Dawn approaches Ceres, From opnav images to first orbit |
Dawn approaches Ceres, From opnav images to first orbit |
Feb 12 2015, 07:35 PM
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#301
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Member Group: Members Posts: 112 Joined: 31-January 15 From: Houston, TX USA Member No.: 7390 |
Dawn's main antenna appears to be facing towards Earth right now with no gentle thrusting from the engines. I'm assuming more data is coming down...
BTW, I still see the northern hemisphere as brighter and less contracted than the southern hemisphere. The southern hemispehere seems to be more cratered and more excavated. But, I'm sure that will all change when we get better views. Andy |
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Feb 12 2015, 07:44 PM
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#302
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Member Group: Members Posts: 334 Joined: 11-December 12 From: The home of Corby Crater (Corby-England) Member No.: 6783 |
QUOTE If we weren't allowed to speculate than this forum would be quite a bit smaller! Today makes the beginning of an exciting week for the Dawn mission. Like was explained a couple pages back, from today to the 19th, Ceres is going to triple in resolution. Triple the resolution = one third speculation. Right! Or is it, triple resolution = 3x speculation?? Maths was never my strong point! |
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Feb 12 2015, 09:00 PM
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#303
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Senior Member Group: Members Posts: 4252 Joined: 17-January 05 Member No.: 152 |
I think it scales with the number of pixels. So triple the resolution means 9x the speculation!
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Feb 12 2015, 10:35 PM
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#304
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Member Group: Members Posts: 715 Joined: 3-January 08 Member No.: 3995 |
Or to paraphrase Thomas Edison, it's 1% resolution and 99% speculation.
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Feb 12 2015, 10:39 PM
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#305
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Member Group: Members Posts: 288 Joined: 28-September 05 From: Orion arm Member No.: 516 |
OPNAV3 hasn't been acquired yet. Imaging won't until later this evening, MST. From looking at Celestia, the observations times are (keep in mind that these are just the dwell times, the actual time frame when images are actually being taken is likely shorter and in the middle of these times frames): Footprint 1: 2015-035 02:13-07:21 UTC Footprint 2 (centered on Ceres): 2015-035 07:30-10:47 UTC Footprint 3: 2015-035 10:56-14:35 UTC The HGA is pointed toward Earth between 2015-0a35 15:53-2015-036 07:44 UTC (again, it might not be downlinking that entire time) Meanwhile any times of todays imaging session RC1 and transmission available? |
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Feb 12 2015, 11:44 PM
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#306
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Member Group: Members Posts: 334 Joined: 11-December 12 From: The home of Corby Crater (Corby-England) Member No.: 6783 |
QUOTE I think it scales with the number of pixels. So triple the resolution means 9x the speculation! I'll drink to that!! |
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Feb 13 2015, 02:44 AM
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#307
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
While eagerly awaiting the new images, here another processing of the Ceres OpNav3 sequence pia19179-16.gif, animated, and as tiles:
-- some remote similarity to the DLR version. Regarding surface reflectance: Approximately describing Ceres' surface reflectance needs far more sophistication than a matte Lambertian description of an ellipsoid. A modified Lambertian description of an ellipsoid with a reflectance of about (cos phi) ^(0.7) for phi the angle between ellipsoid surface normal and Sun resulted in the best - but not in a good approximation - (for gamma = 2.2) thus far. |
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Feb 13 2015, 04:17 AM
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#308
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Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Those are incredible.
It is nice that we can finally start studying a large ellipsoid besides Iapetus. And we don't know very much about Iapetus! |
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Feb 13 2015, 09:46 AM
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#309
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Senior Member Group: Members Posts: 1089 Joined: 19-February 05 From: Close to Meudon Observatory in France Member No.: 172 |
WOW ! WOW ! WOW ! Thanks a lot Gerald !
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Feb 13 2015, 11:59 AM
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#310
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Member Group: Members Posts: 423 Joined: 13-November 14 From: Norway Member No.: 7310 |
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Feb 13 2015, 12:02 PM
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#311
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Member Group: Members Posts: 813 Joined: 29-December 05 From: NE Oh, USA Member No.: 627 |
Looks like DAWN downlink is in progress as of 06:57am EDT.
http://eyes.nasa.gov/dsn/dsn.html What a week ahead coming... DAWN Ceres RC1 and navcams from Rosetta 6 km 67P/CG flyby! Craig |
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Feb 13 2015, 03:08 PM
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#312
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Senior Member Group: Moderator Posts: 3234 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
Meanwhile any times of todays imaging session RC1 and transmission available? Sorry, I've been busy with Rhea that last couple of days. Here are those times FC Stare at Ceres: Feb 12, 2015 07:22:00 - Feb 12, 2015 21:45:25 UTC The HGA is pointed toward Earth between Feb 12, 2015 22:44:58 - Feb 13, 2015 17:44:22 So the spacecraft will begin its turn back toward its thrusting orientation in approximately 2 hours, 36 minutes from this post. Maybe images will show up today online, but my money is on Monday. -------------------- &@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io |
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Feb 13 2015, 04:29 PM
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#313
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Member Group: Members Posts: 495 Joined: 12-February 12 Member No.: 6336 |
Yes most likely on Monday, the personell on the MaxPlanck institute should have left for the day at this hour now since it is Friday. But I could imagine one or two have hanged around for a first peek anyhow. That unless some of the NASA guys hijack an image or two (joking), I noted that Goldstone have taken over from Madrid for Dawn transmissions now.
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Feb 13 2015, 07:52 PM
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#314
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Member Group: Members Posts: 656 Joined: 20-April 05 From: League City, Texas Member No.: 285 |
...another processing of the Ceres OpNav3 ... Gerald, this is some really impressive processing you're doing. I hope you write-up your methodology some day, I would like to have an educated basis for doing something similar (though how many firsts like this will we have?). Really gives a sense that there has been some major resurfacing of the northern hemisphere extending well into the southern hemisphere, or alternatively that there is a remnant unsurfaced region in the southern hemisphere. I haven't had this much fun since Spirit & Opportunity landed |
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Feb 13 2015, 08:08 PM
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#315
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IMG to PNG GOD Group: Moderator Posts: 2251 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Really gives a sense that there has been some major resurfacing of the northern hemisphere extending well into the southern hemisphere, or alternatively that there is a remnant unsurfaced region in the southern hemisphere. Craters are much more difficult to see in the northern hemisphere at this resolution due to the higher sun angle - I see no clear evidence of major resurfacing in the northern hemisphere. The biggest craters might be in the southern hemisphere though. What's happening will be revealed in the higher resolution images to come - waiting for the new RC1 images is remarkably difficult. |
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