Controlling steerable platforms to point scientific instruments at survey targets in the uragan experiment onboard the international space station

At present, a number of scientific experiments onboard the International Space Station (ISS) are being run with the use of Steerable Pointing Platforms (SPP). The use of SPP is especially important because of the existing constraints on the ISS attitude maneuvers [1]. Owing to low level of momentum available from Control Moment Gyros on the US orbital segment, the ISS flies in quasiorbital attitude. Therefore, it is virtually impossible to point instruments that are rigidly attached to the ISS towards their survey targets by changing ISS attitude. This flight mode of the ISS calls for the use of SPPs onboard the station and development of control algorithms for turning the SPPs in order point them towards their survey targets. Since survey target catalogues list thousands of items, while resources available for implementing the possible pointing options are limited, there arises the problem of optimizing control during pointing of scientific equipment towards the survey targets. The paper describes a solution to this problem which uses a pointing system for video spectrometric equipment, which is being developed within the framework of an Earth studies experiment Uragan which is being carried out onboard the ISS Russian Segment (RS).