Method for acquiring three-axis earth pointing attitude for an initially spinning spacecraft

Claim 1

A method for acquiring a 3-axis Earth pointing attitude for an initially spinning spacecraft, which spacecraft includes means for providing three-axis spacecraft angular rate information and sun sensing means, and torquing means, comprising the steps of: generating 3-axis angular rate information from said means for providing three-axis angular rate information; determining the attitude of the spin axis of said spinning spacecraft relative to the sun to produce axis orientation information; generating a sun pulse from said sun sensing means at an instant during the spin cycle of said spinning spacecraft to produce additional orientation information which, together with said axis orientation information, completely determines the 3-axis attitude of said spacecraft; beginning at the time of said sun pulse, calculating the 3-axis instantaneous attitude of said spacecraft by updating said attitude of said spin axis and said additional orientation information with said angular rate information.

Claim 2

A method for acquiring a 3-axis Earth pointing attitude for an initially spinning spacecraft, which spacecraft includes means for providing three-axis spacecraft angular rate information and sun sensing means, and torquing means, comprising the steps of: generating 3-axis angular rate information from said means for providing three-axis angular rate information; determining the attitude of the spin axis of said spinning spacecraft relative to the sun to produce axis orientation information; generating a sun pulse from said sun sensing means at an instant during the spin cycle of said spinning spacecraft to produce additional orientation information which, together with said axis orientation information, completely determines the 3-axis attitude of said spacecraft; beginning at the time of said sun pulse, calculating the 3-axis instantaneous attitude of said spacecraft by updating said attitude of said spin axis and said additional orientation information with said angular rate information.

Claim 8

A method for acquiring a 3-axis Earth pointing attitude for an initially spinning spacecraft, which spacecraft includes sun sensing means, torquing means, and means for providing three-axis angular rate information, comprising the steps of: generating a 3-axis angular rate information from said means for providing three-axis angular rate information; determining the attitude of the spin axis of said spinning spacecraft relative to the sun to produce axis orientation information; generating a sun pulse from said sun sensing means at an instant during the spin cycle of said spinning spacecraft to produce additional orientation information which, together with said axis orientation information, completely determines the 3-axis attitude of said spacecraft; beginning at the time of said sun pulse, calculating the instantaneous attitude of said spacecraft by propagating quaternions to update said axis and additional orientation information with said angular rate information.

Claim 9

A method for acquiring a 3-axis Earth pointing attitude for an initially spinning spacecraft, which spacecraft includes sun sensing means, torquing means, and means for providing three-axis angular rate information, comprising the steps of: generating a 3-axis angular rate information from said means for providing three-axis angular rate information; determining the attitude of the spin axis of said spinning spacecraft relative to the sun to produce axis orientation information; generating a sun pulse from said sun sensing means at an instant during the spin cycle of said spinning spacecraft to produce additional orientation information which, together with said axis orientation information, completely determines the 3-axis attitude of said spacecraft; beginning at the time of said sun pulse, calculating the instantaneous attitude of said spacecraft by propagating quaternions to update said axis and additional orientation information with said angular rate information.

Claim 13

A method for acquiring a 3-axis Earth pointing attitude for an initially spinning spacecraft, which spacecraft includes sun sensing means, torquing means, and means for providing three-axis angular rate information, comprising the steps of: generating a 3-axis angular rate information from said means for providing three-axis angular rate information; determining the attitude of the spin axis of said spinning spacecraft relative to the sun to produce axis orientation information; generating a sun pulse from said sun sensing means at an instant during the spin cycle of said spinning spacecraft to produce additional orientation information which, together with said axis orientation information, completely determines the 3-axis attitude of said spacecraft; beginning at the time of said sun pulse, calculating the instantaneous attitude of said spacecraft by updating said axis and additional orientation information with said angular rate information; closing a feedback loop including a torquing means and fed with said instantaneous attitude and rate for tending to reduce said spin and for orienting said spacecraft in a particular attitude relative to the Earth; after said closing step, rotating an angular momentum storage body while maintaining said feedback loop closed to maintain said particular attitude about at least one axis; and further comprising the step of opening said feedback loop after said momentum storage body has reached an operating speed.

Claim 14

A method for acquiring a 3-axis Earth pointing attitude for an initially spinning spacecraft, which spacecraft includes sun sensing means, torquing means, and means for providing three-axis angular rate information, comprising the steps of: generating a 3-axis angular rate information from said means for providing three-axis angular rate information; determining the attitude of the spin axis of said spinning spacecraft relative to the sun to produce axis orientation information; generating a sun pulse from said sun sensing means at an instant during the spin cycle of said spinning spacecraft to produce additional orientation information which, together with said axis orientation information, completely determines the 3-axis attitude of said spacecraft; beginning at the time of said sun pulse, calculating the instantaneous attitude of said spacecraft by updating said axis and additional orientation information with said angular rate information; closing a feedback loop including a torquing means and fed with said instantaneous attitude and rate for tending to reduce said spin and for orienting said spacecraft in a particular attitude relative to the Earth; after said closing step, rotating an angular momentum storage body while maintaining said feedback loop closed to maintain said particular attitude about at least one axis; and further comprising the step of opening said feedback loop after said momentum storage body has reached an operating speed.

Claim 17

A method for launching a spacecraft into a predetermined orbit in a 3-axis stabilized attitude, comprising the steps of: loading a spacecraft into an Earth-to-space shuttle, said spacecraft including sun sensing means, torquing means, and 3-axis spacecraft angular rate determining means; transporting said shuttle into a low Earth orbit; unloading said spacecraft from said shuttle and spin-stabilizing said spacecraft; applying thrust to said spacecraft for moving said spacecraft from said low Earth orbit to an elliptical transition orbit including an apogee near the attitude of said predetermined orbit; determining the orientation of the spin axis of said spin-stabilized spacecraft; producing a sun pulse from said sun sensing means at a particular instant during the spin cycle of said spacecraft, to thereby identify a particular known attitude; continuously updating said known attitude by the use of said 3-axis angular rate information to produced a stream of attitude information; and closing a feedback loop including said torquing means for reducing said spin and for causing said spacecraft to adopt a predetermined attitude.

Claim 18

A method for launching a spacecraft into a predetermined orbit in a 3-axis stabilized attitude, comprising the steps of: loading a spacecraft into an Earth-to-space shuttle, said spacecraft including sun sensing means, torquing means, and 3-axis spacecraft angular rate determining means; transporting said shuttle into a low Earth orbit; unloading said spacecraft from said shuttle and spin-stabilizing said spacecraft; applying thrust to said spacecraft for moving said spacecraft from said low Earth orbit to an elliptical transition orbit including an apogee near the attitude of said predetermined orbit; determining the orientation of the spin axis of said spin-stabilized spacecraft; producing a sun pulse from said sun sensing means at a particular instant during the spin cycle of said spacecraft, to thereby identify a particular known attitude; continuously updating said known attitude by the use of said 3-axis angular rate information to produced a stream of attitude information; and closing a feedback loop including said torquing means for reducing said spin and for causing said spacecraft to adopt a predetermined attitude.

Claim 20

A method for launching a spacecraft into a predetermined orbit in a 3-axis stabilized attitude, comprising the steps of: loading a spacecraft onto an unmanned vehicle, said spacecraft including sun sensing means, Earth sensing means, torquing means, and 3-axis spacecraft angular rate determining means; operating said vehicle to cause it to assume an elliptical orbit including an apogee near the altitude of said predetermined orbit; releasing said spacecraft from said vehicle and spin-stabilizing said spacecraft; determining the orientation of the spin axis of said spin-stabilized spacecraft; producing a sun pulse from said sun sensing means at a particular instant during the spin cycle of said spacecraft, to thereby indicate a particular known attitude; continuously updating said known attitude by use of said 3-axis spacecraft angular rate to produce a stream of attitude information; and closing a feedback loop including said torquing means for reducing said spin and for causing said spacecraft to adopt a predetermined attitude.

Claim 21

A method for launching a spacecraft into a predetermined orbit in a 3-axis stabilized attitude, comprising the steps of: loading a spacecraft onto an unmanned vehicle, said spacecraft including sun sensing means, Earth sensing means, torquing means, and 3-axis spacecraft angular rate determining means; operating said vehicle to cause it to assume an elliptical orbit including an apogee near the altitude of said predetermined orbit; releasing said spacecraft from said vehicle and spin-stabilizing said spacecraft; determining the orientation of the spin axis of said spin-stabilized spacecraft; producing a sun pulse from said sun sensing means at a particular instant during the spin cycle of said spacecraft, to thereby indicate a particular known attitude; continuously updating said known attitude by use of said 3-axis spacecraft angular rate to produce a stream of attitude information; and closing a feedback loop including said torquing means for reducing said spin and for causing said spacecraft to adopt a predetermined attitude.