Emily LakdawallaJan 14, 2014

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

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.

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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:

And here is the view of Earth from the lander:

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.

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.

A key to the numbered stars:

Star numbernamenumbername
1HD 15104413TYC 3505-598-1
2HD 15138714HD 234341
3HD 23435115IDS 16429+5037
4TYC 3505-184-116HD 234344
5HD 23434317HD 234349
6HD 23433118TYC 3503-567-1
7TYC 3506-1864-119TYC 3505-650-1
8TYC 3505-398-120TYC 3506-1008-1
9TYC 3506-1196-121TYC 3502-795-1
10TYC 3505-138-122TYC 3506-1242-1
11HD 15144423TYC 3505-329-1
12TYC 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.)

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

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.

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."

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.

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.

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.

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