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Chang'e 3 landing and first lunar day of operations, Including landing site geology and localization
charborob
post Dec 12 2013, 03:59 PM
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According to my rough calculations, Promontorium Laplace should be visible from about 95km away. If Chang-e 3 lands near the mare ridge S-E of Laplace A, Prom. Laplace would barely be jutting above the horizon.
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kenny
post Dec 12 2013, 04:09 PM
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QUOTE (Phil Stooke @ Dec 12 2013, 02:43 PM) *
Time for a rather trivial prediction.


Hardly trivial, Phil, given the time you have spent staring at hill tops to determine the uncertain location of Luna 9, in this same quadrant of the moon!

I look forward to seeing the summit of Promontorium Laplace on Saturday...
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kenny
post Dec 12 2013, 04:20 PM
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This is orbital view of Promontorium Laplace taken by Apollo 15 from the South-South East (looking NNW), over the crater Helicon.

Promontorium Laplace from the SSE

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Thorsten Denk
post Dec 12 2013, 10:00 PM
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Sunrise in Sinus Iridum!

I'm not an astrophotographer, but I couldn't resist to take some pictures.
(18:54 UTC, downsized to 50% and cropped, original here.)



I was surprised how incredibly fascinating it is to be able
to see with my own eyes (and a 10"-Dobson) the operation area
of a human rover on another celestial body!
Laplace A and the wrinkle ridge were easily visible.

Go, Chang'E! Your landing area is now in sunlight!

Thorsten
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Phil Stooke
post Dec 12 2013, 10:05 PM
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Very nice!

Joel Raupe, on Lunar Networks reports rumours that the landing site will be in the area shown here.

Phil

Attached Image




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... because the Solar System ain't gonna map itself.
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Cosmic Penguin
post Dec 13 2013, 08:18 AM
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Per latest Chinese reports the landing time has shifted to ~13:40 UTC (~8:40 am EST/5:40 am PST/9:40 pm in Beijing).


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UMSF - the place of Opportunity to satisfy your Spirit of Curiosity
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craigmcg
post Dec 13 2013, 01:13 PM
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Thanks Cosmic Penguin. Any update on the time coverage starts?
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pospa
post Dec 13 2013, 01:33 PM
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QUOTE (craigmcg @ Dec 13 2013, 02:13 PM) *
Thanks Cosmic Penguin. Any update on the time coverage starts?

and / or any published pictures from Moon orbit or the transfer?
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charborob
post Dec 13 2013, 01:59 PM
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I would be surprised if there were any live coverage, considering how secretive the Chinese are. We'll get an announcement after the landing has occurred, and, I hope, a couple of pictures, but I'm not holding my breath.
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Thorsten Denk
post Dec 13 2013, 02:08 PM
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Launch had a fantastic two-hours live coverage...
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kenny
post Dec 13 2013, 02:24 PM
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I really don't think the Chinese are anything like as secretive as they once were. They showed great live coverage of launch and trans-lunar injection on TV.
They have announced in advance a revision of the landing time from 15:35 UTC to 13:40 UTC, so have brought it forward by one orbit.
I think there will be live or near-live coverage on Chinese CNTV. Although there is to be a descent imager snapping away as it lands, that is supposed
to be for planning rover routes, so I doubt if those will be streamed live, and will probably be sent back after the autonomous landing.
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SpaceListener
post Dec 13 2013, 05:01 PM
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I suppose mostly as Kenny says. Sure Chinese government will announce and show with great detail if the mission was successful and a few words and no images if it fails. Hope that the Saturday would be a great day. smile.gif

The Perilunar orbit of Change'e-3 is of polar orbit from south to north would be above of the Laplace crater at around 43:42 North & 26:56 West? or its perilunar would be at lower latitude such as by 30:00 North in order to take a braking trajectory before landing on Moon?
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kenny
post Dec 13 2013, 07:05 PM
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Chang’e 3 is now in an intermediate descent orbit of 15 x 100 km, which is of very similar altitude parameters to the descent orbit used by Apollo in the 1960s
and 70s. However, Chang’e is attempting a landing out of a near-polar orbit (90 degrees inclination), which has never been performed before by any spacecraft.

According to Patrick Blau at Spaceflight101, about one hour ahead of the start of the landing sequence (i.e. half an orbit earlier on the far side of the moon),
Chang'e 3 makes an engine burn to further reduce its periselene altitude to just 2 km above Sinus Iridum. This is an extremely low orbit – Apollo regarded a
powered descent start of lower than 16 km as a safety hazard, but I guess we know a lot more about mascons and their orbital perturbations now.

According to Astrogatorsguild web site, it seems the landing is on the southward-travelling portion of the orbit, so it will come in from over the North Pole and start its final
braking over Sinus Iridium. Then it will take 700 seconds from ignition at 2,000 metres altitude down to landing.

Lovely view of the moon this afternoon over Loch Ness, with the terminator already west of Sinus Iridium, and the bay and Promontory Laplace in sunlight,
ready and waiting...
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ollopa
post Dec 13 2013, 09:16 PM
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Many thanks to Cosmic Penguin and others for the hard information. However, is it just me or is the S/N ratio deteriorating elsewhere on this thread?

A propos Phil's far-from-"trivial prediction": there may be something in the way of that view of Promontorium Laplace.

A fascinating paper (in Chinese, so I'm relying on the pictures) appeared last month in Scientia Sinica: "Geological features and magmatic activities history of Sinus Iridum".

Scientia Sinica

I believe it is fair use to post the LRO/LOLA-based elevation map for the wrinkle ridge near where most people now think Chang'e will land.

Attached Image



That will be some view, come tomorrow evening, if................
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Astro0
post Dec 14 2013, 05:00 AM
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<ADMIN MODE>

From comments in a few recent posts, I just want to remind people to avoid making statements which may imply any political (and I mean that in its broadest sense) commentary about the merits or otherwise of the openness or otherwise of any particular nation's space program, government or media.

As with ANY mission, what data/images are released are a bonus to the public (that includes UMSF'ers) not a right.

</ADMIN MODE>

Just enjoy the ride. smile.gif
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