Article Posted on : - Oct 01, 2010

China had successfully launched its first lunar probe Chang'e-1 on October 24, 2007. A file photo

BEIJING (BNS): Countdown began on Friday to launch China’s second lunar mission, Chang'e-2, even as the country set the launch time at 6:59 pm from the Xichang Satellite Launch Centre in Sichuan Province.

The launch window will remain open till Sunday if the spacecraft misses Friday’s slot as weather conditions on Thursday remained a concern.

Drizzle or light rain would not interrupt the launch, but thunderstorms could, a spokesperson from the country’s national space agency CNSA was quoted as saying by the China Daily newspaper.

The lunar probe, which will be launched by the Long March 3C carrier rocket, will test key technology related to the “soft-landing” of its successor Chang'e-3 lunar landing mission planned for 2013.

Chang'e-2 will face “unknown risks” and three major challenges, according to the Chinese space authorities.

The first challenge for the spacecraft would be to enter directly into the Earth-Moon transfer orbit instead of orbiting the Earth first. The Chang'e-1 used a different procedure, orbiting the Earth first on its mission, Wu Weiren, chief designer of China’s lunar exploration programme, said.

The second challenge would be whether the probe can survive Moon's gravitational pull.

“If the braking is not well handled, the probe could either crash into the Moon, or fly away (from the preset orbit),” Wu said.

The third risk involves when the probe is maneouvered to an orbit just 15 km from the Moon during which it will take high-resolution images of the Moon’s ‘Bay of Rainbows’ area where the Chang'e-3 will land.

The maneouver to lower the orbit has to be done when the probe is on the dark side of the Moon, so that when it flies to the bright side it can take the photos. As the tracking and control system is unable to reach the dark side, the success of the operation relies on the satellite's technology, Wu was quoted as saying by the newspaper.

If successfully launched, the Chang'e-2 will take five days to reach its pre-set orbit, almost eight days faster than its predecessor, the Chang'e-1, and 100 km closer to the Moon.