Emily LakdawallaJan 09, 2013

The Chang'e 3 lunar lander and rover, expected to launch late this year

One of the missions planned for launch this year is China's Chang'E 3. I had never paid any attention to Chang'E 3 until this week, so I had no idea how large or ambitious it is. Chang'E 3 is a 1200-kilogram, RTG-powered lunar soft lander with a 1-year nominal mission lifetime. On top of that, it includes a 100-kilogram rover equipped with cameras and APXS. The rover has a nominal lifetime of 3 months and range of 10 kilometers. Wow. Here's a cool artist's concept that Glen Nagle put together. Enjoy it -- this is the first time it's been published!

I find that the best place on the Internet to find information and links about Asian missions is NASAspaceflight.com. Following is a summary of information from links posted within the NASAspaceflight Chang'E 3 forum. Many thanks to all the participants in that forum for sharing all this helpful information! I've collected all the photos of Chang'E 3 that I could find there and put them into a single Flickr album:

China announced late in 2011 that Chang'E 3 would be a lunar soft lander, to launch in 2013. Computer animations played on Chinese TV around that time (go to the 30-second mark) showed a lander deploying a smaller MER-like, solar-powered rover, with six basket-rimmed wheels and two pairs of cameras on a mast. It is expected to land in Sinus Iridum, an area well surveyed by Chang'E 2.

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This website describes the mission in some detail, but it doesn't state who it was written by, or what its sources are, so consider this paragraph unconfirmed data. The launch mass of Chang'E 3 is 3700-3800kg. After arriving in a 100-kilometer circular orbit, a 1200-kg Lunar Landing Vehicle will separate and transfer to a 100-by-15 kilometer orbit. It will descend under power of thrusters to an altitude of 100 meters, at which point it will hover and use autonomous hazard avoidance capability to move horizontally until it has found a smooth place to land. Then it will descend to 4 meters, cut the engines, and drop to the surface. Once on the Moon, it has an operational lifetime of 12 lunar days.

According to this news article from August 2012, Chang'E 3 will be powered by a plutonium-238 radioisotope thermoelectric generator (RTG) in addition to the solar panels visible on the models. I had not been aware that China could produce the plutonium isotope needed to power an RTG. The article gives the impression that the RTG is there primarily to keep the spacecraft alive during lunar night.

The mission of the lander/rover is to perform "territory surveys, living conditions assessment, and space observations," according to a Xinhua article quoting Ye Peijian, chief commander of Chang'E 3 at China Academy of Space Technology.

The rover will weigh 100 kilograms and is intended to last 3 months, which means it can survive at least 3 long, cold lunar nights. If I'm interpreting the article correctly, it will be equipped with some autonomous hazard avoidance and navigation capability but will also be directly controllable from Earth.

The English-language website I linked to before says that the rover has an expected range of 10 kilometers and carries a 20-kilogram science payload.

Ouyang Ziyuan made this a lengthy presentation to the China Academy of Science about China's plans in space, I think in June 2012. It's the same presentation in which the plans to explore Toutatis with Chang'E 2 were disclosed. At the 208-minute mark, he spends about 10 minutes on Chang'E 3. User "Galactic Penguin" at NASAspaceflight.com translated and posted a few key details about the spacecraft from this post about Ouyang's presentation on a Chinese spaceflight forum:

1. The lander will carry an optical telescope (probably not that big, around a dozen cm in diameter) that would conduct the first ever astronomical observation from the lunar surface (well, the later Apollo J-class CSM came rather close....). This telescope will operate in the near UV region, and will target close binary stars, active galactic nuclei, short-period variable stars etc.

2. Also on the lander is a far UV region camera that will observe the 30.4 nanometer band radiation from the Earth's ionosphere, another first in lunar exploration. This will monitor the effect of space weather, solar activity, Earth's geomagnetic field and particle streams on the Earth's ionosphere.

3. The rover will carry a radar on it's bottom side, allowing for the first direct observation of the structure and depth of lunar soil down to 30 meters deep and the lunar crust structure down to a depth several hundred meters.

Other instruments include:

Lander: 3 x panoramic cameras, 1 x descent camera, 1 x extensible lunar soil probe, 1 x lander engineering package, 1 x lander data controller

Rover: 2 x panoramic cameras, 2 x navigation and engineering camera sets, 1 x alpha particle X-ray spectrometer, 1 x infrared spectrometer, 1 x lander engineering package, 1 x lander data controller.

The lander phase is rather conventional, but it includes a 100 second hovering phase for the lander to take photos of the landing area and find a flat spot for landing.

Assembly of Chang'E 3 began in March 2012. According to otherwise unconfirmed information on this site, that date represented a 10-month delay over the original plan.

Here is a very cool video from a December 15 news report showing assembly of the lander, testing of the rover, and some animations of the landing and roving:

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According to "Galactic Penguin," the report states that "The rover can tolerate moving on a 20 degree slope and crossing over 20cm high obstacles (note that the landing zone at Sinus Iridium only has slopes up to 7 degrees); and the lunar simulation lab uses volcanic ash as a lunar soil replacement." One of the other stories I linked to above talks about the problematic nature of volcanic ash in terms of the respiratory risks it poses to the human engineers.

Chang'E 3 is part of a three-phase lunar exploration program consisting of an orbital reconnaissance phase, now completed (Chang'E 1 and Chang'E 2), a soft-landing phase (Chang'E 3 and likely Chang'E 4) and a sample-return phase (likely Chang'E 5 and Chang'E 6). The Google translation of this three-phase plan in this post is "around, down, back", a turn of phrase that I like!  In each phase, two spacecraft are built simultaneously, but only one launched at a time.

With Chang'E 5, described in a China Daily article from March 16, 2012, they hope to return 2 kilograms of lunar material to Earth. This is considerably more mass than has been returned autonomously from any place in the solar system; the previous record holders are the Luna soft landers, which returned a total of 326 grams of material over three missions from the Moon between 1970 and 1976. To return this much mass, China is adopting a complex relay strategy. A single launch will carry "a four-module spacecraft" to the Moon. Two of these will land, one of them being a sample collector (it does not appear, from mission artwork, to be mobile) and one an ascent module. The Chang'E 5 sample collector will have landing cameras, panoramic cameras, a "mineral spectrum analyzer" (perhaps an optical spectrometer?), "lunar soil gas analyzers" (maybe that means a GCMS?), a "lunar soil structure detector" (maybe a soil probe?), "core drilling machines and a mechanical sampler."

Chang'E 5 will require a new launcher, the Long March 5 rocket. According to this article, the Long March 5 will have its maiden launch at the end of 2014.

The ascent module will carry the sample to lunar orbit, where it will rendezvous with the mother ship. The mother ship will transfer the sample capsule to a return module that will bring the sample back to Earth. This doesn't seem to me to be the easiest way to accomplish lunar sample return, so my personal (and uninformed) guess is that the four-step process is being developed not just for lunar sample return but for some other purpose. China has proposed an Apollo-like human mission to the Moon, or they could, it seems to me, use the same process for autonomous sample return from an asteroid or Mars.

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