CE-2 flyby of Toutatis |
CE-2 flyby of Toutatis |
Nov 22 2013, 03:11 PM
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#151
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Senior Member Group: Admin Posts: 4763 Joined: 15-March 05 From: Glendale, AZ Member No.: 197 |
Be careful, you can't believe everything you read on the internet. -------------------- If Occam had heard my theory, things would be very different now.
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Nov 22 2013, 03:51 PM
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#152
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Administrator Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 |
one of the papers at this year's IAC had a closest distance of 1,564 +/- 10 m. from the center of mass, I think That's pretty amazing considering the long axis is 4.5 km. Be careful, you can't believe everything you read on the internet. -------------------- My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
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Nov 22 2013, 05:31 PM
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#153
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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 checked the paper "Relative Distance Estimation Between the Asteroid 4179 and Chang'E II Based On Spaceborne Opitcal Images" and it states:
QUOTE the distance of the relative motion curve from the centroid of Toutatis to Chang’e II, i.e., their actual fly-by distance, is calculated. so they are indeed not determining the distance from the surface. and later they conclude QUOTE the actual fly-by distance is 1564 m±~10 m. note also that the paper by Huang et al referenced by the Icarus paper is this one: http://tech.scichina.com:8082/sciE/CN/abst...act511202.shtml |
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Nov 22 2013, 05:33 PM
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#154
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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 |
by the way, Huang et al. (page 600) state, google translated:
QUOTE Flying over the nearest point from the target time: 770 ± 120 m;
Distance from the geometric center of the overflight time: 1.32 km ± 120 m; |
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Nov 22 2013, 06:36 PM
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#155
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Administrator Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 |
Thanks very much for digging those up! I will add those details into my blog post.
-------------------- My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
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Dec 12 2013, 05:47 PM
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#156
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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 |
another (open access, this time) paper on the scientific results of the flyby
The Ginger-shaped Asteroid 4179 Toutatis: New Observations from a Successful Flyby of Chang'e-2 |
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Dec 13 2013, 04:58 PM
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#157
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Newbie Group: Members Posts: 10 Joined: 27-August 12 Member No.: 6618 |
according to this paper
QUOTE Chang'e-2 implemented the flyby on 13 December 2012 at 8:29:58.7 UTC at a closest distance of 770 ± 120 (3σ) meters from Toutatis' surface at a high relative velocity of 10.73 km s−1, quite a close shave... -------------------- |
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Dec 13 2013, 05:04 PM
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#158
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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 |
quite a close shave... it still surprises me that they seem to have done it entirely without optical navigation. they just knew the exact orbit of the asteroid thanks to radar tracking and that of the probe thanks to ranging and they managed to pull out the closest flyby ever with these data |
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Dec 14 2013, 12:58 AM
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#159
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Senior Member Group: Admin Posts: 4763 Joined: 15-March 05 From: Glendale, AZ Member No.: 197 |
....they just knew the exact orbit of the asteroid thanks to radar tracking and that of the probe thanks to ranging and they managed to pull out the closest flyby ever .... There probably was some serendipity involved. -------------------- If Occam had heard my theory, things would be very different now.
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Dec 14 2013, 08:41 AM
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#160
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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 |
actually, they had a trajectory correction (and a sizeable one, 3.3 m/s) the day before the flyby, so I guess they were aiming for a very close encounter on purpose
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Apr 10 2014, 05:28 PM
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#161
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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 paper on the future orbit of CE-2, due for publication in the Chinese Science Bulletin: The Earth co-orbital motion and recapture of the Chang'e-2 spacecraft
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May 29 2014, 08:07 AM
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#162
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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 |
this interesting paper on the imaging strategy of CE-2 at Toutatis (which was also discussed on UMSF) has been published in Chinese Astronomy and Astrophysics: A Research on the Imaging Strategy and Imaging Simulation of Toutatis in the Chang’e-2 Flyby Mission.
the English version is unfortunately behind the paywall (but I have tried to contact the author to have a copy), while the Chinese version is available here. |
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Oct 25 2014, 06:34 AM
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#163
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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 |
this was just published online in Advances in Space Research (and, incredibly for Elsevier, seems to be in open access): Navigation of Chang’E-2 asteroid exploration mission and the minimum distance estimation during its fly-by of Toutatis
from a first, quick look, lots of interesting infos not published elsewhere: - a detailed timeline of the corrections maneuvers leading to the flyby - the targeted flyby distance was approx. 30 km but CE-2 ended being much closer (less than 2 km) to Toutatis - distant images of the Earth and Moon were taken after departure, on 31 July and 1 August 2012. apparently, these were taken to test the camera (the CMOS monitoring camera used during the flyby, I suspect). it would be nice to see these images... |
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