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China to the Moon - Chang'e 1 and 2, Chinese unmanned lunar orbiters
Paolo
post Sep 21 2011, 07:32 PM
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the release is accompanied by a nice graph (in Chinese)



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Paolo
post Nov 7 2011, 08:24 PM
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what next for CE-2?
according to this interview (in Chinese) http://news.xinhuanet.com/politics/2011-09...c_122063243.htm it will remain at L2 until the end of next year. Then, depending on the remaining fuel it may fly to the Sun-Earth L1 point, flyby a near Earth asteroid or comet, or return to the Moon


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Paolo
post Feb 6 2012, 06:07 PM
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anybody seen this site before?
http://159.226.88.59:7779/CE1OutENGWeb/ce2files.jsp
"thumbnails" are actually full resolution images. under Mozilla: click right and then select "view image"


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Phil Stooke
post Feb 6 2012, 10:23 PM
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I had looked at that and some similar pages, but it never occurred to me to try and save the little thumbnail (since it didn't obviously link to anything). Now I'm happy!

Phil



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yaohua2000
post Feb 7 2012, 11:18 PM
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Recently released lunar global map, in JP2 format (1.4 GB compressed): ftp://DataRelease:1q2w124@159.226.88.39/C...obal-50m-sc.rar

You can also find some other Chang'e 2 stuffs on this FTP server.

An online viewer: http://159.226.88.30:8080/CE2release/cesMain.jsp

Attached Image


Left: Google Moon; Right: Chang'e 2
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Phil Stooke
post Feb 8 2012, 04:03 PM
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The new map is very nice. I have just put a comment on LPOD about this but I'll repeat it here. The zoomable map works like the LROC Quickmap, except it does not have the extra level of detail provided by the LROC NAC frames. But when I zoom in on areas I know very well, I can see that the new Chinese map is better than the LROC WAC mosaic. The sun angle is higher, so topography is not so clearly seen, but the resolution is better than LROC WAC.

Phil



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Paolo
post Jun 14 2012, 06:48 AM
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according to the google translation of a post on a Chinese forum http://www.9ifly.cn/forum.php?mod=viewthre...e=104#pid203109

QUOTE
The CE-2 in April, has left the L2 to probe asteroid is expected to close rendezvous with an asteroid in January next year.


the same forum points at main belt (3179) Beruti as the target. sounds strange, I would rather have expected a NEO!

I am hoping they got confused with (4179) Toutatis! I have been waiting to see Toutatis ever since the first radar images were released 20 years ago!


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I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.

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Paolo
post Jun 14 2012, 09:47 AM
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it now seems that Toutatis is indeed the target! the flyby will occur just weeks after the NEO has made a close approach within 0.046 AU of Earth.
I was wondering whether the Chinese have developed a moving target tracking algorithm to collect any data from the flyby or they will have to image all of the uncertainty volume of the asteroid in order to be sure of capturing it as Galileo did. any idea?
of course such software is not needed for a lunar orbiter...


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I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.

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Phil Stooke
post Jun 14 2012, 12:48 PM
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Very interesting. There is a mirror-image ambiguity in the radar image reconstructions, and it will be very interesting to see it resolved in optical images. I think the ambiguity continues into the shape models as well, certainly in the earlier versions.

Phil



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yaohua2000
post Jun 14 2012, 04:00 PM
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Here is the full video of the presentation by Ouyang Ziyuan:

http://www.cas.cn/zt/hyzt/16thysdh/zb/fdsp...4_3598219.shtml
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Paolo
post Jun 15 2012, 05:24 AM
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more info from NASAspaceflight forum, where I first saw the new, to give them proper credit (I am user plutogno) http://forum.nasaspaceflight.com/index.php?topic=19644.225
CE2 left the Lagrangian point on 15 April and will flyby Toutatis on 6 January next year


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I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.

James Van Allen
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tedstryk
post Jun 15 2012, 04:08 PM
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I sure hope this is true (and, if so, successful) http://translate.google.com/translate?hl=e...26prmd%3Dimvnsu


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elakdawalla
post Jun 15 2012, 09:20 PM
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According to a commenter on my blog who says he speaks Chinese and listened to the presentation, the future encounters (Tukmit, Apophis, etc) are for future missions, not Chang'E 2.


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Paolo
post Jun 15 2012, 09:46 PM
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to answer my question about autonomous tracking, I asked JPL's Horizons the 3-sigma error ellipse semiaxes in right ascension and declination for the day of the encounter for an observer located at the center of the Earth. It turns out Toutatis' orbit is extremely well known (thanks to radar observations, no doubt) and probably CE will simply need to point at the spot in the sky where the asteroid is supposed to be.
The orbital elements in fact have very small 1-sigma uncertainties (down to 1E-10 for the semimajor axis and eccentricity): http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=4179...cad=0#discovery
From Horizons, it turns out the 3-sigma error ellipse on encounter day is a mere 0.025 x 0.010 arcseconds wide. That is 1.21E-7 x 4.85E-8 radians. The distance from Earth at that time will be 0.1887 AU or 28.2 million kilometers.
From simple trigonometry, the error ellipse is just 28.2E6 sin (1.21E-7) = 3.4 km wide at maximum.
did I make any mistake? am I missing something?


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I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.

James Van Allen
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Paolo
post Jun 23 2012, 09:22 AM
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while waiting for details and news on the Toutatis mission (note that it's been more than a week since the story was leaked, and Chinese mainstream press has not yet picked it up), I have found an interesting if quite technical paper on Moon-to-L2 navigation
Pre-LOI trajectory maneuvers of the CHANG’E-2 libration point mission


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I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.

James Van Allen
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