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Updates on Chang'e 3: Rover and lander both awake, good science data received

Posted by Emily Lakdawalla

14-01-2014 17:01 CST

Topics: mission status, the Moon, Chang'E program

UPDATE JAN 15 09:42 PT/17:42 UT: According to an unofficial Yutu rover account on Weibo (Chinese Twitter), the lander's main color camera did not survive lunar night. Thanks to @wylipei for the tip. Here is the text, two machine translations, and my attempts to decode them. The language reminds me of the "IKAROS-kun" persona for Japan's IKAROS mission on Twitter -- it's clearly less formal than official communications:

Original text: 三姐刚才和我说,她身上的地形地貌相机,月夜结束之后好像已经不能用了……虽然它早已经圆满完成了所有的预定任务,设计时也没有防护又冷又黑的月夜,但是真的坏掉了还是有点伤心,毕竟我的这些照片都是它拍的呢……现在姐姐又少了一双眼睛,肯定更寂寞了,你们别光顾着画我,也要给她画几张画儿哦!

Google translation: Third Sister and I said just now, topography camera on her, and after the end of Moonlight seems to have not used ...... though it had already successfully completed all scheduled tasks, there is no protection in the cold and dark moonlit design, but true is broken or a little sad, after all my photos are taken of it ...... and now its sister one less pair of eyes, and certainly more lonely, and you do not just draw me, but also to the children she painted several paintings Oh!

Baidu translation: My sister just now and I said, her topography camera, the night after the end seems to have not used...... Although it has already accomplished the scheduled task all, design also not defend cold and dark night, but really broken or a little sad, after all my photos are taken...... Now my sister and little eyes, certainly more lonely, you don't draw me, also want to draw some pictures for her!

My translation: My sister Chang'e 3 just told me that after the night ended, the topography camera seems not to be working.....although it had already successfully completed all scheduled tasks, and wasn't designed with any protection to survive the cold and dark of the lunar night, I'm still a little sad it's broken, after all it took all the photos of me on the Moon. And now my sister has one less pair of eyes, it feels more lonely, that she can't "draw" me. I want to draw pictures for her! [Maybe: I want to see for her?]

Jan 14 report:

According to news reports from China, the Yutu rover woke up from its two-week nap at 5:09 Beijing time on January 11 (21:09 on January 10, UTC), successfully establishing communication with Earth. That means its folding solar panel and the camera mast have both re-deployed following their stowage in preparation for hibernation. Yay! The lander woke up autonomously at 8:21 Beijing time / 00:21 UTC on January 12, and is also "in normal condition." The news of the rover's wakeup was circulating on the Internet this weekend, but I held this update until I saw confirmation that the lander had also been heard from.

A state television report posted today says that today Yutu completed its first "exploration of the lunar soil" but didn't provide much in the way of specifics about what that meant. The report does contain a video shot from mission control on January 12, with the giant screen showing the position of the rover.

What's next for the mission? Science for the lander, and driving for the rover. Phil Stooke, who has been mapping the rover's peregrinations so far, says he's read that the rover can drive upwards of 200 meters per hour, pausing every 7 to 10 meters for imaging for autonomous hazard avoidance.

I wanted to post here a couple of higher-resolution versions of two of the images I posted last week. These are much, much bigger than the ones I originally posted. Here's the first image returned from the lander -- click through twice to enlarge to its full glory:

First images of lunar landscape from Chang'e 3 lander, December 15, 2013

Chinese Academy of Sciences

First images of lunar landscape from Chang'e 3 lander, December 15, 2013

And here is the view of Earth from the lander:

Earth from Change'3

Chinese Academy of Sciences

Earth from Change'3
The Chang'e 3 lunar lander captured this photo of Earth from the lunar surface on December 25 at 2:15 China time (December 24 at 18:15 UTC).

I had a nice email from Justin Rennilson, who worked for many years in the imaging lab at JPL, telling me that the photo of Earth reminded me of the very first photo ever taken of Earth from the lunar surface, by Surveyor 3. The fact that the two show Earth at a similar phase is no coincidence: in both cases, the landers touched down a little bit after sunrise at their respective landing sites, which means that Earth appeared to both Chang'e 3 and Surveyor 8 (and indeed most other lunar landers) as a waning crescent in the sky. Lunar noon comes when Earth appears "new", and the waxing Earth tells a lunar lander that lunar night is arriving.

First image of Earth from the surface of the Moon: Surveyor 3


First image of Earth from the surface of the Moon: Surveyor 3
On April 30, 1967, the Surveyor 3 lander took the first photo of Earth from the lunar surface. Lunar Orbiter had taken the first photo of Earth from lunar orbit just 8 months previously.
Context for Surveyor 3's photo of Earth from the lunar surface
Context for Surveyor 3's photo of Earth from the lunar surface

The new, high-res versions of those Chang'e 3 images came from this post on the Chinese Academy of Sciences website, a link sent to me by Yong-Chun Zheng. I asked him about the copyright on the images, and he told me that I can share them with attribution (to the Chinese Academy of Sciences), for non-commercial purposes. So I still don't know what to tell publishers about whether they can use them, but please feel free to download them for personal and educational use.

That post, and a couple of other pages on the Chinese Academy of Sciences website, contained some results from the various science instruments. First, here's a quick summary list of the instruments, with some details cribbed from the spaceflight101 website:

Lander instruments

  • Three color "topography cameras" for terrain imaging
  • Descent camera (1280x1024 pixels)
  • Near-ultraviolet telescope (wavelength range 245 to 340 nanometers) for stellar observations down to 13th magnitude
  • Extreme ultraviolet camera for observing Earth's plasmasphere

Rover instruments

  • Two color panoramic cameras for stereo imaging
  • Two mast-mounted navcams and two forward-facing hazcams
  • Ground-penetrating radar (to depths of 30-100 meters)
  • Alpha particle X-ray spectrometer
  • Visible / near-infrared imaging spectrometer

The images shown above are from the lander's topography camera, which appears to have a full resolution of 2354 by 1728 pixels. And you've seen lots of images from its descent camera.

Next, here's a photo of the constellation Draco as seen by the lander's near-ultraviolet telescope.

Stars in Draco as seen from Chang'e 3's near-ultraviolet telescope

Chinese Academy of Sciences

Stars in Draco as seen from Chang'e 3's near-ultraviolet telescope

A key to the numbered stars:

Star numbernamenumbername
1 HD 151044 13 TYC 3505-598-1
2 HD 151387 14 HD 234341
3 HD 234351 15 IDS 16429+5037
4 TYC 3505-184-1 16 HD 234344
5 HD 234343 17 HD 234349
6 HD 234331 18 TYC 3503-567-1
7 TYC 3506-1864-1 19 TYC 3505-650-1
8 TYC 3505-398-1 20 TYC 3506-1008-1
9 TYC 3506-1196-1 21 TYC 3502-795-1
10 TYC 3505-138-1 22 TYC 3506-1242-1
11 HD 151444 23 TYC 3505-329-1
12 TYC 3505-328-1    

Here's an ultraviolet view of Earth. I posted something similar on Friday, but I learned from the Chinese Academy of Sciences website that what I posted was actually a computer simulation of what Earth's plasmasphere should look like from the lander's extreme ultraviolet camera. This image is the actual data from the camera. (I've corrected my original post.)

Earth in the ultraviolet from Chang'e 3

Chinese Academy of Sciences

Earth in the ultraviolet from Chang'e 3
The extreme ultraviolet camera on Chang'e 3 studies the plasma environment around Earth at a wavelength of 63 nanometers. This image was taken shortly after Chang'e 3's landing, on December 16, 2013.

And here is the model, to compare to the data.

Model of Earth's plasmasphere in the extreme ultraviolet as seen from Chang'e 3

Chinese Academy of Sciences

Model of Earth's plasmasphere in the extreme ultraviolet as seen from Chang'e 3

So that rounds out the lander instruments. As for the rover instruments, my previous post contains photos from the panoramic camera (of the lander), and what seem to be navigational camera images (providing the black-and-white "donut" view around the rover).

Next up is the ground-penetrating radar. These images are exceedingly tiny; there's no click-to-enlarge because this is as big as it gets. I believe that the two different profiles represent the radar's two different frequencies, which should theoretically access different depths in the soil. I won't hazard any attempt at interpretation of these profiles, but it's nice to see that the instrument appears to be working and is detecting some kind of reflections.

Ground-penetrating radar data from Yutu's first lunar day

Chinese Academy of Sciences

Ground-penetrating radar data from Yutu's first lunar day

Next is the alpha-particle X-ray spectrometer. According to the Chinese Academy of Sciences, the APXS took a calibration measurement of a basalt standard on December 23, and its first measurement of lunar soil on December 25. "An initial analysis indicates that eight major rock-forming elements (Mg, Al, Si, K, Ca, Ti, Cr and Fe) and at least 3 minor elements (Sr, Y and Zr) of the Moon can be identified in this spectrum."

Yutu first APXS measurement of lunar soil

Chinese Academy of Sciences

Yutu first APXS measurement of lunar soil

Finally, there is the visible and near-infrared imaging spectrometer. The spectrometer provides an image of the lunar soil that's not as sharp, spatially speaking, as what you can get from a camera, but the multicolored cubical sides to this diagram show you that at every single pixel in the image, there is detailed spectral information across 100 different visible and near-infrared wavelengths.

Yutu first visible/near-infrared spectrometer image of lunar soil

Chinese Academy of Sciences

Yutu first visible/near-infrared spectrometer image of lunar soil

Here are two example spectra, one each from the visible and near-infrared channels. You can see that in visible wavelengths, the spectrum is a slightly red one, sloping gently upward from 450 (blue) to 700 (red). Then it reaches a peak and slopes gently downward to a minimum at about 950 nanometers, followed by a barely perceptible local low at about 1900-ish nanometers -- those are the hallmarks of the mineral pyroxene's presence in the lunar soil.

Yutu visible/near-infrared spectra of lunar soil

Chinese Academy of Sciences

Yutu visible/near-infrared spectra of lunar soil
The top graph is a spectrum from the visible channel, the bottom graph a spectrum from the near-infrared channel.

All of these data and images were taken on the first lunar day. I haven't seen anything new from the second lunar day yet; I will post them when I find them!

Finally, I'll end this post with a neat artwork from Don Davis: Yutu watching the sunrise. Don says he produced this about when the depicted moment was happening on the Moon.

Sunrise on Yutu

Don Davis

Sunrise on Yutu
This is an artist's concept of the slow lunar sunrise on the Chang'e 3 rover. The faint inclined glow in the sky is the Zodiacal light, made of sunlit fine particles forming a flattened lens-shaped mass along the plane of the planets' orbits.
See other posts from January 2014


Or read more blog entries about: mission status, the Moon, Chang'E program


Anonymous: 01/14/2014 08:14 CST

I tried the link you gave, but it's not obvious how to access all the "new hi-res versions of Chang'e 3 images you mentioned above: - how so?

Emily Lakdawalla: 01/15/2014 12:07 CST

The only two higher-res ones are the ones I included in this post. There are no click-to-enlarge links in any of the CAS posts. However, if you right-click and save the embedded images, you'll find that it's common for them to be embedded in the web pages at a lower resolution than their actual size. That's how I found the higher-resolution versions -- they're right in front of you, they're just being displayed smaller than actual size.

Kurt Retherford: 01/15/2014 02:49 CST

Nice post! Thanks for the update regarding the Extreme Ultraviolet Camera. We were scratching our heads about that one. Note that this is an image of mainly 30.4 nm emission from helium ions in the plasmasphere, e.g., as described on your link to spaceflight101. But your caption says something about 63 nm. Perhaps this is a long wavelength cutoff to the camera filter? Yutu is certainly producing a rich dataset and we look forward to more to come.

wlypei: 01/15/2014 08:16 CST

The last sentence means: you(Yutu followers) do not just draw me(cartoon), you should draw more cartoons of her(Chang'e 3 lander)! This unofficial weibo is very cute and funny. :-)

Emily Lakdawalla: 01/16/2014 10:10 CST

Aha! I had seen the drawing that the unofficial weibo posted right before this statement. I tried to translate the text from that, but I couldn't quite make sense of it. Yutu seemed annoyed by the fact that they hadn't put enough clothes on her to be exploring the Moon!

Huajun Gu: 01/16/2014 10:43 CST We have a 30 minutes video on air yesterday.

helen: 01/19/2014 07:46 CST

Did the Chinese find any Helium3 as claimed by the Americans in the Sixties?

Albert Abdrakhimov: 01/20/2014 03:25 CST

I found flash animation of POCKN ( of Panorama Dec.18, 2013

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