Orbital Sciences Corporation

David A Steffy

Anthony D Robinson

Maria J Evans

Gregg E Burgess

The present invention provides a method and system for formationkeeping between two or more orbiting spacecraft by controlling the surface area of the spacecraft facing the direction of perturbative forces acting on the spacecraft. The actual position of each spacecraft is sensed and the distance between the spacecraft is computed. If this separating distance exceeds acceptable tolerances, the affected spacecraft are commanded to change their orientation so that the total surface area facing the direction of motion is altered. Alternatively, the total surface area of the spacecraft facing the direction of solar pressure can be altered. As a result, the forces acting on the spacecraft are altered which alters spacecraft position and velocity. In accordance with another aspect of the invention, surface area variations of individual spacecraft are used to maintain the planar separation between adjacent constellations of orbiting spacecraft at desired distances.

Method and system for formationkeeping between orbiting spacecraft by

The present invention comprises an axially arrayed helical antenna system adapted for use in a variety of broadcasting or receiving stations including a low Earth orbiting communication satellite station. The helical antenna array comprises a plurality of antenna structures each including at least one helical antenna element coaxially mounted on a common mounting structure with a separating distance between them. Each element is electromagnetically coupled to a corresponding element of the subsequent antenna structure in the array to form a separate, isolated antenna. A feeding means is included for supplying appropriately phase shifted signals to the elements that comprise each antenna. In addition, in accordance with the invention, additional independent antennas or other equipment or payload can be deployed in the separating distance between the arrayed antenna structures.

Axially arrayed helical antenna

A satellite has two solar array panels which are moveable between a closed configuration and an open configuration. The solar array panels are pivotably mounted on hinges attached along the top and bottom of the satellite and extend outwardly from the top and bottom of the satellite in the open configuration. The height of the perimeter sidewall is selected such that the satellite has a generally oblate configuration. Each solar array panel has a surface area substantially equal to that of the satellite cross-sectional area. The hinges are mounted on pintles extending from a solar array drive motor which rotates the solar panel about the axis defined by the pintles to provide one axis sun tracking. The solar array panels are pivoted about the axes of the hinges until substantially parallel to the top and bottom of the satellite to form a compact, stackable configuration of the satellite for stowage. Three couplers positioned along the perimeter wall couple the satellite to similarly configured satellites within the fairing of a launch vehicle. The coupled satellites form a stack having three load-bearing columns consisting of the satellite couplers. In the stacked configuration, the couplers of one satellite are attached to the couplers of adjacent satellites by bolts restrained within non-explosive separation nuts. Pre-loaded compression springs extend between the couplers of adjacent satellites. After the stack of satellites separates from the fairing, each satellite is successively deployed from the stack, starting with the top-most satellite. Deployment begins by activating the non-explosive separation nuts in the couplers of the top-most satellite. Thereafter, the pre-loaded compression springs extending between the coupling devices of the top-most satellite and the subjacent satellite (or, for the bottom-most satellite, the subjacent booster stage) accelerate the top-most satellite away from the stack and booster stage.

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Herndon, VA, United States of America

David A Steffy