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

[Phil Stooke]

True, but at the cost of additional lunar science.

You're right of course that the solar orbit option was mentioned, but so were the other two options. No word yet on which one will actually be used. There's also no word on whether or not the previously described impact probe on Chang-E 2 even exists.

Phil

[yaohua2000]

Chang'e 2 may depart lunar orbit on June 16 for L2.

Reference: http://news.xinmin.cn/rollnews/2011/05/17/10777705.html (in Chinese)

[Paolo]

a nice article on the IEEE site: How China Plans To Send Robots To the Moon

[Tesheiner]

Chang'e 2 may depart lunar orbit on June 16 for L2.

Reference: http://news.xinmin.cn/rollnews/2011/05/17/10777705.html (in Chinese)

Ok, so L2 is on the far side of the Moon. My [perhaps uninformed] question is how will they communicate with the spacecraft?

Article on Emily's blog: http://www.planetary.org/blog/article/00003037/

[Phil Stooke]

L2 is not a point - it's a broad region, and the spacecraft orbit loosely around it, almost never hidden by the Moon. Right now NASA's ARTEMIS mission has two spacecraft, one orbiting L1 and one orbiting L2, waiting to go into lunar orbit in a few months for particles and fields studies.

Phil

[Hungry4info]

From Emily's blog post

In any case no images at all have ever been released from Chang'e 2 so even their quality is unknown.

Several images are here.

[centsworth_II]

Several images are here.

I guess she meant to say no full resolution images have been released.

Emily says in that post with the Chang'E 2 images that "... none of the versions of the images that I have found to be available online are anything close to their full stated resolution."

So the quality of any lunar map based on the originals is still unknown.

[elakdawalla]

I guess she meant to say no full resolution images have been released.

Um, yeah, that's what I meant. Actually, to be honest, I had totally forgotten about the release of any images, which is kind of shameful because I blogged them when they came out!

[yaohua2000]

This is a guideline how you can apply for these datasets: http://www.clep.org.cn/index.asp?modelname...000&recno=6 (in Chinese)

Normal users can only download "processed data products" (level-3 datasets) by sign up at http://159.226.88.59:7779/CE1OutWeb/ . For those have cooperation with the program, they can apply for raw datasets (level 0,1,2).

[gwiz]

L2 is not a point - it's a broad region, and the spacecraft orbit loosely around it, almost never hidden by the Moon. Right now NASA's ARTEMIS mission has two spacecraft, one orbiting L1 and one orbiting L2, waiting to go into lunar orbit in a few months for particles and fields studies.

Phil

According to the current Aviation Week, it's going to the Sun-Earth L2 point, not the Earth-Moon one. As far as I understand the machine-translated original Chinese announcement, this is correct.

[Phil Stooke]

Thanks - that's useful. Same point is true about it bing a large zone rather than a point - in fact it's much larger! What will it do after that, I wonder? Return to Earth orbit or Lunar orbit? Or go further out?

Phil

[remcook]

In theory, L2 is in fact a point. However, spacecraft never actually 'sit'in this point, but move in large orbits ( http://en.wikipedia.org/wiki/Halo_orbit ) around it. The point itself is dynamically unstable anyway (as opposed to the L4 and L5 points), so it would take effort to maintain your position there. In theory, halo orbits are stable, but in practise they get perturbed.

[centsworth_II]

L2 could be compared to a body, like the Earth, around which objects can orbit. Although the the center of Earth's gravitational field is a point, many objects can orbit it. In the same way, although the center of L2's influence is a point, many objects can orbit it. (That's how I see it anyway.)

[nprev]

I'm kind of wondering why they're going there. Navigation practice is my best guess. Wonder if they ever considered trying for an NEO flyby (assuming that there are any that Chang'e 2 could reach)?

[remcook]

My guess is that it's just hitting the highway http://www.cds.caltech.edu/~shane/superhig...escription.html

Also check out the Genesis mission for this. http://www.whydomath.org/node/space/second...ci_genesis.html