Spin motion of the AJISAI satellite derived from spectral analysis of laser ranging data

The spin rate of the geodetic satellite AJISAI was derived through a spectral analysis of laser range data obtained by precise high-return-rate tracking stations. This new analysis method utilizes the directional dependence of the target optical depth resulting from the sparse distribution of corner cube reflectors on the satellite surface. The third and sixth harmonics of the spin rate were found to be dominant in the pass-by-pass spectral analysis of the full-rate range residuals from multiphoton laser ranging systems. Accumulating hundreds of passes, the analysis results gave the slowdown of AJISAI's spinning from 1997 to 1998. Its trend was almost identical to the conventional flash observation. Although the spin rate derived from this method was not as precise as the conventional one, it can provide global spatial coverage and continuous time coverage to monitor the spin motion. This is a new approach to research satellite orientation and orbit and is applicable to other satellites.