Chang'e 3 landing and first lunar day of operations, Including landing site geology and localization Options

[Thorsten Denk]

Interesting speculation by the LROC team about a possible landing place near crater Laplace A:

A Great Place to Rove!

Chang'E/Yutu could land about 10km south east, then (the rover) cross a wrinkle-ridge and reach the rim of the 8km crater.

Thorsten (this is my first name, Denk is the family name)

[PaulH51]

Interesting speculation by the LROC team about a possible landing place near crater Laplace A:
...A Great Place to Rove!...

Welcome Thorsten
During the Chinese cntv.cn coverage the commentators disused the landing site : the 'Bay of Rainbows'. Sinus Iridum is Latin for "Bay of Rainbows"

[tolis]

Looking at the lovely picture of Sinus Iridum a few posts back,
I wonder if the rim of the original crater is supposed to be
somewhere under the lava plain and whether the subsurface radar
of the rover could pick it up.

[Phil Stooke]

Yes, it would be under the plains, but probably too deep to be detected. I am more interested in a different possibility - there's a bright/dark boundary between two different mare units, best seen in Clementine data (I posted a false color version higher up the thread). If they land near the boundary and drive over it they may be able to detect the underlying unit beneath the overlying one and get the thickness of the top unit. In fact they may get thichnesses of multiple flow units.

Phil

[Phil Stooke]

This map shows the extent of the landing region, extending quite far outside Sinus Iridum as well as inside it, and the coverage by Chang'E 2 at about 1.5 m/pixel. When we know where the landing will take place I will be adding more maps to zoom in on the site.


PS - for scale, 5 degrees of latitude is 150 km.

Phil

[Explorer1]

Planning a 'Yutu route map' sticky thread Phil?
For what it's worth, the LROC team says they'll be photographing the site a few weeks after landing the 25th, January 22nd, and February 18th)
http://lroc.sese.asu.edu/news/index.php?/a...;.html#extended

[dvandorn]

Planning a 'Yutu route map' sticky thread Phil?

You know, that may not be a bad idea. Depending on the volume of images we get from the Chinese, it may be possible to follow the traverse somewhat real-time.

I would imagine we will have to wait to see if we get enough imagery to warrant it, but I'm beginning to think that we may need a dedicated Chang'e/Yutu folder, just as each of the Mars rovers has its own folder and LRO has its own folder, etc.

I am just on pins and needles waiting to see our first new lunar surface vista in decades!

-the other Doug

[Phil Stooke]

I guess I wasn't subtle enough! Yes, I am planning to map the route - whether in its own thread or not, and that may depend on image access. I am collecting material for a new Moon atlas and this will be part of it.

I will rely very much on our very helpful Chinese contributors for pointing out new articles and other information, translating names of features in the landscape etc.


Phil

[RichforMars]

This will be interesting. I remember seeing a long while ago the High definition video from the probe that went around the moon years ago. Good Stuff.

[dvandorn]

With today's imaging technology, I'm hoping for HD video from the lander of the landing itself, and also of Yutu deployment and operations.

-the other Doug

[tolis]

Yes, it would be under the plains, but probably too deep to be detected. I am more interested in a different possibility - there's a bright/dark boundary between two different mare units, best seen in Clementine data (I posted a false color version higher up the thread). If they land near the boundary and drive over it they may be able to detect the underlying unit beneath the overlying one and get the thickness of the top unit. In fact they may get thichnesses of multiple flow units.

Phil

So, Chang'e/Yutu will be landing/roving on top of a geologic sandwich.

[Cosmic Penguin]

Per latest Chinese reports:

Lunar landing is planned at 15:22-15:35 UTC on December 14.

The rover should be deployed from the lander at 20:38-22:21 UTC on the same day. Then some time within the communication window on December 15 at 07:21-15:38 UTC, the lander and rover will photograph each other and sing Moon River together during dating.

Source

[peter59]

At 9:24 pm, it was confirmed that Chang’e-3 had entered the new orbit.
http://www.asianews.co/change-3-probe-move...er-to-the-moon/
It seems that all is well.

[Phil Stooke]

Yes, only 15 km high at about 45 degrees north. Not long now.


Phil

[Phil Stooke]

Time for a rather trivial prediction. Unless Chang'E 3 lands at the far eastern end of the mapped landing area, the mountain Promontorium Laplace will be visible on the horizon, barring small-scale local obstructions. That will help to give an idea of the location of the landing site quite quickly.

Phil

[charborob]

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.

[kenny]

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...

[kenny]

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

[Thorsten Denk]

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

[Phil Stooke]

Very nice!

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

Phil

[Cosmic Penguin]

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).

[craigmcg]

Thanks Cosmic Penguin. Any update on the time coverage starts?

[pospa]

Thanks Cosmic Penguin. Any update on the time coverage starts?

and / or any published pictures from Moon orbit or the transfer?

[charborob]

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.

[Thorsten Denk]

Launch had a fantastic two-hours live coverage...

[kenny]

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.

[SpaceListener]

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.

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?

[kenny]

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...

[ollopa]

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.




That will be some view, come tomorrow evening, if................

[Astro0]

<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.

[PaulH51]

Anyone aware of any plans to live stream any of the Chang'e landing process from its mission control center (similar to the launch)

[bobik]

The best annotated diagram of the lander and rover I have seen so far...

The two features labeled as "fuel tanks" are actually "high-pressure gas cylinders" for pressurization of the pressure-fed propulsion system.

[Explorer1]

Any idea how low Earth will be in the sky to the cameras? Sinus Iridium is even farther from the sub-Earth point than Apollo 17 was, and I know it was lower in the sky from Taurus-Littrow than any of the other landing sites.
Also depends on how high the cameras can be pointed too!

[climber]

Anyone aware of any plans to live stream any of the Chang'e landing process from its mission control center (similar to the launch)

As usual, think of Emily's blog: http://www.planetary.org/blogs/emily-lakda...g-tomorrow.html

[PaulH51]

As usual, think of Emily's blog: http://www.planetary.org/blogs/emily-lakda...g-tomorrow.html

Many thanks

[kenny]

Any idea how low Earth will be in the sky to the cameras?

I estimate around 40 degrees above the horizon, based on the co-ordinates of the intended landing site.

[Astro0]

Live coverage is up and running on CCTV English edition.

[nprev]

Thanks, Astro0! (Stayed up all night since Ms. Nprev wanted a night on the town. Turns out that she can't drink NEARLY as much as me, so she's beddy-bye. Me, I GOT to see this happen!)

[Paolo]

from the map they showed on CCTV it looks like CE3 is heading to the eastern edge of the landing site, and into Mare Imbrium, close to crater Le Verrier instead of Sinus Iridum

[Paolo]

stealing borrowing a picture site from NASAspaceflight showing the targeted landing site

Attached thumbnail(s)

 

[Astro0]

Chang'e 3 on final descent.

[nprev]

Descent apparently proceeding well thus far. (Odd that there are also something like '7 minutes of terror' to do a lunar landing, just like a Mars landing...)

[jasedm]

Heart in mouth time!

Good luck all!

[Hungry4info]

Touchdown! A spacecraft is now transmitting data from the surface of the Moon!

[Astro0]

Touchdown!

[Seryddwr]

A flawless landing as far as I can see. Well done all!

[PaulH51]

TD about 2 minutes ago...... Image of ground and part of a landing leg....

[Paolo]

the rabbit has landed
in Mare Imbrium instead of Sinus Iridum

[nprev]

That was SMOOTH, and had frame-by-frame descent imagery as well! Congratulations to the PRC!!!!!

[Astro0]

Images from the descent. Amazing. Too fast to get enough shots to animate.

Here's one frame at about 70 metres (?)

[tolis]

And that, gentlemen, is how we do that..

[kenny]

From the big screen in Mission Control, it seems to have landed some way to east of Promontorium Laplace -- to be expected, given
it has landed one orbit earlier than the original discussions.

[Ian R]

GIF landing sequence:

http://postimg.org/image/l08n4q135/

[tolis]

Someone correct me if I am wrong, but I think their landing further east than sinus iridum may
have something yo do with the fact that they chose to land earlier (by 1.5 hr) and therefore the moon
hadn't yet rotated sufficiently to align sinus iridum with the probe's trajectory.

[nprev]

Gotta say that I'm pretty impressed. Hope that the rest of the mission goes even half this well because that was apparently a faultless descent.

Wow.

"We're BACK, baby!!!"

[Explorer1]

Woke up too late, thanks for the gif!
First surface images coming soon?

[tolis]

Correction on previous: it's 3.5 hours earlier. The Moon would have (not) rotated an extra ~2 deg or 60 km.

[Astro0]

Last frame from descent camera.

[tolis]

From the images taken from CCTV's live footage posted at the NASASpaceflight forum, it looks like it landed
near crater Laplace F, south of Montes Rectii.

[Paolo]

59 pictures were sent back in real time

[Paolo]

it looks like it landed near crater Laplace F, south of Montes Rectii.

seems to be in a flat area of Mare Imbrium between Laplace F and le Verrier

[Explorer1]

Live coverage over for now. Replaying landing....

[Cosmic Penguin]

The landing site is at 19.51 deg. West, 44.12 deg. North, per reports from the control center.

[Paolo]

thank you. that is 20-30 km southeast of Laplace F

[kenny]

Xinhua news agency has announced erroneously that “Chang'e-3 landed on the moon's Sinus Iridum, or the Bay of Rainbows, at about 9:12 p.m. Saturday,
making China the third country in the world to carry out such a rover mission after the United States and former Soviet Union.”

This is wrong location as the Mission Control panel screen showed it landing well to the east of Sinus Iridium, in Mare Imbrium.

My estimate of the landing coordinates, from the low-res screen, is in the area of 19 degrees West, 45 degrees North. That would put it about 25km SE
of the ~7km diameter crater Laplace F, near a ridge or scarp, and a couple of other craters of 2km diameter. So there might be some topography in view.

(written before previous announcements!)

[Paolo]

where is Phill Stooke when we need him!

[dilo]

Looking to the following CNTV screenshot, it seems that actual landing point is the rightmost one in the green box, presumably showing the previously selected potential landing area...

Attached thumbnail(s)

 

[Cosmic Penguin]

And the first image from the lander's monitoring camera.

(Source: Xinhua News Agency)

Attached thumbnail(s)

 

[ElkGroveDan]

Last frame from descent camera.

I don't suppose they named the descent camera 星期二 (Xīng qī èr)...

[volcanopele]

Any chance the landing site is in an existing LROC frame?

[Phil Stooke]

Very good chance, the whole area is blanketed with images, and Chinese scientists downloaded them all in that area (confirmed by LROC team) and will have chosen a site which is well imaged.

Phil

[Phil Stooke]

"where is Phill Stooke when we need him!"

Good day for the home internet to go down! Also real life is getting in the way, but I should be back in my protective bubble soon.

Phil

[4th rock from th...]

I break my long hibernation from this group to post a quick mosaic of some of the descent camera frames.
I corrected the proportions to have square craters.
There are some more distant frames that could cover a larger area.

[Hungry4info]

Well, I've identified the landing site.
Lat: ~44.1260, Lon: ~-19.5014.

Using http://target.lroc.asu.edu/q3/ and matching it to several of the descent camera images.
See below.

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[mcaplinger]

Well, I've identified the landing site.

Wow, nice work. Seems convincing to me.

[Paolo]

great work! so could the blocky crater we are seeing during the descent be the same one visible on that first surface pic?

[Hungry4info]

I think the crater from the surface image is actually a smaller one nearer the landing site. You can see it (and boulders in it that correspond fairly well to the surface image) in like the last frame before landing.
Edit: After looking at it again, I'm less certain of this.

[kenny]

This is the wider picture of the landing site, from Xinhua News Agency.

The crater which is 3 flag heights above the landing site is Laplace F.
The largest crater in the cluster to the west of the landing site is Laplace FA (at least, it is on my rather old Apollo-era US map).

[Hungry4info]

Candidate surface feature identifications.

Attached thumbnail(s)

 

[Steve G]

Candidate surface feature identifications.

Hello Old Friend, Long time no see!

[Explorer1]

Looking at the video on Emily's blog post, that very first image after landing is a little blurry in the shadows; that must've been the dust not quite settled. They sharpen in the next one:
https://www.youtube.com/watch?v=xfNb0jeTi2s

From 12:00 to 12:33 you can see it soften!
Not quite Curiosity style, but still really impressive (and presumably more images will come down soon)!

[tolis]

If the landing site ID posted by Hungry4info is correct,
the rover should find itself in a target-rich environment.

There are rocks and boulders of various sizes, especially along the rim of "the" large crater immediately to the west of the lander.
On the near side of that rim there is also a bright patch that may be ejecta from a small, fresh crater.

I wonder if the peaks of Montes Rectii are jutting above the N horizon Pole-Position style, ~100 km away.
That would be fun.

PS. The Pole-Position reference will only make sense to the more seasoned among you..

[Thorsten Denk]

Candidate surface feature identifications.

Interesting.
If you turn upside down (180deg) the picture at right (before landing),
and correct your assignment of "D", then it looks very convincing.

What size has this crater?

Thorsten

[Hungry4info]

The crater is 20 metres across and about 20 metres from the lander. And yeah, my D is off. Thanks for the correction.

[Thorsten Denk]

My "interpretation" of your findings.
Easier to see the coincidence.



Thorsten

PD: North is up.

[Hungry4info]

Nice work. That does make it easier to see!

[nprev]

Live feed from CCTV just started; rover roll-off to occur shortly.

http://english.cntv.cn/live/p2p/index.shtml

UPDATE: CCTV reports Yutu rover on the surface! No imagery yet.

[Explorer1]

Ramps being shown; rover shadow on left!

It's driving onto the ramp!

Crane lowering! Surface in background!

[Astro0]

Yutu on the ramp being lowered to surface.

[Explorer1]

Six wheels on Moon! Tracks!

[Astro0]

[nprev]

I watched the deployment (previously recorded). VERY interesting deployment method. Looked like it rolled forward onto the top of the ramp, which itself was subsequently lowered to contact the surface for roll-off. Don't we've seen a schema like that before.

[craigmcg]

Great coverage. HD res update every second.

[Hungry4info]

They showed the lander's area, presumably as imaged by the monitoring camera.

Attached thumbnail(s)

 

[Astro0]

Emily just posted an animation of Yutu driving onto the surface. As she says "Woohoo!".
http://www.planetary.org/blogs/emily-lakda...l-for-yutu.html

[Paolo]

my friend Tezio from the French "forum de la conquete spatiale" has authorized me to re-post here his amazing analysis of the landing trajectory of CE-3.
He assembled all the available images and took the center of each one, assuming the camera to be looking at the local vertical. The probe had no rotation at all. Only near the surface, it backed up and moved a bit to the right before touching down.

[kenny]

Wonderful piece of work.... It looks like the edge of large crater just a few tens of metres to the west of the landing site.

[infocat13]

shadow on the left so rover is facing south?

[kenny]

No, Rover drove off in the direction of north. Sun on right (east), and shadows on left (west) side.

[Phil Stooke]

No, facing north. It's morning, the sun is in the east, the shadow points west.

Phil