The Chang'e I lunar probe Monday successfully completed its third orbital transfer, taking it one step closer to completing its 1.58-million-km journey to the moon.

Officials from the Beijing Aerospace Control Center (BAAC) said the probe successfully transferred to a 48-hour orbit at about 6:01 pm. It will stay on that path until tomorrow, after which it is expected to enter an Earth-moon transfer orbit, a critical point that might determine whether or not the satellite reaches its final destination.

Now at a distance of more than 120,000 km from Earth, Chang'e I has set a new record in China's aerospace history as the most distant satellite ever controlled by Chinese scientists. The previous record stood at 80,000 km.

Wang Yejun, chief engineer with the BACC, said ultraviolet image sensors installed on the satellite will soon begin to collect information on the Earth and moon once it enters the 48-hour orbit.

The images will not be transmitted back to Earth, however, until Chang'e I enters the lunar orbit, he said.

The China National Space Administration said on its website yesterday that land- and sea-based surveillance posts, as well as four astronomical observatories, have kept watch over the satellite's progress since Saturday.

"According to the data received so far, all systems have been working normally," it said.

In the following 10 days, Chang'e I is scheduled to carry out three critical moves, the administration said.

Tomorrow, it will enter the Earth-moon transfer orbit. During this time, any mistakes made will result in the failure of the mission, the administration said.

On November 5, Chang'e I will attempt to enter a lunar orbit, at which time it will run the risk of either crashing into the moon or flying straight past it.

Finally, on November 7, the satellite will attempt to move into a much tighter orbit, circling just 200 km above the moon's surface.

Yang Duohe, chief engineer at the lunar probe program center, said Chang'e I will send back data collected during this section of its flight on December 18. If that is successful, all detectors fitted to the satellite will be turned on to enable a full scientific probe, he said.

As of 7 pm on Sunday, Chang'e I had circled the Earth five times in 96 hours, the space administration said.

Ji Gang, a designer with the lunar program, said by the time the satellite reaches it final orbiting position, it will have traveled a total of 1,585,219 km. It has so far journeyed 500,000 km.