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Chang'E 2 imaging of Toutatis succeeded beyond my expectations!

Posted by Emily Lakdawalla

14-12-2012 17:59 CST

Topics: near-Earth asteroids, pretty pictures, asteroids, asteroid 4179 Toutatis, Chang'E program, global views

The Chang'E 2 mission flyby of Toutatis succeeded in acquiring images. Oh my goodness, did they succeed. This is awesome.

Chang'E 2 images of Toutatis

Chang'E 2 images of Toutatis
The closest fly-by was at 08:30:09 UTC on December 13 at an altitude of just 3.2 km and at a relative velocity of 10.73 km/s. Quite a few photos were snapped by the CCD camera - including this series of photos taken 93 - 240 km away from Toutatis:

The images are much better than I expected them to be. There are also many more of them than I expected. I look forward to learning more about how they were acquired!

These, in combination with the incredible radar images still being acquired from Goldstone and innumerable optical observations, make Toutatis one of the best-studied asteroids in the solar system.

I'll have more to write about this in the future, but I wanted to share the news as soon as I heard it! Today, we need good news.

Here is a CCTV report on the encounter -- in Chinese, obviously, so all I get is "Chang-E," but the images in it are cool.

Many thanks to users yaohua2000 and Cosmic Penguin at unmannedspaceflight.com for bringing this to Western attention! Yaohua2000 also provided the following summary of the encounter:

Relative speed at 10.73 km/s
Closest flyby at 3.2 km altitude

Sequence (local time):
• Dec13 15:25 Return solar panels to 180 degrees
• Dec13 15:30 Switch to inertial altitude control
• Dec13 15:45 Switch to star orientation 10
• Dec13 15:48 Switch to star orientation 2
• Dec13 16:20 Solar panel monitoring camera power up
• Dec13 16:30 Closest flyby
• Dec13 16:45 Solar panel monitoring camera power down

Attached image: captured at 93–240 km distance between 16:30:09–16:30:24, maximum resolution 10 meters/pixel

 
See other posts from December 2012

 

Or read more blog entries about: near-Earth asteroids, pretty pictures, asteroids, asteroid 4179 Toutatis, Chang'E program, global views

Comments:

Guillermo Abramson: 12/14/2012 06:28 CST

Excellent news! Congratulations to the Chang'E people and all the Chinese!

Keith Hearn: 12/14/2012 07:18 CST

Very impressive. The scientists and engineers involved should be very proud, especially considering that Chang-E wasn't designed to do this sort of imaging. My hat is off to them.

Ethan Walker: 12/14/2012 09:01 CST

Awesome! these sorts of mission extensions also show that China's exploration program is maturing rapidly. I was wondering though about the color. I might expect a slightly reddish color, but that is really quite pronounced. I'm surprised Chang'E was even equipped with a color camera!

Andrey Mezentsev: 12/14/2012 09:10 CST

Quite acceptable, congratulations!

Emily Lakdawalla: 12/15/2012 09:02 CST

Given the sheer quantity of images, I am assuming we are seeing photos shot using the webcam-style cameras they used to monitor rocket firings and solar panel deployments (see http://www.planetary.org/blogs/emily-lakdawalla/2010/2774.html -- and I notice I have some import errors to clean up in that post.)

Mark Adler: 12/15/2012 10:12 CST

I also picked up the word TOOO-tah-teess in the Chinese broadcast.

RanJones: 12/16/2012 07:42 CST

Hearty congratulations to the scientists and engineers who pulled this off with grace and aplomb! 3.2 km altitude! My gosh. :-)

pigi.cn: 12/16/2012 10:20 CST

I saw the good news today, and I can tell you that the photo was captured by a small color camera witch used for monitor solar cell status. Wonderful pic! Thanks for the engineer,it is really not easy!

pigi.cn: 12/16/2012 10:20 CST

I saw the good news today, and I can tell you that the photo was captured by a small color camera witch used for monitor solar cell status. Wonderful pic! Thanks for the engineer,it is really not easy!

ghh1: 12/16/2012 08:52 CST

My translation from the Chinese news segment: China's National defense industrial agency today announces a new breakthrough in China's lunar and space exploration. CE-2 has successfully executed a close fly-by of the Toutatis asteroid at a distance of approximately 7 million km from earth; this is the first time any nation has made such close examination of the asteroid. This breakthrough also signifies that China is the fourth country, after the US, the ESA, and Japan, which has the capability to explore asteroids. At 1630 on December 13, CE-2 responded to commands and approached and made a close fly-by of the Toutatis asteroid. Relative speed was 10.73 km/s; closest distance was 3.2 km from the asteroid. CE-2 used its on-board star observation cameras to capture images from the asteroid. Chief lunar exploration engineer Wu Wei-Ren says "We completed our mission very well today; this is our first time exploring asteroid". News anchor: "This is the world's first close-distance image capture of the Toutatis asteroid. It not only proves Ce-2's orbit design and navigation control but it also realizes China's improvement in its reach for space going from 400,000 km (moon) out to 7 million km from earth". Lunar exploration control project's assistant chief engineer Zhou Jian-Liang says "Sending a lunar exploration space ship that has fulfilled its mission to such an orbit is very challenging." "Our propulsion system was designed for long life; using x-band to send data back to earth from such a long distance is also difficult", says CE-2's assistant chief system engineer Wang xiao-Lei says. The completion of the extended mission by Ce-2 also means the satelite has successfully completed its overall mission. CE-2 was launched on October 1, 2010; After it successfully completed its six planned primary engineering and four scienctific missions at the moon; it flew to the L2 point about 1.5 million km from earth then to the Toutatis asteroid about 7 milliom km from earth. Exceeding at each station China's lunar and deep space exploration achievement.

Bob Ware: 12/16/2012 09:40 CST

IMPRESSIVE!!!!! Congratulations to China for a job excellently done!

Bob Ware: 12/16/2012 09:47 CST

Toutatis looks like it is comprised of either 2 major blocks and a 'dirt bridge at the contact point or 2 major blocks with a minor block caught in between. Any ideas on that?

JimOberg: 12/17/2012 10:41 CST

My space navigation and rendezvous experience is limited to about 400 km altitude, so i'd like to ask the REAL deep space navigators whether they think the 3 km miss distance reflects a guided aim point, or perhaps an accidental almost-crash for a more prudently distant aim point. Dang -- but aiming at a skim-surface point with a mission disaster error of +/- 3 km is really sharp shooting, if it was the original intent.

Starmon: 12/17/2012 01:26 CST

This is not 7 individual images of the asteroid. It is ONE image that has been reduced 6 times. They are using a 'webcam' for imaging!?! Any resolution of detail would be almost negligible in the smallest images. The sat. is moving 150-60 miles in approach and the asteroid is rotating, why is the exact same face on ALL of the iterations?

Jim Gordon: 12/17/2012 10:21 CST

Emily Lakdawalla, http://en.wikipedia.org/wiki/Shutter_speed If Chang'e launched in 2007 then 1/4000 s was extremely fast Realitive speed 10.73km/s is 2.68m of travel of astroid for a picture. A bullet travels at .860km/s or 860m/s that is 12 times slower. http://en.wikipedia.org/wiki/.308_Winchester http://en.wikipedia.org/wiki/Chang%27e_2 Does not give specs on camera, http://english.opt.cas.cn/rh/rps/200907/t20090714_23340.html has a picture of camera. and the picture was taken from a long way? Can someone with better knowledge on this type of technology point me in the right direction?

Starmon: 12/17/2012 11:16 CST

I queried my astro-list-serve (FRAC) and I was shown the errors of my ways. I had not considered the sequence period (15sec.). I had thought the sat. took images through a 180* track, as it approach, then receded from the asteroid. But it only did imaged on approach to the asteroid and then probably went out of the FOV (some 1.2*), when the sat got closer than 93 km. From my friend Ian K. "Tom, Per Wikipedia, the rotation period of Toutatis is 5.38 days. That sequence of images was taken over a period of 15 seconds. The total rotation in that time would be about 0.01 degrees, which would simply not be visible at that resolution. The closest image was taken at 93 km, the farthest at 240 km, and the approach was a mere 3.2 km. A bit of trig shows that the angle between the 93 km and 240 km images is about 1.2 degrees, or 1/150th of a half-rotation. The largest image in the link you supplied appears to be scaled up by a factor of four. Scaling it back down, the effective resolution of Toutatis is about 200 pixels length-wise by 77 pixels width-wise. If that's the closest image, then the resolution of the farthest image would be about 77 pixels by 30 pixels. Assuming that the flyby was at one of the long ends of the asteroid, that means that the apparent rotation would be approximately half a pixel. Near the center, it would be more like a fifth of a pixel. Again, that's too small to discern, at least without some good image analysis tools and a better source image. As for the comparison to the Stardust and Deep Impact missions, those missions both visited comets. Toutatis is not a comet; it has no coma and (as far as I know) does not shed a potentially hazardous quantity of dust. Cheers, Ian "..................SORRYyyyyy.........

Jeff Rabb: 12/26/2012 02:38 CST

Did the Chinese by chance provide and any density measurements with that flyby? At only 3.2 km at closest approach, they should have gotten some exceptionally accurate measurerments.

Jim O: 01/07/2013 11:27 CST

Three weeks and not another word about the fly-by in the Chinese news media. I find that very odd, and deserving of some pointed inquiries. Are we agreed -- only one single image was returned?

Emily Lakdawalla: 01/09/2013 02:29 CST

It's definitely more than one image, but I don't know if it's more than two. Hopefully we'll hear some answers at next week's OPAG meeting.

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