Method of In-Situ Measurements of the Radiation Intensity Profile in the Spacecraft Zone for a Ground-Based Satellite Laser Ranger

E. V. Burmistrov, I. A. Elantyev, S. A. Kononaeva, A. O. Murkin

Transactions of IAA RAS, issue 58, 11–16 (2021)

DOI: 10.32876/ApplAstron.58.11-16

Keywords: satellite laser ranger, radiation intensity profile, angle noise, flyby mode

Abstract

The reason for this work was the idea of D.Eng.Sc. V. P. Vasilyev, expressed in a private conversation and dealing with carrying out an experiment on locating a spacecraft in a flyby mode: the rotary support is stationary and set to the anticipated trajectory point, the target object passes the directional radiation pattern during the laser ranging session. The guidance system without angle noise will provide for correspondence of the response density at the center of the radiation pattern to the energy calculation. The problem is solved by averaging of the statistical data accumulated in a series of successive flybys. The main task of this work is to implement location flyby mode on serial product. The experimental part of the work was carried out at the “Sazhen-TM” stations, while the first sessions which are significant for statistics were accumulated at the “Svetloe” observatory. The method of motion program forming consisted of interpolating of angular target designations and time scaling; the range forecast remained unchanged. The location interval of the relevant range signal from the GLONASS spacecraft was 10 seconds, which corresponds to the time of 5 consecutive flybys. At the same time the signal-to-noise ratio proportionally decreased to the portion of flybys of the total tracking time (8–15 %), which did not interfere with reliable signal detection in daytime location mode. The fact used here is that at the design stage of “Sazhen-TM” system, the signal-to-noise ratio has been set based on the need to obtain unbiased range estimates, which are significantly higher than the signal-to-noise threshold required for signal detection and there is a reserve for this parameter. The implementation of the flyby mode idea has led to the development of a tool — a method of in-situ measurements of the radiation intensity distribution over the cross section of the laser beam in the orbital zone of the spacecraft in proportion to the rate of reflected signals registered in the single-electron ranging mode when the spacecraft passes the radiation zone. The target profile of the radiation intensity is the result of the tracing of the distribution density of range measuring events moments based on their implementation in a series of central flybys with the dimension of the argument corresponding to angular coordinates in proportion to the angular velocity of the spacecraft along the tracking.

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