A rocket carrying China's second unmanned lunar probe, Chang'e II, is at its final stage of preparation before launch, the Xichang Satellite Launch Center (XSLC) in southwestern Sichuan Province said Thursday.

Fueling of the Long March 3C rocket, the last procedure before its launch, began at 9 a.m. on Sept. 30.

Fu Jumei, of the XSLC, said the rocket's first and second stage boosters were fueled with conventional propellents Thursday. The fueling took about five hours.

The rocket's third stage booster will be fueled with cryogenic propellent, which is lighter and allows for more power.

The fueling of this part would not start until eight hours ahead of the launch, Fu said.

She said once the cryogenic propellent was added to the rocket, the launch would be irreversible.

The rocket will carry Chang'e II to a trans-lunar orbit, and then the satellite is expected to take about 112 hours, or nearly five days, to arrive at its lunar orbit.

The lunar probe will test key technologies and collect data for future landings of Chang'e III and Chang'e IV, and provide high-resolution photographs of the landing area.

Chang'e II was produced as an alternative to Chang'e I, which was launched in Oct. 2007. The series of Chang'e probes is named after a legendary Chinese moon goddess.