China's first lunar probe, Chang'e-1, will reach the moon's orbit Monday morning and currently, it was traveling on the expected trajectory, scientists said Sunday.

Chang'e-1, following the instructions of the Beijing Aerospace Control Center (BACC), will carry out its first braking at perilune at about 11:00 AM Monday to slow down, so that it can be captured by the lunar gravity and become a circumlunar satellite, said Wang Yejun, chief engineer of BACC.

"The speed of Chang'e-1 can reach 2.4 km per second when it arrives at perilune, and it will likely fly away from the moon if the braking is not conducted in time," Wang said.

"The first braking at perilune is another key moment in the long journey of Chang'e-1," he said.

China's first lunar probe, Chang'e-1, named after a legendary Chinese goddess who flew to the moon, blasted off on a Long March 3A carrier rocket on October 24 from the Xichang Satellite Launch Center in southwestern Sichuan Province.

The probe completed its fourth orbital transfer late Wednesday afternoon, shifting out of its 120,000-kilometer orbit around the Earth and moving toward a 380,000-kilometer circumlunar orbit.

BACC successfully carried out an orbital correction for Chang'e-1 Friday morning to ensure that it travels on the pre-set orbit.

A second orbital correction scheduled for Sunday morning has been called off because it was "unnecessary" -- Chang'e-1 has been running accurately on the expected trajectory, a BACC scientist said.

"Currently, Chang'e-1 was traveling at a speed of more than 300 meters per second toward perilune, and all data show that the satellite is operating well," Tang Geshi, BACC scientist told Xinhua late Sunday afternoon.

"We're now studying how to ensure the success of the first braking for Chang'e-1," he said.

After the probe entered the moon's orbit, it would brake several more times to slow down, scientists have said.

It is scheduled to relay the first picture of the moon in late November and would then continue scientific explorations of the moon for a year.

The 2,350-kg satellite carried eight probing facilities, including a stereo camera and interferometer, an imager and gamma/x-ray spectrometer, a laser altimeter, a microwave detector, a high energy solar particle detector and a low energy ion detector.

It will fulfil four scientific objectives, including a three-dimensional survey of the Moon's surface, analysis of the abundance and distribution of elements on lunar surface, an investigation of the characteristics of lunar regolith and the powdery soil layer on the surface, and an exploration of the circumstance between the earth and the moon.

(Xinhua News Agency November 5, 2007)