November 11, 2022, Friday, 03:00PM (GMT+03.00, Moscow)

Abstract:

The purpose of the work is to increase the efficiency (informative value) of observations of objects under study from spacecrafts. Pointing the scientific instruments at terrestrial or celestial targets is achieved by turning the spacecrafts or using special steerable platforms onboard them. The following more specific types of problems are considered:

1. Optimal (according to the specified criteria) planning of observations that require tracking several targets (listed in catalogues) using several separately controlled scientific instruments which are installed onboard spacecrafts.

To find for every of the instruments an optimal program of transitioning from tracking one target to tracking another target a precise solution is suggested. It uses methods of linear integer programming to select optimal combinations of observation programs out of sets of all the possible programs, which have been pre-generated for each instrument taking into account the specified constraints. If precise solutions involve an unacceptable amount of computations, approximate algorithms are used. They are mainly based on genetic meta-heuristic.

Presented methods have been implemented within special software supporting experiments onboard the International Space Station (ISS). Cameras and spectrometers can be pointed in automatic mode simultaneously by several steerable platforms. ISS crew members can also take part in the imaging by pointing cameras at the targets with the aid of special hardware and software.

2. Effective pointing one scientific instrument at one target. In the work the conditions are considered when there is sufficient indeterminacy in the data on the relative positions of the instrument and the target.

This problem is solving by using artificial dispersion while pointing the sensitive axis of the instrument. The results of artillery mathematical theory are applied for the determination of the dispersion parameters. Special ground and onboard software have been developed. It allows to increase the probability of successful shooting when the camera is pointed toward the ground objects both automatically and manually onboard the ISS.

3. Determination and refinement of the spacecraft coordinates and orbital data using pictures of the planetary surface taken from the spacecraft.

The geometrical and computational methods involved in solving this problem are presented with examples of their using for the ISS position and orbit determination. Besides that, several pictures of the lunar surface taken by the USA astronauts have been used for the estimations of the positions of the American lunar modules.

Optimal tracking several targets (problem 1) partly depends on algorithms of tracking every of the targets by every of the instruments. For their part, these algorithms depend on, among other factors, the spacecraft orbit accuracy determination. A low accuracy may require using artificial dispersion (problem 2) with the corresponding parameters or refinement of orbital data (problem 3).

The report is based on the thesis for the degree of Candidate of Sciences in Engineering (the supervisor is Mikhail Yu. Belyaev).