CE-2 flyby of Toutatis |
CE-2 flyby of Toutatis |
Aug 25 2012, 04:27 PM
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#1
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
I thought it was time to split the subject from the Moon forum.
Admins, can you move the relevant messages here? anyway, just out: an interesting blog article by Bill Gray explaining how he recovered the probe and how he computed the orbit yielding the 13 December flyby date Chang'e 2: The Full Story |
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Aug 27 2012, 10:02 AM
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#2
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
a few more observations of Chang'e 2 (designated 2010-050A by the COSPAR) in solar orbit were made last saturday by the Catalina Sky Survey
http://www.minorplanetcenter.net/iau/DASO/...DASO_000449.txt I hope Bill Gray will soon be using them to update its orbit determination and encounter estimates |
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Sep 1 2012, 10:03 PM
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#3
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Member Group: Members Posts: 495 Joined: 12-February 12 Member No.: 6336 |
Interesting story thank you for sharing.
Mr Gray seem to be quite the detective and he do use the word 'sleuth' as well. =) |
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Sep 1 2012, 10:19 PM
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#4
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Member Group: Members Posts: 613 Joined: 23-February 07 From: Occasionally in Columbia, MD Member No.: 1764 |
I don't suppose they'll rename the spacecraft 'Obelix'....
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Oct 7 2012, 08:37 AM
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#5
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
I have got a copy of this paper presented at last week's IAF Congress
Low energy trajectory optimization for CE-2’s extended mission after 2012 I will not share the paper, but I can tell you something more about the Toutatis flyby - first of all: 13 December 2012 is confirmed as the date. no distance nor relative speed or other details are given - we are told that the Beijing Aerospace Control Center called for proposals on a mission beyond L2 in January 2012. - there were lots of interesting proposals including one that would flyby Earth and Moon repeatedly, visit the L1 and L2 Lagrangian points, flyby a hundred-meter sized asteroid and finally explore the L4 Sun-Earth point in 2017 (the paper states that CE-2 would have been the first mission to do so. I think one of the two Stereos was first) - in March 2012 the Toutatis flyby, proposed by the Chinese Academy of Space Technology was selected - in a non-optimized form, the mission would have cost 107.5 m/s of the remaining 120 m/s delta-v budget - a 6.2 m/s correction on 15 April "was mainly used to keep the Lissajous trajectory". it was previously reported as the date CE-2 was maneuvered out of the L2 halo orbit - trajectory optimization was only carried out starting on 16 April. After optimization, an additional 22 m/s delta-v was gained that could be used to ensure a successful flyby - the first targeting maneuver was carried out on 31 May (32.9 m/s) - the second targeting maneuver (46.5 m/s) was to be carried out on 24 September |
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Oct 10 2012, 01:45 PM
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#6
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Member Group: Members Posts: 149 Joined: 18-June 08 Member No.: 4216 |
According to JPL's HORIZONS ephemeris service,
(Some of) The vital statistics of Toutatis on the 13th December 2012 are as follows: Epoch (UT) () Geocentric distance () Apparent Magnitude () Solar Elongation () (AU) () () (deg) 13/12 00:00 () 0.0466 () 10.73 () 125 13/12 12:00 () 0.0471 () 10.65 () 128 14/12 00:00 () 0.0478 () 10.59 () 132 Toutatis will be east of the sun and so an evening object in the sky. Judging from the magnitude and solar elongation, I would say that it is well within reach of backyard observers (including myself). Regards to All, Tolis. |
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Oct 10 2012, 03:15 PM
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#7
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
I saw it in November 1996 using a small, 114 mm telescope. under dark skies, it was easy to spot and it was amazing to see it clearly glide against the background stars
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Oct 11 2012, 07:00 AM
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#8
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
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Oct 12 2012, 10:22 AM
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#9
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Member Group: Members Posts: 149 Joined: 18-June 08 Member No.: 4216 |
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Oct 28 2012, 08:43 AM
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#10
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
to answer Phil Stooke's question in another thread http://www.unmannedspaceflight.com/index.p...st&p=193809 about the CE-2 end of mission I noted playing with the orbital elements published by Bill Gray that the orbital period of the probe is now 1.044 years that is it will trail behind the Earth by 15 degrees every year. in four years that is in July 2016 it will pass close to the trailing Lagrangian point L5. It will then be back in the vicinity of Earth in 24 years.
I pointed this out to someone in China who worked on orbit design for the Toutatis flyby but he told me that this is a pure coincidence and that it was not done on purpose BTW I posted this graph of the orbit of CE-2 up to the end of 2016 in a fixed Sun-Earth reference to the NASAspaceflight forum a few weeks ago. L5 is the red dot. |
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Oct 28 2012, 01:38 PM
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#11
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Solar System Cartographer Group: Members Posts: 10229 Joined: 5-April 05 From: Canada Member No.: 227 |
Excellent - thanks for this.
Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PDF: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Oct 28 2012, 03:49 PM
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#12
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Member Group: Members Posts: 447 Joined: 1-July 05 From: New York City Member No.: 424 |
The link to Bill Gray's August 25 planetary.org article in post # 1 is broken.
I found the post at: http://www.planetary.org/blogs/guest-blogs...full-story.html |
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Dec 5 2012, 06:29 PM
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#13
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
just tweeted by @asrivkin at the AGU meeting
QUOTE In asteroid news, China's Chang'E 2 will fly by the asteroid Toutatis in a few weeks. My (USA) source tells me it'll get 2 images which to me confirms the difficulty of imaging Toutatis with a push-broom camera instead of a proper 2-dimensional CCD |
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Dec 5 2012, 07:10 PM
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#14
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Solar System Cartographer Group: Members Posts: 10229 Joined: 5-April 05 From: Canada Member No.: 227 |
Check out this e-poster from the current AGU meeting:
http://fallmeeting.agu.org/2012/eposters/eposter/p31a-1873/ This is about radar imaging of Toutatis. Even if we only get a couple of reasonably well resolved images of Toutatis, it will be a big help in interpreting the radar images which contain complex ambiguities. There is a detailed shape model, but such models are also not without problems. Plus of course, there will be some information (we would hope) about albedo variations etc. which the radar does not give. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PDF: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Dec 5 2012, 07:20 PM
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#15
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
I saw it. It's a pity that 2 pics will not be enough to reveal the complex spin of Toutatis
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