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Paper: A Rotating Space Interferometer with Variable Baselines and Low Power Consumption
Volume: 194, Working on the Fringe: Optical and IR Interferometry from Ground and Space
Page: 385
Authors: Gezari, D.
Abstract: A large (100-m class) multi-aperture imaging spatial interferometer for space astronomy applications presents numerous daunting technical design challenges, not the least of which is satisfying the requirement that power consumption for the maneuvering the spacecraft be reduced to levels which can be provided by stored or collected energy (fuels, propellants, solar electric power, etc.). This requirement can be severe in the case of a rotating interferometer with variable baselines because large amounts of power could be required to counteract inertial effects, primarily centrifugal force on the collectors in a rotating structure. The SPECS submillimeter interferometer concept being studied at Goddard would rely on tethers to hold three 3-meter apertures in position radially against centrifugal force on the rotating system. But tethers have significant limitations which might prove unsurmountable. Unfortunately, changing the dimensions of a simple rotating structure can cause its angular velocity to change since angular momentum is conserved. A design where the baselines change uniformly while the angular velocities of the components remained unchanged would be optimum. An alternate concept is presented here for a three-aperture,variable baseline interferometer, where the telescope baselines change continuously as a result of the uniform rotation of rigid structural elements. Since the components rotate about their respective centers of gravity and all angular velocities are constant, no fuel (energy) need be expended to compensate for rotational effects (forces), station keeping, changing baselines or maintaining acceptable baseline scan rates. Reasonably uniform u,v plane coverage and integration times can be approximated with various combinations of constant angular velocities and phases of the rotating structural elements.
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