China to the Moon - Chang'e program, Chinese unmanned lunar mission Options

[SFJCody]

Is that rocker-bogie? Doesn't JPL have a patent on that?

[stevesliva]

Is that rocker-bogie? Doesn't JPL have a patent on that?

They do, although they probably won't sweat the noncommercial use of it.

[hendric]

Wouldn't matter unless JPL patented it in China.

edit:

Looking at these pictures, it makes Scooterlord's MER render that much more amazing. Is it real, or is it Scooterlord? ™

[kenny]

The Chinese rover wheels are reminiscent of the Lunokods of the 1970s.

[elakdawalla]

Lunar Rover Test in the Kumtag Desert, Gansu Province

Can you post the original URL where these images came from?

(Cool stuff.)

[yaohua2000]

Can you post the original URL where these images came from?

(Cool stuff.)

From 9ifly forums: http://www.9ifly.cn/thread-364-5-2.html

The first few pictures were originally posted as a travelogue by ticker@newsmth (a team member): http://www.newsmth.net/bbsbfind.php?q=1&am...cks&dt=1000

[Paolo]

according to the google translation of a post on a Chinese forum http://www.9ifly.cn/forum.php?mod=viewthre...e=104#pid203109

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!

[Paolo]

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...

[Phil Stooke]

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

[yaohua2000]

Here is the full video of the presentation by Ouyang Ziyuan:

http://www.cas.cn/zt/hyzt/16thysdh/zb/fdsp...4_3598219.shtml

[Paolo]

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

[tedstryk]

I sure hope this is true (and, if so, successful) http://translate.google.com/translate?hl=e...26prmd%3Dimvnsu

[elakdawalla]

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.

[Paolo]

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?

[Paolo]

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