Author Topic: LIVE: Chang'e-2 (China's second lunar probe) - Long March 3C - October 1, 2010  (Read 192316 times)

Offline Dalhousie

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Chinese sources have always been quite silent on this one, especially after it left moon orbit. I'm waiting for technical papers to know more.
BTW it''s the western media silence that shocks me more. not a single word in any specialized magazine and journal like Science, Nature or Aviation Week. it looks like CE2 never existed...
finally, I hope we will know something more next week when a presentation is scheduled to be given at the Small Bodies Assessment Group http://www.lpi.usra.edu/sbag/meetings/jan2013/agenda.shtml

Don't think the BBC mentioned it either.  Certainly not local news services.  I have hopes for LPSC though.
« Last Edit: 01/08/2013 07:39 AM by Dalhousie »
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline JimO

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I had one magazine story that got swallowed up in holiday vacations but will appear shortly -- will link.

Offline Star One

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Chinese sources have always been quite silent on this one, especially after it left moon orbit. I'm waiting for technical papers to know more.
BTW it''s the western media silence that shocks me more. not a single word in any specialized magazine and journal like Science, Nature or Aviation Week. it looks like CE2 never existed...
finally, I hope we will know something more next week when a presentation is scheduled to be given at the Small Bodies Assessment Group http://www.lpi.usra.edu/sbag/meetings/jan2013/agenda.shtml

Don't think the BBC mentioned it either.  Certainly not local news services.  I have hopes for LPSC though.

I can't remember seeing any mention of it in any astronomy magazines either.

Offline plutogno

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Offline Star One

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Sky & Telescope had the story on their website: http://www.skyandtelescope.com/news/Toutatis-Revealed-by-Chinese-Spacecraft-183673171.html

Thanks for the link. Lets see if it turns up in print. :)

Offline plutogno

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there is a technical parameter of Chang'e 2 that I have not been able to find in the literature and which will eventually influence the maximum distance at which it can be tracked: what is the diameter of its high gain antenna? anybody knows?

Offline Dalhousie

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there is a technical parameter of Chang'e 2 that I have not been able to find in the literature and which will eventually influence the maximum distance at which it can be tracked: what is the diameter of its high gain antenna? anybody knows?

This paper says that Chang'e 1 had a 0.6 m S band high gain antenna.

http://www.vlbi.csdb.cn/home/VLBIart/ce1/Chang%E2%80%99E-1_precision_orbit_determination_and_lunar_gravity_field_solution.pdf

"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline plutogno

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thank you. I had seen that paper but I had not spotted the datum...
it's the same paper that gives the coordinates for the Kashgar deep space antenna that I gave in a separate thread http://forum.nasaspaceflight.com/index.php?topic=30696.0
but there is nothing at those coordinates...

Offline plutogno

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the Chang'e 2 team has been awarded  the State Special Award for Scientific and Technological Progress.
http://news.xinhuanet.com/english/china/2013-01/18/c_132112663.htm

Offline powerplay2009

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Chang'e-2 is on the way to a destination of 20 millions KM away. Which star is there? It will arrive there in late March.

Chang'e -3 will be launched late this year. javascript:void(0);

latest source:
http://discovery.163.com/13/0119/08/8LIOA1GU000125LI.html

Offline Liss

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This message reflects my personal opinion based on open sources of information.

Offline plutogno

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Sky & Telescope had the story on their website: http://www.skyandtelescope.com/news/Toutatis-Revealed-by-Chinese-Spacecraft-183673171.html

Thanks for the link. Lets see if it turns up in print. :)

nothing in the March issue...

Offline JimO

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Offline Liss

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Here's my SPECTRUM story:

http://spectrum.ieee.org/aerospace/space-flight/details-emerge-of-change2-asteroid-encounter

Jim,
First of all I believe 15 km planned / 3.2 km actual figure is true.
Second, you may easily reconstruct the cold mathematical logic leading to such a bold flyby.
You have a spacecraft and a target with large uncertainties in orbit determination. As far as I understood, 11 km for CE2 and 5 km for Toutatis. And you have 10.73 km/s relative velocity.
You will never catch the target unless you do an easy thing: stay and watch in the direction of Toutatis departure after the closest approach. With a 7.2° FOW you will see asteroid from 240 km if standing 15 km from its path.
The Chinese were wildly lucky to find themselves only 3.2 km from the path of Toutatis -- with some 50 km minimal distance of viewing WRT its center and even closer for the off-center parts. But if not lucky, they'd still see it from 240 or 400 km or what.
« Last Edit: 01/31/2013 09:19 PM by Liss »
This message reflects my personal opinion based on open sources of information.

Offline plutogno

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actually, as near-Earth asteroids go, Toutatis has the smallest orbit uncertainties. other objects typically have uncertainties 100s or 1000s times larger.
also remarkable is that the Chinese achieved such a close flyby without OpNav (optical navigation), which would be impractical with all of the cameras on board. I think this is the first minor body flyby doing without of some degree of OpNav

Offline Satori

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Offline plutogno

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another academic paper on the asteroid selection process for CE-2
http://ams.cstam.org.cn/EN/Y2013/V29/I1/123#
it will take some more months until we see papers describing the extended mission in detail

Offline plutogno

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interesting: if I correctly understand this abstract (the full paper is in Chinese), solar sailing attitude control was tested when CE-2 was stationed at L2
http://zgkj.cast.cn/EN/abstract/abstract10662.shtml

Quote
Momentum Management of Chang'e-2 Satellite on L2 Point
DAI  Ju-Feng1, XU  Hong-Bing2, CUI  Yan2, XUE  Rui1

Abstract
Since Chang'e-2 (CE-2) satellite entered the Lissajous orbit surrounding the Earth-Sun Lagrange point L2,the effect of jet uninstall was studied. A momentum management method by light pressure was given. The in orbit test shows that the Solar light pressure is strong enough to unload the momentum of CE-2 satellite, which is surrounding the L2 point. This method can substantially reduce the number of jet uninstall, and benefit the orbit maintenance of CE-2 satellite.

Offline plutogno

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can anybody translate the latest posts on 9ifly?
http://bbs.9ifly.cn/thread-9843-121-1.html
if I understand correctly the google translation, CE-2 is to be put soon into hibernation?

Offline Galactic Penguin SST

can anybody translate the latest posts on 9ifly?
http://bbs.9ifly.cn/thread-9843-121-1.html
if I understand correctly the google translation, CE-2 is to be put soon into hibernation?

Close, although I think the report states that the spacecraft will not be completely shut down during the time CE-2 is too far away for the Chinese DSN to command it - the Chinese are just trying to see if it can survive the long way around the Sun.
Chinese spaceflight is a cosmic riddle wrapped in a galactic mystery inside an orbital enigma... - (not) Winston Churchill