Single axis correction for orbit inclination
First Claim
1. A method of orienting a payload of an orbiting spacecraft including a bias momentum storage means to maintain a desired pointing profile other than at Earth center in a presence of orbit inclination, the method comprising the steps of:
- determining a cone which is traced in inertial space by a pitch axis of the payload in order to maintain the desired pointing profile throughout an orbit;
orienting a bias momentum vector of the spacecraft at an attitude which lies in the cone and outside of a plane spanned by an orbit normal vector and an equatorial normal vector; and
varying an angle between the payload pitch axis and the bias momentum vector about a single body-fixed axis skewed in a roll-yaw plane by an angle variation means to maintain the payload pitch axis in the desired pointing profile;
wherein the attitude of the bias momentum vector and the single body-fixed axis are chosen to be consistent with maintaining the desired pointing profile.
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Accused Products
Abstract
A method and system of orienting a payload of an orbiting spacecraft (14) to maintain a desired pointing profile in the presence of orbit inclination. A cone (12) is determined which is traced in inertial space by a pitch axis of the payload to maintain the desired pointing profile throughout an orbit. A bias momentum vector of the spacecraft (14) is oriented at an attitude which lies along the cone (12). The attitude has a nonzero angle with respect to a plane spanned by an orbit normal vector and an equatorial normal vector. The payload is rotated about a single body-fixed axis perpendicular to the pitch axis to align the pitch axis along the cone (12). As a result, the desired pointing profile is maintained throughout the inclined orbit.
47 Citations
18 Claims
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1. A method of orienting a payload of an orbiting spacecraft including a bias momentum storage means to maintain a desired pointing profile other than at Earth center in a presence of orbit inclination, the method comprising the steps of:
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determining a cone which is traced in inertial space by a pitch axis of the payload in order to maintain the desired pointing profile throughout an orbit; orienting a bias momentum vector of the spacecraft at an attitude which lies in the cone and outside of a plane spanned by an orbit normal vector and an equatorial normal vector; and varying an angle between the payload pitch axis and the bias momentum vector about a single body-fixed axis skewed in a roll-yaw plane by an angle variation means to maintain the payload pitch axis in the desired pointing profile; wherein the attitude of the bias momentum vector and the single body-fixed axis are chosen to be consistent with maintaining the desired pointing profile. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 14)
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10. A system for orienting a payload of an orbiting spacecraft including a bias momentum storage means to maintain a desired pointing profile other than at Earth center in a presence of orbit inclination, the system comprising:
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a set of orbit and attitude sensors to determine an orbit and an attitude of the spacecraft; a processor which determines a cone which is traced in inertial space by a pitch axis of the payload in order to maintain the desired pointing profile throughout the orbit; an external torquer responsive to the processor to maintain an orientation of a bias momentum vector of the spacecraft at an attitude which lies along the cone and lies outside a plane spanned by an orbit normal vector and an equatorial normal vector; and angle variation means responsive to the processor for varying an angle between the pitch axis and the bias momentum vector about a single body-fixed axis skewed in a roll-yaw plane to maintain the pitch axis in the desired pointing profile; wherein the attitude of the bias momentum vector and the single body-fixed axis are chosen to be consistent with maintaining the desired pointing profile. - View Dependent Claims (11, 12, 13, 15, 16, 17, 18)
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Specification