15 PM
- - RoverDriver   20x25 Km is the nominal size for the ellipse. I d...   Jul 16 2012, 07:40 PM
- - Phil Stooke   The ellipse was reduced in size a few weeks ago: ...   Jul 16 2012, 07:42 PM
- - akuo   Ok, I haven't followed the official MSL site k...   Jul 16 2012, 07:51 PM
- - djellison   21 x 7km is the size I used for the artwork   Jul 16 2012, 10:23 PM
- - jmknapp   An important item from the press conference was th...   Jul 17 2012, 12:40 AM
|- - stewjack   QUOTE (jmknapp @ Jul 16 2012, 07:40 PM) O...   Jul 17 2012, 01:42 AM
- - brellis   Dang it, I'm already half way through the firs...   Jul 17 2012, 03:11 AM
- - nprev   Just for clarity's sake, we're talking abo...   Jul 17 2012, 03:17 AM
|- - Syrinx   QUOTE (nprev @ Jul 16 2012, 07:17 PM) we...   Jul 17 2012, 03:42 AM
|- - atomoid   QUOTE (nprev @ Jul 16 2012, 08:17 PM) Jus...   Jul 18 2012, 02:00 AM
- - djellison   The baseline plan was... X-Band DTE Tones up unti...   Jul 17 2012, 03:38 AM
- - djellison   Oh - the MARDI dataset is 1600 x 1200 x approx 500...   Jul 17 2012, 03:49 AM
- - Lightning   This means in case ODY can not be present at the r...   Jul 17 2012, 06:14 AM
- - djellison   There would be DTE tones until the Earth sets ( af...   Jul 17 2012, 07:42 AM
- - brellis   Wouldn't some limited direct transmit get reco...   Jul 18 2012, 05:25 AM
- - djellison   QUOTE (atomoid @ Jul 17 2012, 06:00 PM) ....   Jul 18 2012, 05:37 AM
|- - malgar   QUOTE (djellison @ Jul 18 2012, 07:37 AM)...   Jul 18 2012, 06:42 AM
- - Astro0   There are tones from Cruise stage sep all the way ...   Jul 18 2012, 06:59 AM
- - climber   As I red somewhere, if ODY isn't in the right ...   Jul 19 2012, 01:24 PM
|- - MahFL   There seems to be a glaring error in the press kit...   Jul 19 2012, 01:38 PM
- - Explorer1   Well, technically it is 'post-launch', rig...   Jul 19 2012, 04:04 PM
- - SpaceListener   I would like to know what are the X-Band tones and...   Jul 19 2012, 11:06 PM
|- - SteveM   QUOTE (SpaceListener @ Jul 19 2012, 06:06...   Jul 19 2012, 11:36 PM
|- - djellison   QUOTE (SpaceListener @ Jul 19 2012, 04:06...   Jul 21 2012, 06:44 AM
- - djellison   I've not seen one publicly available.   Jul 19 2012, 11:42 PM
- - RoverDriver   The first pdf file I see by searching "descan...   Jul 20 2012, 01:26 AM
- - Astro0   Thanks Paolo. This is an excellent 5.46mb pdf docu...   Jul 20 2012, 06:36 AM
- - climber   As we'll loose direct contact during parachutt...   Jul 23 2012, 08:04 AM
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