Microgravity measurement in space using imaging techniques.
Steedman, Mark John
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The proposal is made that very small changes in gravitational field could be detected by monitoring a cell of heated fluid. Variations in gravity would be observed by their effect on the convection in the fluid cell. It is proposed that the convection patterns be observed by using an interferometer to image the temperature gradient in the fluid by utilising the effect of temperature variations on the refractive index of the fluid. It was proposed that this system may be able to detect changes in the Earth's gravitational field from orbit. The possibility of using the NASA GAS programme to perform a space flight test of this proposal was suggested. Activities in this programme were therefore surveyed and a proposal made. The primary experimental results were recorded in the form of convection images which were later processed on the ground to extract information. Research has been carried out in this area as investigation has shown that existing image processing techniques are not suitable to process the anticipated fringe images. Meanwhile design and development of a GAS experiment was performed. This was undertaken in liaison with NASA in order to achieve the required safety approvals for flight. Subsequently the flight experiment was performed aboard the Space Shuttle Endeavour during the STS-77 mission launched on the 19th May 1996. As a result of this project an image processing system for the analysis of interferogram images of convection has been developed and an experiment to image convection in microgravity, with a view to analysing its use for the detection of changes in gravity has been performed.