Author Topic: LIVE: Chang'e-2 (China's second lunar probe) - Long March 3C - October 1, 2010  (Read 187737 times)

Offline plutogno

  • Full Member
  • ****
  • Posts: 717
  • Toulouse, France and Milan, Italy
  • Liked: 113
  • Likes Given: 6
a paper presented at the IAC (still speaking of asteroid mission as an option):
http://images.spaceref.com/news/2012/chang'e-moon-iac2012.pdf

Offline plutogno

  • Full Member
  • ****
  • Posts: 717
  • Toulouse, France and Milan, Italy
  • Liked: 113
  • Likes Given: 6
this is behind the paywall, but you can still see the first two pages
First-round design of the flight scenario for Chang’e-2’s extended mission: takeoff from lunar orbit
http://rd.springer.com/article/10.1007/s10409-012-0111-x

Offline plutogno

  • Full Member
  • ****
  • Posts: 717
  • Toulouse, France and Milan, Italy
  • Liked: 113
  • Likes Given: 6
two papers to be presented at this year's IAC:

An Extended Mission of Chang’E-2 From Sun-Earth L2 point to Asteroid: Design and Analysis
http://www.iafastro.net/iac/paper/id/15114/summary.lite/

Low energy trajectory optimization for CE-2’s extended mission after 2012
http://www.iafastro.net/iac/paper/id/15724/summary.lite/

I have got a copy of the latter paper. I will not share it, 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

Offline Lsquirrel

  • Member
  • Posts: 83
  • Liked: 27
  • Likes Given: 3
two papers to be presented at this year's IAC:

An Extended Mission of Chang’E-2 From Sun-Earth L2 point to Asteroid: Design and Analysis
http://www.iafastro.net/iac/paper/id/15114/summary.lite/

Low energy trajectory optimization for CE-2’s extended mission after 2012
http://www.iafastro.net/iac/paper/id/15724/summary.lite/

I have got a copy of the latter paper. I will not share it, 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
Chang’E-2 will fly by 4179 Toutatis this year,and it will be explore L4?
« Last Edit: 10/08/2012 08:32 AM by Lsquirrel »

Offline plutogno

  • Full Member
  • ****
  • Posts: 717
  • Toulouse, France and Milan, Italy
  • Liked: 113
  • Likes Given: 6
Chang’E-2 will fly by 4179 Toutatis this year,and it will be explored L4?


that was a different mission extension. as I understand it, there will not be enough fuel remaining after the Toutatis flyby to do any other meaningful mission.

BTW from the orbital elements published by Bill Grey (semiaxis = 1.029 AU) one can compute an orbital period of 1.044 years, i.e. CE-2 will trail Earth by 15 degrees every year, meaning that it will be near the trailing Lagrangian point L5 anyway in four years
« Last Edit: 10/28/2012 07:51 AM by plutogno »

Offline plutogno

  • Full Member
  • ****
  • Posts: 717
  • Toulouse, France and Milan, Italy
  • Liked: 113
  • Likes Given: 6
a quick graph that I computed using the orbital elements given by Bill Gray.
it shows the motion of CE2 until the end of 2016 in a typical reference system that keeps the position of the Sun and Earth fixed. The Sun is at (0,0) and the Earth is the red dot at (1,0).
As you can see, CE2 will pass in the environs of the L5 point (red dot at lower right) in July 2016
« Last Edit: 10/28/2012 07:51 AM by plutogno »

Offline plutogno

  • Full Member
  • ****
  • Posts: 717
  • Toulouse, France and Milan, Italy
  • Liked: 113
  • Likes Given: 6
a new Chinese deep space station and radiotelescope is unveiled in Shanghai just in time to support CE-2
http://news.xinhuanet.com/english/sci/2012-10/28/c_131935824.htm

Offline plutogno

  • Full Member
  • ****
  • Posts: 717
  • Toulouse, France and Milan, Italy
  • Liked: 113
  • Likes Given: 6
a long article (in Chinese) on the development of CE2
http://zh.cnr.cn/2100zhfw/zhhz/201211/t20121114_511342196.shtml
and
http://zh.cnr.cn/2100zhfw/zhhz/201211/t20121114_511342196_1.shtml
it looks quite interesting. anybody willing to translate it?

Offline plutogno

  • Full Member
  • ****
  • Posts: 717
  • Toulouse, France and Milan, Italy
  • Liked: 113
  • Likes Given: 6
another interesting paper on CE2 mission design:

First-round design of the flight scenario for Chang’e-2’s extended mission: takeoff from lunar orbit
http://ams.cstam.org.cn/CN/article/downloadArticleFile.do?attachType=PDF&id=143726

Offline JimO

  • Veteran
  • Full Member
  • ****
  • Posts: 1813
  • Texas, USA
  • Liked: 215
  • Likes Given: 49

- the second targeting maneuver (46.5 m/s) was to be carried out on 24 September

any indication that burn succeeded?

we're close to encounter, and no further news.

it's too quiet.

emily update here:
http://www.planetary.org/blogs/emily-lakdawalla/2012/12061004-toutatis-preview.html
« Last Edit: 12/09/2012 02:41 AM by JimO »

Offline frank808

  • Member
  • Posts: 6
  • Liked: 2
  • Likes Given: 3
The fly-by was just confirmed by CCTV that it will take place today.

http://news.cntv.cn/china/20121213/100038.shtml

Online Satori

  • Moderator
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 12259
  • Braga - Portugal
    • Em Órbita
  • Liked: 347
  • Likes Given: 232
Chang'e-2 fly-by of Toutatis took place on December 13: http://scitech.people.com.cn/GB/n/2012/1214/c1007-19895649.html (in Chinese).

Not much info about it.

Offline 20350902

  • Member
  • Posts: 14
  • China
  • Liked: 0
  • Likes Given: 0
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
« Last Edit: 12/15/2012 06:55 AM by 20350902 »

Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2057
  • Liked: 251
  • Likes Given: 306
Image of Toutatis at 59 seconds in that video.  Well done to everyone at CNSA involved.
"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

Online Galactic Penguin SST

Another photo taken at 93 km away:
Chinese spaceflight is a cosmic riddle wrapped in a galactic mystery inside an orbital enigma... - (not) Winston Churchill

Offline frank808

  • Member
  • Posts: 6
  • Liked: 2
  • Likes Given: 3
Another photo taken at 93 km away:

What is the star on the right hand side?  The moon?

Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2057
  • Liked: 251
  • Likes Given: 306
AS predicted by some, looks like two merged rubble pile bodies.
"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 Dalhousie

  • Senior Member
  • *****
  • Posts: 2057
  • Liked: 251
  • Likes Given: 306
A few more details.

http://english.cri.cn/6909/2012/12/15/53s738568.htm

Given the very close flyby there should have been a range of data collected.  I imagine there should be some interesting talks at LPSC.
"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

  • Full Member
  • ****
  • Posts: 717
  • Toulouse, France and Milan, Italy
  • Liked: 113
  • Likes Given: 6
anybody know what the two sentences in purple between the L2 orbit and the Toutatis flyby mean?
http://ww1.sinaimg.cn/large/58b49184jw1dzubmjhtyhj.jpg

Online Liss

  • Full Member
  • ****
  • Posts: 905
  • Moscow, Russia
  • Liked: 108
  • Likes Given: 8
anybody know what the two sentences in purple between the L2 orbit and the Toutatis flyby mean?
http://ww1.sinaimg.cn/large/58b49184jw1dzubmjhtyhj.jpg
The first of the two has the same structure as the two previous purple phrases. I guess these denote 1st, 2nd and 3rd maneuvers. The last purple line may denote the approach TCM.
This message reflects my personal opinion based on open sources of information.