MSL Video Options

[remcook]

Wow, it's getting really close now. Fingers crossed multiple times!

[eoincampbell]

Mr Manning stopping by, how awesome is that! All the very best for the mission. MSL is lucky to have such EDL legends in attendance...

[MarsEngineer]

Ditto Rob, in the thanks-for-dropping-by parade.

On the subject of the heat-shield recon, has there been any kind of paper, journal interview, or other public summary of what was learned? Even in a very general sense? Or is that data all still proprietary?

Hi ElkGroveDan,

Not proprietary, just slow to come out (paper writing is becoming a more of a hobby these days - not enough hours in the day). There were at least two papers published. The summary paper was finally published at the 42nd AIAA Thermophysics Conference last June. In summary we concluded that the char depth of the heat shield material matched our predictions (yea!). We also learned that a piece of a mylar blanket that skirted the heat shield became a "flap" that induced some minor but very noticeable wiggles of the entry vehicle (capsule) during Opportunity's entry just before parachute deployment. The blanket was supposed to fully melt away during entry but we found that part of it did not (it was on Mars still attached to the crumpled heat shield). Its position and size matched our entry dynamic simulations for a flapping flap. Needless to say MSL does not have a blanket covering its heat shield (neither did Phoenix).

back to work ...

-Rob

[elakdawalla]

That one took a little more detective work than usual to locate. The citation: "Mars Exploration Rover Heatshield Observation Campaign," by C. Szalai; B. Thoma; W. J. Lee; J. Maki; W. Wilcoxson; E. Venkatapathy; T. White. There's no abstract online but there is an 11-page Powerpoint presentation (PDF, 4 MB). I was able to look at the first couple pages of the PDF but the download appears to be hanging for me.

[ugordan]

I was able to look at the first couple pages of the PDF but the download appears to be hanging for me.

Happens often to me in Firefox. I find it's safer/quicker to download the thing properly and open it afterward than let the PDF plugin handle preload.

[Paolo]

the download appears to be hanging for me.

had the same problem under firefox. it downloaded nicely using wget

[eoincampbell]

From the animation so full of detail, could someone explain the propellant tank discoloration patterns on the descent stage ?
Some great close-ups of descent stage included here.

[djellison]

That's just a thin foam jacket around the tanks - wrapped in kapton tape. Before launch, they also got silver MLI blankets as well.

Good photo in a more finished config - here - http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA15020

[pospa]

In this traditional pre-landing video Seven Minutes of Terror they mention 76 pyrotechnic devices that must work just perfect during EDL to have succesfull landing.
Does anybody know if some of them are in pair = main + backup pyro, or every single of them serves for specific task?

Or the best would be some list of all 76 pcs with description of dedicated function, something like:
1 - 3 : cruise stage separation
4 - 5 : balance mass ejecting (2 x 75 kg)
6 - 11 : balance mass ejecting (6 x 25 kg)
12 : parachute jettisoning
13 - 18 : heat shield separation
...
...

[MarsEngineer]

Yes, 76 is about right. And yes, each is for a separate "task" (some, like the 9 pyro separation nuts around the perimeter of the heat shield that hold it in place share duties but all have to fire to release the heatshield). Nearly all 76 of these must work (there is some redundancy in the thermal batteries, but that is about it). Another handful are fired after landing in the first hour to release the equipment needed for the surface mission (high gain antenna, arm, mast, etc) for a total of about 81.

Compare with MER. MER fired 37 pyros during EDL (through touchdown and rolling to a stop in the airbags). Another 18 pyro devices were needed to get the rover upright and into a configuration with the lander petals and solar arrays open and another 9 in the days afterward for the equipment needed for the surface mission (rover stand up, high gain antenna, arm, mast, etc) for a total of 64. So MSL has about 26% more than MER in total.

Like on MER, all of these pyro device have redundant electrical initiators (mostly NASA Standard Initiators or NSI's) so if we failed to get enough current into one, the redundant circuits will do the trick.

There are a lot of other pyros you do not list, like the in-space freon vent, the filling of the propulsion lines, cable cutters (electrical), rover wheel releases etc.

I find it best not to think about it too much any more. (Because folks have - day and night for a long time now.)

We have successfully tested every one of these device (designs) many times and over the years we have developed a lot of confidence in them.

-Rob Manning

[nprev]

Thanks very much, Rob; always a pleasure to hear the definitive scoop from a pro!

[MarsEngineer]

My pleasure as well, nprev. It is good to see you still at it. I wish I had more time to visit more often.

For you and the gang: you might be wondering what we are up to. As seems typical of this time before landing (yeah, I should post this in the "Approach" thread), we spend 90% of our time on those 500,000 lines of code. Not that it is buggy, but we want to make sure that it works under a wide range of potential (low probability) "off nominal" (our popular euphemism for bad or unexpected) situations. So we spend a lot of time injecting these bad things into the testbed and looking to ensure that the software muscles through it. It seems to be doing well for the vast majority of the things we through at it. I am talking about both the EDL version of software (R9) and the version we will boot into in the first week after landing (R10).

It is definitely a case of fine tuning. The hard part is that we could keep doing this until the cows come home (or landing is over). We have done the same for all our Mars missions.


-Rob

[pospa]

Yes, 76 is about right. And yes, each is for a separate "task" ... Like on MER, all of these pyro device have redundant electrical initiators (mostly NASA Standard Initiators or NSI's) so if we failed to get enough current into one, the redundant circuits will do the trick.

Thank you very much, MarsEngineer; I'm very pleased to get reply directly from you
You confirmed my assumption about redundant initiators (no backup pyros). Now I can finally convince some of doubters within our "cosmo gang" in CZ.
Thanks a lot !

Also thanks for the latest team activity update.
Yours faithfully pospa

[Guest_Oersted_*]

...the version we will boot into in the first week after landing (R10).

As for code sent to Mars, is any being uploaded to MRO/HiRise for MSL's EDL? None of us will forget the great job by you and others to capture the iconic Phoenix over Heimdall image. Are we again perhaps fortunate with the conjunction of spacecraft trajectories this time around? I won't even begin to ask about the backdrop... ;-)

Good vibes and peanut-chomping from Europe,

Oersted

[djellison]

HiRISE will be trying again to get MSL during EDL. As with PHX - it will require good planning..AND good fortune to actually get it.