Targets for LRO |
Targets for LRO |
Guest_Zvezdichko_* |
Jul 17 2009, 09:45 AM
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#106
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Guests |
Well, this will still allow us to see something
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Jul 17 2009, 12:48 PM
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#107
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
But assuming 1.2 meter/pixel at the 120km altitude, the LM Descent Stage and its shadow should be defined by no less than 70 pixels. The LEM is approx 4.5 metres across. At 1.2m/pixel - that's 3-4 pixels across, a total of perhaps 16 pixels of LEM. Assuming a height of 4 meters ( which is generous) - and illumination at 10 degrees - the shadow will be another 17 or so pixels long. Doug |
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Jul 17 2009, 02:30 PM
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#108
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Member Group: Members Posts: 150 Joined: 3-June 08 From: McLean, VA Member No.: 4177 |
Your calculations are close. The LM structure is 4.22 m across, but footpad edge to footpad edge (still bright Kapton?) is 9.45 m. I would add the gear to show up as another pixel at least making the LM 25 pixels (5 ^2). The top of the LM Descent Stage structure is 3.18 m but the tops of the plume deflectors are at 4.23 m. So the shadow trig has it from 18 to 20 meters long. So 17 or slightly fewer pixels not squared but maybe a third of that is at least 75 pixels. So I revise my estimate upwards: the LM will be defined by at least 100 pixels.
Then there will be extra flotsam like the brightly lit backpacks and other things. We'll know soon! EDIT: of course I'm neglecting slant range: this all assumes LRO was nearly right above the site when the pic was taken. |
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Jul 17 2009, 02:53 PM
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#109
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
Oh - ok - you were counting ALL the pixels. Anyway - I started a new LRO thread for Apollo sites - we'll need it in about an hour or two hopefully
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Jul 17 2009, 03:01 PM
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#110
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Senior Member Group: Members Posts: 1465 Joined: 9-February 04 From: Columbus OH USA Member No.: 13 |
EDIT: of course I'm neglecting slant range: this all assumes LRO was nearly right above the site when the pic was taken. Since the ground tracks on successive passes are about 30 km apart, and the vantage point is 120 km high, I suppose there needn't be much slant (15/120 = 7 degrees). -------------------- |
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Jul 18 2009, 08:31 AM
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#111
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Member Group: Members Posts: 233 Joined: 21-April 05 Member No.: 328 |
John Moore, thanks for link to details on Arecibo radar mapping of the Moon's poles. So, there was no magic involved -- Arecibo had the same oblique view that we do, and as a result was only able to examine 25% of the craters' permanently shadowed areas -- and obviously not the deepest areas. Thus, as someone else mentioned, there is still hope that real "hit it wth a pickaxe" ice can be found on the moon -- lunar gold!
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Jul 18 2009, 10:45 AM
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#112
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Member Group: Members Posts: 156 Joined: 22-May 09 From: Ireland Member No.: 4792 |
Re: Arecibo + radar.
Glenn, you're welcome...had been reading up on it just a week earlier, so it was close to hand John |
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Guest_Zvezdichko_* |
Jul 19 2009, 02:57 PM
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#113
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Guests |
Uh... what happened to the other thread?
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Jul 19 2009, 03:26 PM
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#114
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Solar System Cartographer Group: Members Posts: 10151 Joined: 5-April 05 From: Canada Member No.: 227 |
Yes, I was wondering that... but it's back now...
Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Jul 21 2009, 01:30 AM
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#115
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Member Group: Members Posts: 233 Joined: 21-April 05 Member No.: 328 |
Given that the main goal of LCROSS is to search for water ice at the moon's south pole, I suppose this is an appropriate place for the following comment, namely, that the success of said search -- and I am not predicting here that it will be successful -- will pretty much end the Mars vs. Moon debate in respect to which of the two receives our next big push. But that becomes another topic for another time and place . . .
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Aug 5 2009, 11:55 AM
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#116
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Member Group: Members Posts: 150 Joined: 3-June 08 From: McLean, VA Member No.: 4177 |
I made an animation of the LRO passes over the Apollo 11 site, using the "mission baseline v8" data given at http://lroc.sese.asu.edu/downloads.html. They updated the file to v10. It looks like it tracks pretty closely with the imaging data now. |
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Aug 5 2009, 12:13 PM
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#117
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Senior Member Group: Members Posts: 1465 Joined: 9-February 04 From: Columbus OH USA Member No.: 13 |
They updated the file to v10. It looks like it tracks pretty closely with the imaging data now. I downloaded the v10 files and indeed it tracked well, differing from the position given by http://lroc.sese.asu.edu/whereislro/ by only a few minutes. BTW, the "Where is LRO" site now seems to be gone (check link). So the question becomes "Where is Where is LRO?" I hear that up-to-date SPICE kernels are provided to the various centers on a daily basis but those aren't available to the public. That contrasts to, say, MRO, where updated files are continually posted to the NAIF public website, including both planned and as-flown instrument pointing files (so-called CK kernels). Cassini also does this. My understanding is that the older programs (particularly Cassini, being an old-school big budget project) were more committed to this. In Cassini's case, they even provide "science plan" kernels containing text information about the type and purpose of observations, correlated with instrument command sequences. Eventually the pointing and trajectory files will be posted to the PDS, but only after 8 months or something like that. So near real time for LRO looks to be a no go, as far as the public is concerned. -------------------- |
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Aug 5 2009, 03:19 PM
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#118
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Member Group: Members Posts: 150 Joined: 3-June 08 From: McLean, VA Member No.: 4177 |
I have no idea how much effort it takes to keep going something like "Where is LRO." I would think it would be trivial: just point some telemetry or tracking data at an automatic web thingy and off you go.
I wish NASA would, as a matter of course, maintain an up to date data stream of a mission's state vector and attitude. They could have a standard web protocol and each mission's data folks would plug those 9 numbers in with a time stamp (every minute or second) and we could all do with it what we wanted. We would know where pics were taken from instantly and, where there are interesting mission events, simulate them if we have the skill or interest. Planetariums could fly along with some missions - landers would be especially fun to follow in "real" time. |
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