IPB

Welcome Guest ( Log In | Register )

10 Pages V  « < 7 8 9 10 >  
Reply to this topicStart new topic
MSL Video
remcook
post Nov 23 2011, 03:17 PM
Post #121


Rover Driver
****

Group: Members
Posts: 1001
Joined: 4-March 04
Member No.: 47



Wow, it's getting really close now. Fingers crossed multiple times!
Go to the top of the page
 
+Quote Post
eoincampbell
post Nov 23 2011, 05:13 PM
Post #122


Member
***

Group: Members
Posts: 384
Joined: 28-August 07
From: San Francisco
Member No.: 3511



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...


--------------------
'She drove until the wheels fell off...'
Go to the top of the page
 
+Quote Post
MarsEngineer
post Nov 23 2011, 05:43 PM
Post #123


Junior Member
**

Group: Members
Posts: 89
Joined: 25-January 06
Member No.: 661



QUOTE (ElkGroveDan @ Nov 22 2011, 11:14 PM) *
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 ... wheel.gif

-Rob
Go to the top of the page
 
+Quote Post
elakdawalla
post Nov 23 2011, 06:24 PM
Post #124


Bloggette par Excellence
****

Group: Admin
Posts: 4415
Joined: 4-August 05
From: Pasadena, CA, USA, Earth
Member No.: 454



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.


--------------------
My blog - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
Go to the top of the page
 
+Quote Post
ugordan
post Nov 23 2011, 06:55 PM
Post #125


Senior Member
****

Group: Members
Posts: 3562
Joined: 1-October 05
From: Croatia
Member No.: 523



QUOTE (elakdawalla @ Nov 23 2011, 07:24 PM) *
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.


--------------------
Go to the top of the page
 
+Quote Post
Paolo
post Nov 23 2011, 06:58 PM
Post #126


Senior Member
****

Group: Members
Posts: 1339
Joined: 3-August 06
From: 43 35' 53" N 1 26' 35" E
Member No.: 1004



QUOTE (elakdawalla @ Nov 23 2011, 07:24 PM) *
the download appears to be hanging for me.


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


--------------------
I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.

James Van Allen
Go to the top of the page
 
+Quote Post
eoincampbell
post Jun 23 2012, 04:35 PM
Post #127


Member
***

Group: Members
Posts: 384
Joined: 28-August 07
From: San Francisco
Member No.: 3511



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.


--------------------
'She drove until the wheels fell off...'
Go to the top of the page
 
+Quote Post
djellison
post Jun 24 2012, 12:41 AM
Post #128


Administrator
****

Group: Chairman
Posts: 13744
Joined: 8-February 04
Member No.: 1



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
Go to the top of the page
 
+Quote Post
pospa
post Jun 24 2012, 07:56 PM
Post #129


Member
***

Group: Members
Posts: 144
Joined: 4-May 11
From: Pardubice, CZ
Member No.: 5979



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
...
...
Go to the top of the page
 
+Quote Post
MarsEngineer
post Jun 25 2012, 12:44 AM
Post #130


Junior Member
**

Group: Members
Posts: 89
Joined: 25-January 06
Member No.: 661



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. blink.gif (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
Go to the top of the page
 
+Quote Post
nprev
post Jun 25 2012, 03:00 AM
Post #131


Senior Member
****

Group: Moderator
Posts: 7002
Joined: 8-December 05
From: Los Angeles
Member No.: 602



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


--------------------
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.
Go to the top of the page
 
+Quote Post
MarsEngineer
post Jun 25 2012, 03:50 AM
Post #132


Junior Member
**

Group: Members
Posts: 89
Joined: 25-January 06
Member No.: 661



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
Go to the top of the page
 
+Quote Post
pospa
post Jun 25 2012, 06:43 AM
Post #133


Member
***

Group: Members
Posts: 144
Joined: 4-May 11
From: Pardubice, CZ
Member No.: 5979



QUOTE (MarsEngineer @ Jun 25 2012, 02:44 AM) *
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 rolleyes.gif
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
Go to the top of the page
 
+Quote Post
Guest_Oersted_*
post Jun 25 2012, 01:07 PM
Post #134





Guests






QUOTE (MarsEngineer @ Jun 25 2012, 05:50 AM) *
...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
Go to the top of the page
 
+Quote Post
djellison
post Jun 25 2012, 01:23 PM
Post #135


Administrator
****

Group: Chairman
Posts: 13744
Joined: 8-February 04
Member No.: 1



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.

Go to the top of the page
 
+Quote Post

10 Pages V  « < 7 8 9 10 >
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 2nd September 2014 - 06:56 PM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.