Author Topic: LIVE: MSL Curiosity Rover ENTRY, DESCENT, LANDING - Aug 5-6, 2012  (Read 275444 times)

Offline robertross

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Also, I've moved on from JPL to another company, and when I left my understanding was the the first images *uplinked* would be with the covers open, and the images with the covers closed would be taken but uplinked later, much like the MARDI images.

I guess with the communications window from Odyssey being so tight, they decided to bin down and grab the images with closed covers right away, because the opening sequence might not have completed before the end of the comm window...  So I had no idea my hardware was going to be so famous.  They even made that cool press-release quality animation for the final pre-landing press conference yesterday.

You now have a great moment to carry with you, congrats.

Thanks for the earlier details on the covers. I always like seeing perfectly good hardware put to use, even years later

Offline Garrett

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I was the cognizant engineer on these now-world-famous dust covers, I guess I can stop lurking and talk about them a little bit.

Thanks very much for taking the time to give us that detailed and authoritative account. Much appreciated...

Noel

+1

Great to have an inside engineering story like that.
- "Nothing shocks me. I'm a scientist." - Indiana Jones

Offline Pheogh

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If the hydrazine was going to be a possible issue why didn't they just pre-command the descent stage to expend all prop and crash ballistically?
That appears to be essentially what they did, and there would still be residual hydrazine in the wreckage.

Not to beat a dead horse here but I am not so sure. The data in hand suggest they had nearly 120kg of Hydrazine remaining nearly 1/4 of margin from the total. That seems like it would provide an awful lot of deltaV especially with out roughly 1 ton rover attached?

The purpose of my inquiry is that a question was asked how far afield the descent stage might have landed and with the extra hydrazine on board is there a contamination issue.

If it did deplete the prop and then crash both of these concerns would be essentially moot but I didn't here Miguel dispel it that in any way. What I heard was that we just tried to get is as far away as possible 100m or so.

In short if anyone has confirmation that the descent stage was commanded to fly until prop depletion I would love to know that. I am with the reporter that asked the original question; seems to me that leaking hydrazine would present a significant concern to the science?

Offline marsman2020

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marsman2020, thanks for that great explanation about the covers. Answers my question about why some dust managed to sneak past the covers anyway.

Do you (by any chance) know how well-protected the scientific cameras are?

The cameras on the Remote Sensing Mast (4x engineering NavCams, MastCams, and ChemCam are protected by features in the interface between the stowed RSM and the rover top deck.  The Mars Hand Lens Imager on the turret has its own dust cover with a motor that can open and close it throughout the mission, so it is protected as well.

The main challenge with the HazCams is that they are right at the lower outer edged of the rover chassis, directly in the path of any reflected flow and its associated excavated material from the landing engines during touchdown.  The 4 front cameras are in two interleaved pairs (ABAB) at the center of the front panel of the chassis; the rears are 1 pair on each side of the RTG (AA  ||| BB).  From the pictures it looks like the front covers got hit pretty good with the caked on material, and the rears received a good dusting.

The NavCams can stand in for the HazCams during autonomous navigation if needed, but because they are a different focal length and multiple pictures have to be taken and processed it slows down driving to the point where with NavCams alone, the minimum mission success criteria wouldn't be met.  Also the front HazCams are used to image the workspace of the robotic arm/turret for the operation of the sampling system.  All that payed into the decision to protect the HazCams as best we could.  (I didn't actually make that decision, I just made it happen.)

When the RSM deploys it will take a panorama "self portrait" of the rover and we will have a better idea of what the dust situation is.

Online DaveS

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If the hydrazine was going to be a possible issue why didn't they just pre-command the descent stage to expend all prop and crash ballistically?
That appears to be essentially what they did, and there would still be residual hydrazine in the wreckage.

Not to beat a dead horse here but I am not so sure. The data in hand suggest they had nearly 120kg of Hydrazine remaining nearly 1/4 of margin from the total. That seems like it would provide an awful lot of deltaV especially with out roughly 1 ton rover attached?

The purpose of my inquiry is that a question was asked how far afield the descent stage might have landed and with the extra hydrazine on board is there a contamination issue.

If it did deplete the prop and then crash both of these concerns would be essentially moot but I didn't here Miguel dispel it that in any way. What I heard was that we just tried to get is as far away as possible 100m or so.

In short if anyone has confirmation that the descent stage was commanded to fly until prop depletion I would love to know that. I am with the reporter that asked the original question; seems to me that leaking hydrazine would present a significant concern to the science?
The descent stage did not burn until depletion. It just throttled up the four canted thrusters to 100% for 6 seconds, then sent due north and then cut-off the thrusters and then flew on a ballistic trajectory and impacted the surface.
"For Sardines, space is no problem!"
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Offline rdale

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The data in hand suggest they had nearly 120kg of Hydrazine remaining

140kg per presser.

Quote
The purpose of my inquiry is that a question was asked how far afield the descent stage might have landed

They don't know, HiRISE might answer in the next two weeks.

Quote
with the extra hydrazine on board is there a contamination issue.

Issue is probably a strong word.

Quote
seems to me that leaking hydrazine would present a significant concern to the science?

"Significant" is probably too strong of a word. But regardless, that is why they sent it north where they aren't going.

Offline Lars_J

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marsman2020, Thanks for all the background info! :)

Your work (& that of everyone else involved with MSL) is very much appreciated. This is going to be a fun mission to follow.

Offline Pheogh

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The data in hand suggest they had nearly 120kg of Hydrazine remaining

140kg per presser.

Quote
The purpose of my inquiry is that a question was asked how far afield the descent stage might have landed

They don't know, HiRISE might answer in the next two weeks.

Quote
with the extra hydrazine on board is there a contamination issue.

Issue is probably a strong word.

Quote
seems to me that leaking hydrazine would present a significant concern to the science?

"Significant" is probably too strong of a word. But regardless, that is why they sent it north where they aren't going.

Thanks guys. Will be nice to see where it landed once HiRISE gets a chance.

Offline marsman2020

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Even just having the covers there and making them clear so we could assess what hit them gives useful information for future rovers.  It was still an open question among some members of the MSL team if they were really "needed" or not.  Even after I built the hardware and tested it many times with an EM HazCam, there was some consternation about putting a pyro so close to the cameras.  This is a good example of high quality systems engineering - taking the lessons learned from another mission (Phoenix) and applying them into MSL within months, even though it caused a lot of heartburn and added cost - because it was the right thing to do to ensure the success of the mission.

Oh, I forgot to add - in the pictures with the covers closed, there are pan head bolts with washers under them that hold the clear Lexan in place with "just enough" force that it can still slide with respect to the aluminum cover structure during thermal expansion/contraction.  One of those is a small Belleville disc spring....that I bought from McMaster-Carr.  It was one of their items that has a materials/lot certification to the relevant AMS spec included, and we did additional materials and force:deflection testing on samples of the lot so my materials engineer would let me fly it.  Since we had those testing facilities in-house, it was less costly and faster to qualify an the off the shelf part (for a low-risk application) vs having a custom run of parts made. 
« Last Edit: 08/06/2012 06:38 pm by marsman2020 »

Offline Star One

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Marsman2020 thanks for all your really interesting information on this.

Offline Jim

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If the hydrazine was going to be a possible issue why didn't they just pre-command the descent stage to expend all prop and crash ballistically?

They wanted to do a known maneuver and not worry about dispersion.

Offline Pheogh

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If the hydrazine was going to be a possible issue why didn't they just pre-command the descent stage to expend all prop and crash ballistically?

They wanted to do a known maneuver and not worry about dispersion.

Understood but in this case wouldn't it be safe to assume that a longer burn or maximum burn would have only moved that dispersion farther afield? I can't imagine a scenario where it burns so long and so squirrel-ly that it actually returns "closer" to the landing site?

Offline marsman2020

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I recall hearing at one point that the descent stage has a very limited computer capability, so the sequence that it could run after the bridal separation had to be deliberately simple.

The design on MSL was to use the rover computer for everything....  So a more complex sequence for a burn to depletion might not have been an option.

Offline John44

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Mars Science Laboratory/Curiosity Rover Post-Landing News Briefing - Landing Recap and Sol 1 Outlook
http://www.space-multimedia.nl.eu.org/index.php?option=com_content&view=article&id=7763
« Last Edit: 08/06/2012 07:03 pm by John44 »

Offline ugordan

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A few new images have been downlinked, in full resolution this time. Mount Sharp in view!
« Last Edit: 08/06/2012 07:38 pm by Chris Bergin »

Offline marsman2020

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Front HazCam cover deployed!

Look at those nice clean cameras!

Offline Pheogh

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A few new images have been downlinked, in full resolution this time. Mount Sharp in view!

WOW!! look at those mounds over to the left of image!!!

Offline iamlucky13

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Quote
with the extra hydrazine on board is there a contamination issue.

Issue is probably a strong word.

Quote
seems to me that leaking hydrazine would present a significant concern to the science?

"Significant" is probably too strong of a word. But regardless, that is why they sent it north where they aren't going.

Call it a "concern." It's still a legitimate reason to avoid the descent stage. I haven't heard if they might look for the backshell, heat shield, or cruise balance weights. They also can "scuff" the soil with the wheels to get shallow trenches to examine.

The criteria here is basically better safe than sorry. SAM contains several very sensitive instruments...far more so than anything on the MER's. The value of that sensitivity is compromised if you detect something that just as easily could be from the descent stage as from Mars itself.

Then what was the purpose of that video?

He was joking. We'll see it in a few days. It provides local context of the landscape around the lander. This will help the science team plan the initial drives based on what appears interesting or challenging in higher resolution than what can be seen from orbital images. More info here from the company that built the camera:

http://www.msss.com/science/msl-mardi-science-objectives.php

Offline ugordan

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I think this downlink means there's a good chance we got some of the MARDI thumbnails down as well. Too bad we have to wait for the press conference a 4 PM Pacific to see them.

Offline Pheogh

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With this front hazcam I would think we could pinpoint pretty well where we are?

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