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CE-2 flyby of Toutatis
Phil Stooke
post Dec 11 2012, 02:59 PM
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http://echo.jpl.nasa.gov/asteroids/Toutati...2_planning.html


New images appearing on this site now - one other difference between radar and CE2 images, worth remembering - the visible images will have MUCH better signal to noise - radar images are speckly and show very little detail near the terminator (except bits of it which are tilted towards the radar, like a crater rim) - in fact it's sometimes hard to see where the radar terminator is. So the new images really will be complementary in many ways.

Phil



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machi
post Dec 11 2012, 05:06 PM
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Very interesting images. Here is image pair from 9. December in more "visible" look:
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Phil Stooke
post Dec 11 2012, 06:04 PM
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15 years ago I made a map of Toutatis, using an experimental image interpretation method. It was never published because of a dispute about the validity of the concept I had devised. This is the map, in case anybody is interested. Apart from the concept I used to convert the geometry of radar images to the equivalent of visible images for mapping (that's where the dispute came in) I also tended to push my interpretation of craters too far in those days. Every little hollow became a crater in my map. Now I would be more cautious in my interpretation. (Note - rotation is about the long axis - and because of ambiguity in the images, this might be a mirror image of the real surface)

Phil

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Paolo
post Dec 13 2012, 01:07 PM
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anybody knows whether ESA is providing tracking support to CE-2?
otherwise, has anybody tried computing the windows of visibility for the Chinese Deep Space Network stations? just to know when we can expect to have some news of the flyby


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Greenish
post Dec 13 2012, 03:00 PM
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The images at http://echo.jpl.nasa.gov/asteroids/Toutati...2_planning.html get better every day. Will be really interesting to see how the delay-doppler representations compare to the visible light ones.

I just noticed the following on that page: "Scheduling update: due to an equipment failure, radar observations of Toutatis at Arecibo were cancelled." Not sure when this appeared... Can anyone explain what the potential impact could be on the observing campaign? Not that I'm complaining, the Goldstone quick results are great and impressive on their own.
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Phil Stooke
post Dec 14 2012, 03:57 PM
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I don't see anything in the online chinese press yet.

Phil



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Paolo
post Dec 14 2012, 04:14 PM
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I have seen a release (in Chinese) on the site of the Chinese Academy of Sciences.
I don't have a link at hand, but it really didn't say anything new.


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machi
post Dec 14 2012, 04:43 PM
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I read on multiple Chinese pages, that they planned ~12 images of Toutatis.
But source is unknown, respectively it's some astronomer in Beijing. smile.gif

EDIT:
Here is info from Chinese Academy of Sciences.


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Paolo
post Dec 14 2012, 05:46 PM
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be sure to check this!
http://www.youtube.com/watch?v=waH9zfEbNJs


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Phil Stooke
post Dec 14 2012, 06:51 PM
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The radar video is great - first time I have seen something like this, and it does a fantastic job of resolving the front-to-back ambiguity. In a still image you can often see two lobes appearing to intersect, but you can't tell which is in front and which behind.

Phil



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machi
post Dec 14 2012, 07:53 PM
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The video is great, but Toutatis looks somewhat distorted.
On every image all sides are doubled, so it looks like two overlaid images of Toutatis:


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Phil Stooke
post Dec 14 2012, 08:05 PM
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That's because of the bizarre geometry of radar images. Imagine looking out over a range of hills with peaks at varying distances. Now imagine they are semi-transparent so you can see hills behind other hills. At the radar limb in these images, that is what we are seeing. The geometry is totally different from visible images. But with many images the ambiguities can be resolved - which is what this is all about, and why the Chinese images will be really useful. We have never had both high resolution radar and (reasonable resolution) visible imaging for any object before.

Phil



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tedstryk
post Dec 14 2012, 09:04 PM
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Assuming it is better than the 2002 NY40 images, this could be significant.


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yaohua2000
post Dec 14 2012, 11:27 PM
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Video: http://news.cntv.cn/china/20121215/100850.shtml

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 attitude 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
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Cosmic Penguin
post Dec 14 2012, 11:30 PM
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Just in from the Chinese news TV reports an hour ago: the fly-by was a success! 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:





Chinese news report about the fly-by (may translate it later if I have time): http://news.cntv.cn/china/20121215/100850.shtml

P.S. My first post here! smile.gif (my interest in planetary exploration started in grade 1 after seeing photos from the twin Voyagers)


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