China pursues 'zero window' launch for lunar probe

BEIJING - China will strive to launch its Chang'e-3 lunar probe at the optimal time within the launch window, the Xichang Satellite Launch Center said on Friday.

China is scheduled to launch the probe in early December. It will be the first time for a Chinese spacecraft to soft-land on the surface of an extraterrestrial body.

The center said it will pursue a "zero window" launch for the mission, referring to a launch at a pre-determined optimal time for the probe to reach its intended target. If a "zero window" launch is not achieved on time, it must be delayed until the next launch window.

If a zero window launch is achieved, Chang'e-3 will not need to make trajectory correction before entering the pre-selected orbit, and fuel can be saved during orbital transfer, according to the center.

The zero window launch can be achieved through timing control of the rocket ignition, said Zhao Ming, deputy commander in charge of China's lunar program launching site system.

However, the launch will be influenced by a variety of factors, including the project's targets, the motion of the earth, moon, and sun, as well as the weather conditions at the launch site, Zhao added.

"Achieving a zero window launch is difficult, and success will reflect the ability for the project's different systems to coordinate and cooperate," Zhao said.