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MSL - landing day, Got any plans?
MahFL
post May 2 2012, 08:58 PM
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I took the Monday off so I can stop up very late, until we get the pictures back from post landing.
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Astro0
post May 2 2012, 10:31 PM
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I've got the best gig of all!
It's going to be the afternoon of Monday August 6 here and landing is set for 3:18 SCT and 3:32 ERT.

I'll be hosting an event at Canberra DSN with a few hundred people watching events on NASA TV and looking out the window at the antennas providing the communication link to MSL/MRO/ODY smile.gif

Any locals interested in coming along are welcome. wink.gif
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Astro0
post May 3 2012, 05:21 AM
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This is a real treat from Matt Heverly, Mobility Systems Engineer for the Mars Science Laboratory rover.
He tweeted this very cool image...

Attached Image


A great shot from the JPL Mars Yard and something I hope we see a lot more of when Curiosity arrives at Gale Crater smile.gif
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stevesliva
post May 3 2012, 05:42 AM
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Might be unnerving if we saw bootprints.
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djellison
post May 3 2012, 05:51 AM
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Note how soft the edge of the shadows are... a symptom of being closer to the sun, thus it's angular size being much larger.
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JohnVV
post May 3 2012, 06:03 AM
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---edit---
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jamescanvin
post May 3 2012, 07:22 AM
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QUOTE (JohnVV @ May 3 2012, 07:03 AM) *
and our much thicker atmosphere


No, the softness of the shadow edge is purely due to geometry; the angular size of the sun and the distance of the shadow from the object.

As MSL is so much bigger than MER this image is on a different scale to what we are used to, so that will also contribute to the odd look of the shadows.


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djellison
post May 3 2012, 07:26 AM
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QUOTE (JohnVV @ May 2 2012, 11:03 PM) *
and our much thicker atmosphere
the air will play a much bigger role


As James points out - the softness is down to geometry alone.

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brellis
post May 3 2012, 11:14 PM
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I remain - uh, Curious - about the factor of atmosphere in calculating the trajectory of the landing of MSL. When was the likely atmospheric effect established, and from what data? Because, parachute? On Mars?? Just ask weathermen on earth, that atmosphere can change a lot!
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Drkskywxlt
post May 3 2012, 11:35 PM
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QUOTE (brellis @ May 3 2012, 06:14 PM) *
I remain - uh, Curious - about the factor of atmosphere in calculating the trajectory of the landing of MSL. When was the likely atmospheric effect established, and from what data? Because, parachute? On Mars?? Just ask weathermen on earth, that atmosphere can change a lot!


MSL will actively control its descent, watch the EDL video on Youtube to see that. That's what allows it to have such a small landing ellipse relative to past missions. But, there still is atmospheric data that is incorporated into the plan. That data comes primarily from general circulation modeling, augmented with mesoscale modeling. These models have been "tuned" based on available atmospheric data (e.g., Viking landers, TES, MCS, etc...). The models provide a range of expected density, pressure and wind profiles during descent and that constrains the engineering problem. The atmospheric density on Mars is far more variable than on Earth, but it is of course much much less in absolute terms.
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MahFL
post May 4 2012, 12:38 PM
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I was under the impression the only actively guided part was the initial ballistic entry using the Nitrogen jets on the back shell. After that it's not guided, as one of the team said later they hope to add more active guidance and keep shrinking the landing circle to 7 km or so on future missions. The initial guidance though of course helps make the landing circle a bit smaller this time.






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Drkskywxlt
post May 4 2012, 03:02 PM
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QUOTE (MahFL @ May 4 2012, 08:38 AM) *
I was under the impression the only actively guided part was the initial ballistic entry using the Nitrogen jets on the back shell. After that it's not guided, as one of the team said later they hope to add more active guidance and keep shrinking the landing circle to 7 km or so on future missions. The initial guidance though of course helps make the landing circle a bit smaller this time.


Yeah, that's what I was referring to.
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djellison
post May 4 2012, 04:26 PM
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QUOTE (MahFL @ May 4 2012, 05:38 AM) *
I was under the impression the only actively guided part was the initial ballistic entry using the Nitrogen jets on the back shell.


Here's the best single document describing EDL
http://trs-new.jpl.nasa.gov/dspace/handle/2014/41629

Best section is this

QUOTE
The MSL entry guidance algorithm is divided into four phases. Entry interface marks the start of guided entry:
guidance is initialized in the pre-bank phase and the controller commands bank attitude hold until the sensed acceleration exceeds 0.5 Earth gs.
Once the sensed acceleration exceeds the specified trigger limit, the range control phase begins. During the range control phase, the bank angle is commanded to minimize predicted downrange error at parachute deployment.
Throughout this phase, cross-range error is maintained with a manageable deadband limit by executing bank reversals as necessary.
Peak heating and peak deceleration occur during this guidance phase.
Once the navigated relative velocity drops below about 900 m/s, guidance transitions to a heading alignment phase to minimize residual cross-range error before parachute deployment.
Just prior to parachute deployment, the vehicle angle of attack is adjusted to 0 by ejecting balance masses while the azimuth is aligned for better radar performance later during parachute descent. Parachute deployment is triggered at a navigated velocity of over 450 m/s.


A small point - it's not nitrogen - it's hydrazine thrusters. Infact the 8 thrusters on the back of the backshell to control attitude / roll during guided entry are the same model of thruster used in clusters for Phoenix terminal descent ( Aerojet MR-107U )

This document is more specifically about the guided entry phase - including some nice charts of sim-runs
http://www.planetaryprobe.eu/IPPW7/proceed...ssion5/p453.pdf
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cbcnasa
post May 4 2012, 06:09 PM
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QUOTE (elakdawalla @ May 1 2012, 11:30 PM) *
The Society will be having a Planetfest in Pasadena, for those of you eager to celebrate (or mourn) with 2000 other rabid fans. There is discussion of trying to create satellite Planetfests; I'm not sure how likely that is to come to pass. I am 95% certain that our event will be webcast. How much value will be added to NASA TV I'm not sure (since we will be relying on NASA TV for the feed from mission control), but our event will be webcast.

As for me, I plan to be jumping up and down at JPL.


A Planetfest on the east coast sounds like a good idea any talk with locations for it?
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elakdawalla
post May 5 2012, 12:05 AM
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I am doing my level best to remain entirely ignorant of Planetfest planning, so that I can avoid any responsibility for it! So if the amount of information on our website doesn't satisfy you (it shouldn't, it's pretty thin right now) then send email to tps@planetary.org with your questions. The more you hassle them about certain things now, the more likely those things are to come to pass smile.gif


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