EXTENSION TO PASSIVE SOUNDER STUDY COMMON ATTITUDE POINTING SYSTEM (CAPS)

摘要

A Common Attitude Pointing System (CAPS) is described which could satisfy the scan/stabilisation requirements of most passive atmospheric sounders on Spacelab.n• The capabilities and characteristics of other pointing systems are considered and their use rejected (though NASA's Miniaturised Pointing Mount merits some further consideration).n• Various options are considered for the control system and size of CAPS;a medium-sized platform (to carry about three averaged-sized instruments) is reckoned to offer the most effective solution when mass, area, power, cost, etc., are taken into account.n• A design is presented for a 'floating reference' (i.e. entirely gimballed) system which, in an early version, would carry a package of instruments weighing about 200 kg. Attitude and rate measurements, elevation and azimuth scanning, and roll stabilisation would be supplied to the package.n• The instruments could be mounted within a canister (e.g. 0.8m x 0.8m cross-section and about lm length) providing a controlled thermal environ¬ment.n• This early version of CAPS would itself weigh about 135 kg (or about 100 kg if the thermally-controlled canister were deleted leaving just a strong ring and platform on which to mount larger-than-average instruments such as a microwave antenna). Power consumption of CAPS itself would be about 70W mean.n• The early versions of CAPS could be extended in size (to carry more or larger instruments) and in capability (e.g. attitude measurement and stabilis¬ation in all 3 axes). A design is presented for a large CAPS (2m x lm cross-section;2m overall length of canister) for later Spacelab missions. Since the mass and power consumption of the early version are less than half those of the later version, a more effective approach may be to use two medium-sized CAPS rather than develop a large CAPS.n• The estimated time to develop CAPS for 1st Spacelab is about l years (subsequent to further definition studies of the concept).n• Estimates are also presented to confirm that a CAPS facility could be cost-effective in the long term.n• An alternative 'fixed-reference' system is also discussed which would provide only attitude and rate information to instruments mounted on a fixed platform, each with its own scan assembly. The mass/power/cost of this facility would all be about half those of the floating reference system.