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Full Version: China to the Moon - Chang'e 1 and 2
Unmanned Spaceflight.com > Earth & Moon > Lunar Exploration > Chang'e program
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Phil Stooke
My impression is that it will be similar in lighting and resolution to Clementine. 100 m/pixel, fairly high sun at low latitudes. But that's not to say it will be identical. It is multispectral, and may sample different spectral bands than Clementine. Clementine has some poor areas where missed strips were filled in from higher altitude images, this might not. Also near the poles the lighting will be a bit different depending on the lunar seasons - Clementine only mapped for a couple of months so it saw limited seasonal variation. (for instance, the south rim of Shoemaker is visible here but not in Clementine). If we do get the full data set released, as China says we will - it will be complementary to Clementine.

Phil
Zvezdichko
Lunar South Pole as imaged by Chang'e and Clementine.
Phil Stooke
Reports now that Chang-e 1 has lowered its orbit to 100 km for a period of higher resolution imaging, to be followed by another drop in altitude to test systems for future landers - presumably navigation towards a final impact. So next year we'll probably see five lunar impacts - Kaguya's relay satellite, Kaguya itself, LCROSS's rocket stage and observation satellite, and Chang-e 1. Not necessarily in that order.

Phil
Phil Stooke
... and you might like to see what this update says about future missions, and data access:

http://www.lpi.usra.edu/features/chang_e/mapComplete/

Phil
Zvezdichko
http://yolearnchinese.com/archives/chinese...ed#comment-8074

Do you notice something weird?

EDIT: Everything is OK now. A credit line is given and a hyperlink to unmannedspaceflight.com was added.
Zvezdichko
http://news.xinhuanet.com/english/2009-01/...nt_10625458.htm

According to this publication Chang'e will impact the Moon in proper time, but not detail is given, as usual mad.gif
Geert
Chang'e has impacted the moon after de-orbit burn

see http://www.chinadaily.com.cn/china/2009-03...ent_7523687.htm

Regards,

Geert
Phil Stooke
Another point on the map! This is in Mare Fecunditatis, about 120 km west of the Luna 16 landing site.

Phil
nprev
Anybody know why Chang'e was deliberately deorbited @ EOM? I'm just wondering why they'd bother; it wasn't targeted towards a suspected volatile-rich area or anything like that.
Phil Stooke
Lunar spacecraft may be removed from orbit so they won't interfere with other missions - a second Chinese orbiter will follow this one and they may need to avoid communications issues - and also, they may be brought down in a controlled manner, if it's possible, to avoid damaging historic sites.

Phil
nprev
Thanks, Phil. I sort of thought that was why, but lunar orbit is hardly crowded these days. Concur with the historical site aviodance rationale, of course.
dvandorn
Although, I have to wonder -- what are the odds against an unguided impact by Chang'e (or anything else, for that matter) hitting an area of historical importance?

How many of these locations are there? Six Apollo sites, five Surveyor sites, two Lunakhod sites, three Luna sample return sites and two simple Luna lander sites -- a total of 18 sites, over the entire surface area of the Moon. (This assumes you're not going to count impact sites -- many of them unidentified -- of other hardware, from Luna 2 through Chandrayaan's MIP. I find it hard to imagine a tourist viewing platform to observe what appears to be just another crater out of quadrillions, just because it was made by a man-made vehicle. Though I might make an exception for Luna 2.)

I understand that a vehicle in polar orbit does eventually overfly most all of the Moon. But that also means it has the entire surface area of the whole body on which to impact, raising the odds significantly against an unguided impact coming within a hundred km of *any* given spot.

The idea of historic site preservation is a good one, but I just have to wonder what the odds of an inadvertent impact really are... huh.gif

-the other Doug
centsworth_II
QUOTE (dvandorn @ Mar 2 2009, 12:13 AM) *
Although, I have to wonder -- what are the odds...

We recently experienced an "improbable" mid orbit collision here at Earth. And the volume of possible lunar orbits is a lot smaller.

Someone at the BAUT forum indicated that Chinese media reported the de-orbit was used as training for future landing missions.
(Link to post below)

http://www.bautforum.com/space-exploration...tml#post1446047

EDIT: link to the Chinese news report from The Planetary Society Blog:
"The planned impact was designed to accumulate experience for landing of China's second lunar probe."
<a href="http://www.chinadaily.com.cn/china/2009-03...ent_7523687.htm" target="_blank">http://www.chinadaily.com.cn/china/2009-03...ent_7523687.htm
</a>
Zvezdichko
Some people report that the landing was recored by the CCD camera. Do you have any idea whether any pictures will be published, or as usual, nothing will appear?
Zvezdichko
I'm asking and I'm answering myself:

http://www.youtube.com/watch?v=Pw15rDMeYko

Take a look of the 29 and 30s second of the clip. Are these images of the impact?
Phil Stooke
They may have been taken during the descent, or may be oblique views from another orbit.


Replying to dvandorn's point above - of course the chance of an unintended strike on a historic site is minimal. Communication interference, or learning to track a descent trajectory, are more likely. But there is an agreement to deorbit in a controlled way if possible rather than leaving things to chance.

Phil
Phil Stooke
Here's an updated map of the lunar near side with the recent impacts on it. I included Chandrayaan 1 but I don't know its true location - Goswami says 88 south, but does not specify a longitude. It came in along roughly the 15 east meridian, but it might have made it to the far side if it overflew the pole.

Phil

Click to view attachment
Geert
QUOTE (Phil Stooke @ Mar 2 2009, 06:52 PM) *
Communication interference, or learning to track a descent trajectory, are more likely.


Remembering all the problems that mascons gave on earlier lunar landings, tracking a descent trajectory might indeed be worthwhile.

Which immediately leads to another question: given that mascons are very local interferences, it stands to reason that you would like to track the same trajectory that you're lander is supposed to follow, otherwise tracking a descent wouldn't teach you much. So possibly the Chinese lander will land somewhere in the same region as this crash??

And one more item, this position is not far from the Luna 16 position, and those sample-return landingpoints were chosen as only from this longitude you can fly a direct ascent trajectory back to earth without having to do midcourse burns. I don't suppose the Chinese will try a sample-return on their very first landing, but IF they are intending to land somewhere in this vicinity it is at least remarkable that they select a location which allows a direct ascent trajectory..

Regards,

Geert.
Zvezdichko



Photo Credit : CCTV/CNSA




Photo Credit : CCTV/CNSA

These are the candidate images that were probably taken during impact.
djellison
It's not going to be DURING impact. Just before it, perhaps, but not during.
Phil Stooke
A stretched out version - easier to try to locate it. But I don't recognize the area. This has north up, from the lighting direction, if it's taken on the last orbit.

Phil

Click to view attachment
Paolo
This Aviation Week article http://www.aviationweek.com/aw/generic/sto...china092809.xml is mostly about MSF, but it does say that Chang'e 2 will fly in October 2010.
"Improvements include a better camera with a resolution of 5 meters (16.4 ft.) at the surface, they say."
Zvezdichko
http://www.novosti-kosmonavtiki.ru/content/news.shtml

Novosti-Kosmonavtiki confirms launch in October 2010 and it is also said that Chang'e 2 will be 100 kms closer to the lunar surface. It's also said that the instruments will be even more sophisticated and powerful, but I don't know about the resolution of the camera.

Chang'e 2 will be based on a back-up spacecraft for Chang'e 1 already built. Initially it was supposed to be launched as-is, as a clone of Chang'e 1, but now it's confirmed it will carry more powerful instruments.

Novosti-Kosmonavtiki also says the moon rover will be launched no later than 2013. The moon rover will study the local resources, particularly minerals. The rover will be a stepping stone to a human mission to the Moon, which has to occur no later than 2030.
Zvezdichko
http://www.spacedaily.com/reports/Change_1...ration_999.html

A new article plus a thumbnail of the topographic map. Do you have any idea if we already have a bigger version somewhere?

http://www.physorg.com/newman/gfx/news/hir...hange1hasbl.jpg
nprev
100 km closer using the same spacecraft bus & upgraded instruments, eh? They don't seem too worried about thermal problems.
Hungry4info
Perhaps with the information gained from their first lunar mission, they're confident they'll be able to handle it. On the other hand, if they suddenly consider raising altitude for a better view, we'll know what's happening laugh.gif
Phil Stooke
LRO's at 50 km and it's not bothering them.

Phil
nprev
Surely. I was being kind of elliptical; it appears that they are quite confident in their basic design is what I meant.
IM4
QUOTE (Zvezdichko @ Dec 2 2009, 01:39 PM) *
Do you have any idea if we already have a bigger version somewhere?

Yes, we have. See attachments below. First one is topographical map from Chang'e Laser Altimeter with North/South pole views presented. Second one is a kind of microwave map at 37 GHz. I can't translate the title, but I suppose it presents a microwave emissivity of the moon regolith.

Hendrik
微波月亮 34Ghz 白天正面/背面

microwave moon 34Ghz Daytime Frontside/Backside
Phil Stooke
(checking in from vacation)

(like, who can stay away from UMSF even if a vacation is supposed to be happening?)

So now I hear that Chang-e 2, the Moon orbiter due to launch in October this year, will be carrying a small lunar impact probe, as Chandrayaan 1 did. Presumably it will be testing tracking, altimetry etc., and maybe imaging down to the surface in support of the lander scheduled for 2013.

Phil
rlorenz
QUOTE (IM4 @ Dec 5 2009, 06:47 AM) *
I can't translate the title, but I suppose it presents a microwave emissivity of the moon regolith.


Microwave brightness temperature (there is a color scalebar in K on the plot..)
This has an emissivity contribution, but is dominated by the physical temperature
which in this case is dominated by latitude.

There have been a few papers published on these (nice) data - possibly some of the
most solid results from Chang'e so far, or at least results complementary to what
everyone else has flown.

e.g. LPSC abstract http://www.lpi.usra.edu/meetings/lpsc2010/pdf/1331.pdf
Paolo
Lunar microwave temperature maps presented at EPSC
http://lunarscience.arc.nasa.gov/articles/...e-complete-moon
yaohua2000
Chang'e 2 will be launched at 10:59:57 UTC, tomorrow.

Wikipedia: http://en.wikipedia.org/wiki/Chang'e_2

Pictures: http://slide.news.sina.com.cn/c/slide_1_15699_13288.html
Astro0
Live launch coverage (in english) from CCTV seems to show a successful launch for Chang'e 2. Launch and booster sep all on time.
Click to view attachment
climber
More infos from Spaceflightnow.com: http://www.spaceflightnow.com/news/n1010/01change2launch/
climber
Watching launch on Emily's bog: http://www.planetary.org/blog/article/00002693/ , I can't believe the guy realy press the button to make the lift off happen! I'd say that's for show up purposes instead. What do you think?
OWW
Listening to that tv-host is hilarious. So clueless... rolleyes.gif
Paolo
There is an interesting sentence in the Spaceflight Now page:

QUOTE
Officials are considering three scenarios for Chang'e 2's overtime, including sending the spacecraft away from the moon and into deep space, giving Chinese engineers practice in operations further from Earth.


This remembers me of Clementine, the lunar orbiter that was to encounter two asteroids in deep space...
yaohua2000
TCM-2 and TCM-3 canceled. LOI is expected in 1.5 hours.
nprev
Good shooting! smile.gif Thanks for the update, Yaohua.
Hungry4info
Interesting. I sure hope that works out.
I'm quite eager to see new images from the lunar surface.
yaohua2000
The 490-Newton thrust main engine started at 03:05:59 UTC, burned for 1942 seconds. Chang'e 2 is now in lunar orbit at an altitude of 100 km.
nprev
Congratulations to CSNA & the people of China! smile.gif
charborob
QUOTE (yaohua2000 @ Oct 5 2010, 11:17 PM) *
The 490-Newton thrust main engine started at 03:05:59 UTC, burned for 1942 seconds. Chang'e 2 is now in lunar orbit at an altitude of 100 km.

To be precise, Chang'2 entered a preliminary 12-hour orbit. Two more adjustments are needed before it reaches the 100-km working orbit.
http://news.xinhuanet.com/english2010/chin.../c_13544216.htm
Phil Stooke
Chang-e 2 has been operating in its 100 km circular orbit for a while, probably testing its instruments and maybe collecting some data. Yesterday it began testing the camera system, and tomorrow it will drop into its 100 by 15 km low pass over Sinus Iridum for the first time.

This from a report in the People's Daily today.

Phil
elakdawalla
Link please Phil?
Phil Stooke
Sorry!

http://english.people.com.cn/90001/90776/90881/7176368.html
Phil
Phil Stooke
http://english.people.com.cn/90001/90776/90881/7178577.html

The spacecraft is in its 100 by 15 km orbit and will image Sinus Iridum tomorrow (Wednesday)

Phil
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