Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa, 2018, Vol. 15, No. 6, pp. 90-105
Ways to decrease thermoelastic deformations of star trackers
G.A. Avanesov
1 , R.V. Bessonov
1 , N.N. Brysin
1 , A.S. Kvashnin
1 , V.E. Shevelev
1 1 Space Research Institute RAS, Moscow, Russia
Accepted: 23.11.2018
DOI: 10.21046/2070-7401-2018-15-6-90-105
Modern spacecraft with high-and ultra-high-resolution imaging equipment requires an accurate system for orientation of angular position in space. The main tool to determine the high-precision orientation is stellar sensors. One of the types of star trackers errors is caused by thermoelastic deformations. Identification of their causes is associated with the determination of sources of thermal energy accumulated by the structure in orbital flight. The paper presents the causes of thermoelastic deformations and their influence on the tracker angular turns. Data of full-scale operation of the instruments and calculation models are given. The analysis of thermal conditions and thermoelastic deformations is made by using the finite element method which allows a lot of necessary calculations to find the optimal solution with minimal thermoelastic deformations of the tracker. The method of calculation of thermoelastic deformations and estimation of angular displacements is described. The following approaches to the construction of thermostable structures of the instruments are analyzed: the choice of materials with the necessary physical properties, design solutions, the creation of conditions for minimizing the impact of the operating environment. The advantages and disadvantages of each approach are noted. Proposed measures to reduce thermoelastic deformations should be applied both in the design of the star orientation device and the spacecraft and its equipment.
Keywords: star tracker, solar radiation, thermoelastic deformations, thermal expansion coefficient, thermal conductivity, thermostability
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