Friday, September 10, 2010

Abort trajectory for manned lunar landing missions

XiaoNing Xi, WenDe Huang & Wei Wang

Technological Sciences
Volume 53, Number 10

The safety of astronauts is always of dominant importance, though the major objectives of the manned lunar landing mission are to land the astronauts to the moon, explore the surface, and return safely to the earth. This safety requirement demands an abort and a safe return when an emergency occurs. However, it is difficult to send another spacecraft to save the spacecraft in the emergency, because it is flying away from the earth either on the way to the moon or too far from the earth when arriving at the moon.

Consequently, the safe return can only rely on the spacecraft itself to transfer the trajectory onto an abort trajectory. Since the trajectory design is an upper work of the mission design [1], the abort capability should be considered in the design of manned landing mission trajectory. That is, abort trajectory should be designed before a manned landing mission is initialized.

Although the abort is usually not carried out, the design of abort trajectory is as important as the normal mission trajectory, especially in the sense of ensuring the safety of astronauts. American scholars have studied the abort for manned lunar mission as many as the normal mission, which will be described in detail below.

After the CE-1 was successfully implemented, China’s manned lunar landing program will also be accomplished consequentially in the near future. In this paper, we review the experience of the manned lunar landing mission, as well as summarize ourselves long-term research in this area, especially the studies on the mission trajectory design for manned lunar landing, abort trajectory design and launch window since the year of 2008.

In this review, the mission abort studies of America’s Apollo program are described in the next section. Then the essential elements of abort, which include the failures that result in an abort, the abort trajectory that returns the crew to the earth, thrust system that realizes the abort, navigation and guidance system, and life support system, are analyzed.

To that end, the requirements of an abort and the rational selection of the abort trajectory are mainly discussed during various flight phases of the mission. In addition, the two primary constraints of abort, the time of flight and energy requirement, are discussed. In order to make a trade-off between time of flight and energy requirement, an optimum method that uses multi-impulse abort is proposed. Lastly, suggestions of abort research are given for China’s future manned lunar landing mission.

Download and read the research (pdf), HERE.

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