China's lunar probe Chang'e 1 successfully carried out its first orbital
correction today morning in a bid to ensure that it travels on the pre-set
orbit.
Instructions for the orbital correction was issued by the Beijing Aerospace
Control Center (BACC) at 10:25am today, when two small engines on Chang'e 1 were
ignited to slightly modulate its trajectory.
Eight minutes later, the two engines stopped working and the orbital
correction completed.
"Data show we have reached our expectation through the orbital correction,"
said Wang Yejun, the BACC's chief engineer.
Chang'e 1 now is moving the earth-moon transfer orbit with the apogee of
about 380,000 km and it is expected to reach the moon's orbit at 11:25am Monday.
The orbital correction, which was planned to be conducted yesterday, was
canceled as the probe was traveling on the expected trajectory in an "unexpected
precisely" way after it left the earth orbit late Wednesday, said Wang.
"That's also the reason why we didn't employ the main engine on the Chang'e 1
for the first orbital correction, because it is not necessary and it also saves
energy for the orbiter's future operation," he said.
A second orbital correction might be carried out Sunday, said Wang.
Pang Zhihao, a researcher with the China Academy of Space Technology, said
orbital correction is necessary to prevent an orbiter from veering off its
projected course.
"An aircraft faces many disturbances, such as gravitation from celestial
bodies, when it travels in space, so we have to carry out corrections to ensure
it moves on the right track," said Pang.
"Just like driving a car, we must keep turning the steering wheel to ensure
the car running right on the roadway," said Pang.
Chang'e-1, named after a mythical Chinese goddess who, according to legend,
flew to the moon, blasted off on a Long March3A carrier rocket at 6:05pm of Oct.
24 from the Xichang Satellite Launch Center in the southwestern province of
Sichuan.
It entered earth-moon transfer orbit on Wednesday and is expected to arrive
at the moon's orbit at 11:25am on Nov. 5.
Chang'e 1 will brake several times then to slow down so that it can be
captured by the lunar gravity and become a real circumlunar satellite.
It would relay the first picture of the moon in late November and would then
continue scientific explorations of the moon for a year.
China's lunar orbiter project has cost 1.4 billion yuan (US$187 million)
since research and development of the project was approved at the beginning of
2004.
The launch of the orbiter marks the first step of China's three-stage moon
mission, which will lead to a moon landing and launch of a moon rover around
2012. In the third phase, another rover will land on the moon and return to
earth with lunar soil and stone samples for scientific research around 2017.
China carried out its maiden piloted space flight in October 2003, making it
only the third country in the world after the Soviet Union and the United States
to have sent men into space. In October 2005, China completed its second manned
space flight, with two astronauts on board.