Design of a new remote control system for microgravity facilities on boardthe International Space Station: Preliminary results

The paper deals with the preliminary design of a new system for Telescience operations of microgravity experimentation on-board the International Spac e Station. The system represents an innovative implementation of new telecommunication system that combined with on-board computer, is able to provide complement ary link between the investigator on-ground and the facilities on-board. This new concept is aimed to carry out the following tasks: . to reduce as much as possible the period of loss of the signal, so as to guarantee an almost continuous and real-time control of the experiment; . to reduce the complexity of the network which routes the signal from ISS to the Investigator and vice versa; . to simplify the access procedure to the scientific payloads. In order to obtain such results the system has been designed to be operated with the existing commercial telecommunication satellites for mobile users . The selection of these platforms imposed the utilisation of low bit rate channels, that, however, using data extraction techniques, are compliant wi th large part of the planned experiments. This scenario has been defined al so taking into account a comparative analysis of the possible constellation suitable for this utilisation. A major problem due to the installation on a space platform of a transponde r conceived for Earth mobile users is the magnitude and the rate of Doppler shift between the platform and the satellites of the constellation. The re quired modifications to the transponder have been analysed and a solution i s proposed. Utilisation of low bit rate channels represents a strong constraint for dat a stream, since for a certain number of microgravity experiments the most r elevant information is carried in video images. A video link, on the other hand, is an extremely demanding resource, often not available during the co mplete mission, but only during very limited periods of coverage. From thes e considerations stems the idea to implement on-board a system able to extr act most significant scientific information from experiment images and to t ransmit only this information over the link (available during all the missi on time). In addition, other systems on-ground receive the data and are abl e to reconstruct a "virtual" image on the basis of the extraction algorithm used. In this paper, techniques that can be applied to this process of "video inf ormation extraction" are analysed and discussed. As a test case two algorit hms of data extraction from video images of Fluid Science experiments have been developed, together with the on-ground reconstruction software. The al gorithms have been tested using images of an experiment carried out during Spacelab LMS mission and the results obtained are presented. Their implemen tation has shown that this system is suitable for the real-time experiment control, also taking into account that the scientific images can be stored on-board and analysed post-flight for a more accurate scientific evaluation . (C) 2001 Published by Elsevier Science Ltd.