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Mro On Approach, TCM-3 not required
jmknapp
post Feb 16 2006, 03:35 PM
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I made an animation of the approach through the first orbit:

MRO approach movie (5.7MB MPG file)

It's from the point of view of a (fictitious) nadir-pointing camera with the same FOV (1.14 degrees) as HiRISE.


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djellison
post Feb 16 2006, 03:46 PM
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Given the addition of some post-moi-pre-aerobraking imaging, at what appears to be between about 0000 and 0600 on the 15th of March - any idea on a nadir target for that sort of time?

Doug
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jmknapp
post Feb 16 2006, 05:00 PM
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QUOTE (djellison @ Feb 16 2006, 10:46 AM) *
Given the addition of some post-moi-pre-aerobraking imaging, at what appears to be between about 0000 and 0600 on the 15th of March - any idea on a nadir target for that sort of time?

Doug


Looks like it's the north polar ice cap. Here's the view midway in that interval (+ marks the nadir point):



Note that the FOV above is 5 degrees. CTX has an FOV 0f 6 degrees; HiRISE 1.14 degrees.


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Guest_Sunspot_*
post Feb 16 2006, 05:15 PM
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I kept reading that they wouldn't be doing any imaging until after aerobraking was complete.. this is good news.
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mcaplinger
post Feb 16 2006, 05:34 PM
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QUOTE (jmknapp @ Feb 16 2006, 09:00 AM) *
Looks like it's the north polar ice cap. Here's the view midway in that interval (+ marks the nadir point):


Try looking (hint, hint) closer to 6:00 UTC.


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jmknapp
post Feb 16 2006, 06:03 PM
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QUOTE (mcaplinger @ Feb 16 2006, 12:34 PM) *
Try looking (hint, hint) closer to 6:00 UTC.


Hmmm... here is the view at 0600:



Wondering what you are hinting at--perhaps this is targeted after one of the proposed Phoenix landing sites? The subpoint above is 75N 141W.


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helvick
post Feb 16 2006, 06:30 PM
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QUOTE (jmknapp @ Feb 16 2006, 06:03 PM) *
Wondering what you are hinting at--perhaps this is targeted after one of the proposed Phoenix landing sites? The subpoint above is 75N 141W.

Possibly - I had a placeholder for Phoenix @ 70N 120W but I'm not sure where I got that from. I didn't think the precise landing site had been chosen yet though.
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Phil Stooke
post Feb 16 2006, 06:49 PM
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It wouldn't be targeted, just whatever they are seeing as they pass by.

Phil


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babakm
post Feb 16 2006, 07:05 PM
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Some imaging of Phoenix candidate site D is on the MSSS site (roughly 71N 115-120W). The closest image I could find to 75N 141W is this one, but your nadir looks like it's ~180 degrees away from the projection here. Different coord systems?
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RNeuhaus
post Feb 16 2006, 07:10 PM
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Below is the Sout Pole Cap that looks different than the Nort Pole Cap. The MRO will orbit around poles?



A much better resolution and visibilty is below:


This is the south polar cap of Mars as it appeared to the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) on April 17, 2000. In winter and early spring, this entire scene would be covered by frost. In summer, the cap shrinks to its minimum size, as shown here. Even though it is summer, observations made by the Viking orbiters in the 1970s showed that the south polar cap remains cold enough that the polar frost (seen here as white) consists of carbon dioxide. Carbon dioxide freezes at temperatures around -125 C (-193 F). Mid-summer afternoon sunlight illuminates this scene from the upper left from about 11.2 above the horizon. Soon the cap will experience sunsets; by June 2000, this pole will be in autumn, and the area covered by frost will begin to grow. Winter will return to the south polar region in December 2000. The polar cap from left to right is about 420 km (260 mi) across

Rodolfo
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brianc
post Feb 16 2006, 08:00 PM
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A nice article about the MRO HIRISE camera system here

http://www.phim.unibe.ch/pig/HiRISE_IAF55.pdf
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mcaplinger
post Feb 16 2006, 10:14 PM
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QUOTE (jmknapp @ Feb 16 2006, 10:03 AM) *
Wondering what you are hinting at--perhaps this is targeted after one of the proposed Phoenix landing sites? The subpoint above is 75N 141W.


I think your software is confused, or ours is. What SPICE kernel are you using?


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jmknapp
post Feb 16 2006, 10:42 PM
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QUOTE (mcaplinger @ Feb 16 2006, 05:14 PM) *
I think your software is confused, or ours is. What SPICE kernel are you using?


Could be. Here are the kernels I'm using:

CK:
'$KROOT/ck/DESAT_MOI_sc_20060103171803.bc',

SPK:
'$KROOT/spk/spk_c_tcm1-od006_050812_060315_p-v1.bsp',
'$KROOT/spk/spk_moi_lowperf_t2_051123_060320_p-v1.bsp',
'$KROOT/spk/spk_moi_ideal_051123_060320_p-v1.bsp',
'$KROOT/spk/spk_moi_highperf_t1_051123_060320_p-v1.bsp',

I notice there's a big difference whether highperf, ideal or lowperf is used, so maybe that's the difference. The projection above uses highperf (since it's the last listed in the config file).


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mcaplinger
post Feb 16 2006, 11:31 PM
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QUOTE (jmknapp @ Feb 16 2006, 02:42 PM) *
I notice there's a big difference whether highperf, ideal or lowperf is used, so maybe that's the difference. The projection above uses highperf (since it's the last listed in the config file).


We were doing this planning several weeks ago, so the kernel I used was from mid-January. In those kernels, we were near periapsis at 6:00 UTC. Looks like we're looking at some replanning if the MOI performance makes this much difference. I would try rerunning with ideal and see what that looks like.

BTW, what software are you using for this?


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jmknapp
post Feb 17 2006, 02:00 AM
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QUOTE (mcaplinger @ Feb 16 2006, 06:31 PM) *
We were doing this planning several weeks ago, so the kernel I used was from mid-January. In those kernels, we were near periapsis at 6:00 UTC. Looks like we're looking at some replanning if the MOI performance makes this much difference. I would try rerunning with ideal and see what that looks like.

BTW, what software are you using for this?


Hmmm... using the "ideal" kernel gives periapsis on 15MAR2006 at 06:24UTC, 399km, at 67S 28E, although it's on the night side so the picture is dark. Pretty big difference there.

The software I'm using is a C program that I wrote to use the CSPICE library--so there could be a bug or three there. The same program works pretty well with Cassini, but at least in that case I have actual images to compare against for testing. Choice of kernels seems to be a big factor.

One kernel tells a cautionary tale:

spk_nomoi_051123_060320_p-v1.bsp

No MOI--gulp! That pessimistic kernel gives this view on 15MAR:



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