Spacecraft configuration and attitude steering method for highly inclined orbit (HIO) communications
AssigneeLockheed Martin Corporation
InventorsGen-Sen James Cheng, Neil Evan Goodzeit
Life of this patent
Estimating the term…
Abstract
A method for controlling a geosynchronous spacecraft. A yaw axis and a roll axis of the spacecraft are oriented parallel to the earth equatorial plane. A coordinate frame of a payload is rotated about a minus roll axis of the spacecraft at an angle equivalent to an orbit inclination of the spacecraft, thereby maintaining elements of a payload pointing toward a desired region on the earth. A spacecraft attitude is corrected to maintain the payload elements pointing at the desired region on the earth.
Claims45
A method for configuring and operating a spacecraft in an orbit that is inclined with respect to the earth's equatorial plane, wherein the spacecraft includes at least a solar array and radiator panels, and operates for at least a portion of the orbit designated as a service arc, the method comprising:
- nominally orienting a yaw axis and a roll axis of the spacecraft such that the radiator panels are substantially parallel to the earth equatorial plane and a rotation axis of the solar array is substantially parallel to the earth pole axis;
- configuring the spacecraft with a coordinate frame of a payload rotated and fixed about the roll axis of the spacecraft at an angle equivalent to about an orbit inclination of the spacecraft so as to maintain a desired degree of a payload pointing toward a desired region on the earth's surface;
- and
- correcting a spacecraft attitude over at least a portion of the service arc with respect to the nominal orientation to maintain at least a portion of the desired degree of payload pointing toward the desired region on the earth's surface.
A method for configuring and operating a spacecraft in an inclined orbit, wherein the spacecraft comprises at least a solar array and one or more radiator panels, and operates for at least a portion of the orbit designated as a service arc, the method comprising:
- nominally orienting the spacecraft so that at about orbit apogee, a yaw axis and a roll axis of the spacecraft is oriented such that the one or more radiator panels are substantially parallel to the earth equatorial plane, and a rotation axis of the solar array is oriented substantially parallel to the earth pole axis,;
- configuring the spacecraft with a payload rotated and fixed about an axis of the spacecraft at an angle equivalent to about an orbit inclination of the spacecraft, so as to maintain a desired degree of a payload pointing toward a desired region on the earth's surface;
- and
- correcting a spacecraft attitude over at least a portion of the service arc with respect to the nominal orientation to maintain at least a portion of the desired degree of payload pointing toward the desired region on the earth's surface.
A spacecraft operable in an inclined orbit with respect to the earth's equator, the spacecraft operable for at least a portion of the orbit designated as a service arc, the spacecraft comprising:
- at least one solar array rotatable about a single axis;
- at least one thermal radiator;
- at least one payload antenna rotated and fixed about a spacecraft coordinate frame, wherein the rotation angle of the payload antennas is substantially similar to an inclination of the orbit of the spacecraft so as to maintain a desired degree of a payload antenna pointing toward a desired region on the earth's surface;
- and
- attitude adjusters adapted to adjust the attitude of the spacecraft;
- wherein the spacecraft is configured such that at orbit apogee the spacecraft has a nominal orientation in which the at least one solar array is substantially parallel to the earth pole axis, and the at least one thermal radiator is facing in a north-south direction;
- and
- wherein the attitude adjusters are adapted to correct the spacecraft attitude over at least a portion of the service arc with respect to the nominal orientation to maintain at least a portion of the desired degree of payload antenna pointing toward the desired region on the earth's surface.
A satellite constellation, comprising:
- a plurality of satellites operable to transmit digital audio broadcasts, the satellites being arranged in orbits inclined in the range of about 40 degrees to about 65 degrees, the satellites operable for at least a portion of their orbits designated as service arcs, each of the satellites comprising:
- at least one solar array rotatable about a single axis;
- at least one thermal radiator;
- at least one payload antenna rotated and fixed about a satellite coordinate frame, wherein the rotation angle of the payload antenna is substantially similar to an inclination of the orbit of the satellite so as to maintain a desired degree of a payload antenna pointing toward a desired region on the earth's surface;
- and
- attitude adjusters adapted to adjust the attitude of the satellite;
- wherein the satellites are configured such that at orbit apogee each of the satellites have a nominal orientation in which the at least one solar array is substantially parallel to the earth pole axis, and the at least one thermal radiator is facing in a north-south direction;
- and
- wherein the attitude adjusters of each of the satellites are adapted to correct the satellite's attitude over at least a portion of the service arc with respect to the nominal orientation to maintain at least a portion of the desired degree of payload antenna pointing toward the desired region on the earth's surface.
A method for configuring and operating a spacecraft in an orbit that is inclined with respect to the earth's equatorial plane, wherein the spacecraft includes at least a solar array and radiator panels, and operates for at least a portion of the orbit designated as a service arc, the method comprising:
- nominally orienting a yaw axis and a roll axis of the spacecraft such that the radiator panels are substantially parallel to the earth equatorial plane and a rotation axis of the solar array is substantially parallel to the earth pole axis;
- configuring the spacecraft with a coordinate frame of a payload rotated and fixed about the roll axis of the spacecraft at an angle equivalent to about an orbit inclination of the spacecraft so as to maintain a desired degree of a payload pointing toward a desired region on the earth's surface;
- and
- correcting a spacecraft attitude over at least a portion of the service arc with respect to the nominal orientation to maintain at least a portion of the desired degree of payload pointing toward the desired region on the earth's surface, the step of correcting further comprising:
- calculating first beam center unit vectors based on a data for a spacecraft position in the vicinity of an orbit apogee in a nominal target payload reference frame, wherein each first beam center vector represents at least an approximation of a line-of-sight from the spacecraft to the center of a beam on the earth's surface;
- calculating second beam center unit vectors in a nominal target payload frame based on data for a spacecraft position in the vicinity of the service arc;
- calculating a matrix of beam center pointing errors based on a combination of the first and second beam center vectors;
- calculating a composite matrix that includes skew-symmetric matrices of beam center unit vectors at a given position within the service arc;
- calculating a vector of attitude corrections based on the matrix of beam center pointing errors and the composite matrix of beam center vector skew-symmetric matrices;
- and
- correcting the spacecraft attitude over at least a portion of the service arc by substantially aligning the spacecraft payload frame with a corrected target frame determined based on using the computed attitude corrections.
Dependencies are inferred from the claim text.