[meteorite-list] China Probe Arrives in Lunar Orbit for Moon Landing

[Ron Baalke]

http://www.spaceflightnow.com/china/change3/131206loi/ 

Chinese probe arrives in lunar orbit for moon landing
BY STEPHEN CLARK
SPACEFLIGHT NOW
December 6, 2013

Less than five days after leaving Earth atop a blazing Long March launcher, 
China's Chang'e 3 spacecraft reached lunar orbit Friday to prepare for 
an historic rocket-assisted touchdown in the moon's Bay of Rainbows later 
this month.

Outfitted with a six-wheeled robotic rover and smarts to avoid hazards 
in the landing zone, Chang'e 3 is China's boldest unmanned space mission 
to date, extending feats achieved by a pair of lunar orbiters launched 
in 2007 and 2010.

The four-legged lander fired its propulsion system for six minutes and 
braked into orbit around the moon at 0953 GMT (4:53 a.m. EST) Friday, 
according to China's state-run Xinhua news agency.

The craft lifted off Dec. 1 on a Long March 3B rocket, which put the probe 
on a direct four-and-a-half day trajectory from Earth to the moon.

The spacecraft is now flying 100 kilometers, or about 60 miles, above 
the moon, Xinhua reported.

After lowering its altitude later this week, Chang'e 3 will fire a variable-thrust 
main engine to make a soft landing in the Bay of Rainbows, a dark lava 
plain on the upper-left quadrant of the moon's near side.

The lander has terrain recognition sensors to feed information into the 
probe's guidance computer, ensuring the spacecraft does not come down 
on a steep slope or in a boulder field.

A few feet above the moon, the lander will autonomously cut off its engine 
and drop to the surface. Engineers fastened shock absorbers to the landing 
legs to cushion the impact.

China has not disclosed the time of the landing, but European Space Agency 
officials supporting the mission with communications and tracking antennas 
say the touchdown is scheduled for some time Dec. 14.

Named Yutu or "jade rabbit," the mission's rover will drive off the landing 
platform a few hours later, according to ESA officials.

The rover has a mass of 140 kilograms, or about 308 pounds, and carries 
radioisotope heater units to keep the spacecraft warm during the two week-long 
lunar nights. The heaters are likely powered by small quantities of plutonium-238, 
the isotope of plutonium preferred for space missions, according to respected 
space researcher Dwayne Day, who discussed the rover's heaters in a story 
published in the Space Review.

The Yutu rover carries advanced radars to study the structure of the lunar 
crust at shallow depths along its path, and it is outfitted with spectrometers 
to detect the elements making up the moon's soil and rocks, said Pei Zhaoyu, 
a spokesperson for the Chang'e 3 mission, in a report by Xinhua.

Four navigation and panoramic cameras are mounted on the rover to return 
high-resolution images from the moon.

The mission also has an optical telescope for astronomical observations 
from the lunar surface, according to Pei.

China's lunar program is focused on robotic missions for now, with plans 
for an unmanned mission to return rock samples to Earth by 2020. China's 
military-run human space program is focused on development of a space 
station in Earth orbit around the same timeframe, but scientists have 
studied a manned lunar mission in the next decade.

Chang'e 3 will be China's first mission to test the technologies required 
for future lunar surface exploration.