Advancing tests of relativistic gravity via laser ranging to Phobos
Advancing tests of relativistic gravity via laser ranging to Phobos
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DOI：
10.1007/s10686-010-9199-9
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发表时间：
2010-03
影响因子：
3
通讯作者：
S. Turyshev;W. Farr;W. Folkner;A. Girerd;H. Hemmati;T. Murphy;James G. Williams;J. Degnan
中科院分区：
文献类型：
--
作者：
S. Turyshev;W. Farr;W. Folkner;A. Girerd;H. Hemmati;T. Murphy;James G. Williams;J. Degnan
火卫一激光测距（PLR）是一项太空任务的概念，旨在推进太阳系相对论引力的测试。PLR的主要目标是测量由爱丁顿参数（Eddington parameterγ）表示的太阳周围空间的曲率，精度达到107的两倍，从而将目前的最佳结果提高两个数量级。其他任务目标包括测量引力常数的时间变化率，1.5天文单位距离的引力平方反比定律的Gand，每项都有两个数量级的改进。科学参数将通过激光测距测量地球站和火卫一上的主动激光转发器之间的距离来估计，该激光转发器能够达到毫米级的距离分辨率。火卫一上的应答器以1khz的频率发送0.25 mj， 10ps的脉冲，并通过一个12厘米的孔径从地球上接收异步的1khz脉冲，这将允许即使在最大距离也能超过每秒一个光子的连接。50 ps的总测量精度需要几百个光子，平均到1毫米（3.3 ps）的范围精度。现有的卫星激光测距（SLR）设备——经过适当的增强——可能能够参与PLR。由于火卫一的轨道周期约为8小时，因此每个天文台都可以保证每个地球日都能看到火卫一的仪器。考虑到目前的技术准备水平，PLR可以在2011年启动，并在2016年发射，进行为期3年的科学操作。我们讨论了PLR的科学目标、仪器和任务设计。我们还介绍了为支持该任务的主要目标而进行的科学模拟的细节。
Phobos Laser Ranging (PLR) is a concept for a space mission designed to advance tests of relativistic gravity in the solar system. PLR’s primary objective is to measure the curvature of space around the Sun, represented by the Eddington parameterγ, with an accuracy of two parts in 107, thereby improving today’s best result by two orders of magnitude. Other mission goals include measurements of the time-rate-of-change of the gravitational constant,Gand of the gravitational inverse square law at 1.5-AU distances—with up to two orders-of-magnitude improvement for each. The science parameters will be estimated using laser ranging measurements of the distance between an Earth station and an active laser transponder on Phobos capable of reaching mm-level range resolution. A transponder on Phobos sending 0.25-mJ, 10-ps pulses at 1 kHz, and receiving asynchronous 1-kHz pulses from earth via a 12-cm aperture will permit links that even at maximum range will exceed a photon per second. A total measurement precision of 50 ps demands a few hundred photons to average to 1-mm (3.3 ps) range precision. Existing satellite laser ranging (SLR) facilities—with appropriate augmentation—may be able to participate in PLR. Since Phobos’ orbital period is about 8 h, each observatory is guaranteed visibility of the Phobos instrument every Earth day. Given the current technology readiness level, PLR could be started in 2011 for launch in 2016 for 3 yr of science operations. We discuss the PLR’s science objectives, instrument, and mission design. We also present the details of science simulations performed to support the mission’s primary objectives.