中继卫星(TDRS)支持环月探测器的研究

On a Tracking and Data Relay Satellite (TDRS) Tracking a Lunar satellite

给出了基于轨道根数的跟踪与数据中继卫星(TDRS)对月球探测器的可视算法,分析和比较了地面站和TDRS对月球探测器的测控跟踪能力．结果表明,与依靠地面站相比,使用TDRS后,在不考虑月球遮挡情况下,对环月探测器的测控覆盖率可由50％提高到99％．存在最大月球遮挡时也能达到60％,大大提高了对环月探测器的测控能力．最后讨论了TDRS跟踪环月探测器对TDRS卫星平台的要求,提出了地面站与TDRS相结合的测控方案．在当前TDRS天线运动范围受限情况下,仍能实现对月球探测器的大范围测控覆盖率．

China has implemented its change engineering. The first lunar satellite will be lunched in 2007. When it is on orbit and tracked and controlled by a ground-based TTC station, the zone of exclusion caused by the earth＇s rotation is about 50%. Although the coverage can be improved by scattered more earth stations along the longitude, the improvement effect is limited with the restriction of Chinese territory. Obviously, an on-orbit tracking and data relay satellite can enlarge the coverage. Based on the orbital elements, an algorithm to calculate the terms for a TDRS tracking a lunar satellite is presented here. Then the space coverage of a lunar satellite tracked by an earth station or a TDRS is computed. Their results show that compared with the tracking coverage of 32% or 50% made by an earth station, a TDRS can cover a lunar satellite by 61% with lunar exclusion or 90% without lunar exclusion. When a lunar satellite is tracked by a TDRS rather than an earth satellite, some extra requirements are added to the TDRS＇ antenna movement. These requirements are beyond the capability of the current on-orbit TDRS, which is designed for tracking low earth satellites. Finally, with the help of an earth station and a careful scheduler, a proposal is presented to further enlarge the tracking coverage for a current on-orbit TDRS tracking a lunar satellite.