Subterranean target steering strategy
First Claim
1. A method for targeting the payload beam of a satellite in a geosynchronous earth orbit toward an intended service area having known geographical dimensions, comprising the steps of:
- determining a subterranean target point, the target point being at least 100 kilometers below the earth'"'"'s surface and distinct from the earth center;
orienting the satellite payload toward the subterranean target point; and
maintaining the payload beam orientation during orbit using an on board attitude control system.
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Accused Products
Abstract
A method for steering the payload beam of a satellite in a non-geostationary orbit toward an intended service area having known geographical dimensions in order to obtain improved pointing performance with a corresponding reduction in the demand on onboard hardware and software systems. The method comprises the steps of determining a subterranean target point and a direction fixed in the payload beam, calculating the orientation that points the payload beam direction through the subterranean target point, and maintaining this payload beam orientation using an on-board attitude control system.
17 Citations
16 Claims
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1. A method for targeting the payload beam of a satellite in a geosynchronous earth orbit toward an intended service area having known geographical dimensions, comprising the steps of:
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determining a subterranean target point, the target point being at least 100 kilometers below the earth'"'"'s surface and distinct from the earth center; orienting the satellite payload toward the subterranean target point; and maintaining the payload beam orientation during orbit using an on board attitude control system. - View Dependent Claims (2, 3, 4, 5)
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6. A method for steering the payload beam of a satellite in a non-geostationary earth orbit toward an intended service area having known geographical dimensions, comprising the steps of:
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determining the position of a subterranean target point, the target point being at least 100 kilometers below the carth'"'"'s surface and distinct from the earth center; selecting a target vector fixed in the payload pattern; determining the satellite position; directing the target vector toward the target point; and maintaining the target vector pointing toward the target point using an on-board attitude control system. - View Dependent Claims (7, 8, 9)
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10. A method for targeting the payload beam of a satellite in a geosynchronous earth orbit toward an intended service area having known geographical dimensions, the payload beam includes a boresight, and further wherein an orbit inclination angle, the northern and southern region extremes of the intended service area, and the payload beam half-angle are all known, said method comprising the steps of:
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determining a subterranean target point, the target point being distinct from the earth center; orienting the satellite payload beam toward the subterranean target point; maintaining the payload beam orientation during orbit using an on board attitude control system; calculating a northern payload extreme when the satellite is in a first known orbit location; aligning the northern payload extreme with the northern region extreme; calculating a first subterranean point at which the satellite boresight intersects the earth equatorial plane; calculating a southern payload extreme when the satellite is in a second known orbit location; aligning the southern payload extreme with the southern region extreme; calculating a second subterranean point at which the satellite boresight intersects the earth equatorial plane; comparing the first subterranean point to the second subterranean point; and choosing the subterranean target point based on the comparison. - View Dependent Claims (11, 12, 13)
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14. A method for steering the payload beam of a satellite in a non-geostationary earth orbit toward an intended service area having known geographical dimensions, wherein the satellite is in a geosynchronous orbit having an inclination angle of ten degrees or less, the method comprising the steps of:
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determining the position of a subterranean target point, the target point being at least 100 kilometers below the earth'"'"'s surface and distinct from the earth center and wherein said step of determining the position of the subterranean target point further comprises the steps of; calculating the position of the target vector when the satellite is in its preferred pointing attitude at different satellite locations within the orbit to obtain a set of target vectors; and choosing the subterranean target point at a point that minimizes a payload pointing metric over the set of target vectors; selecting a target vector fixed in the payload pattern; determining the satellite position; directing the target vector toward the target point; and maintaining the target vector pointing toward the target point using an on-board attitude control system. - View Dependent Claims (15, 16)
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Specification