Method using double thruster firings to deadbeat flexible solar array structural oscillations
AssigneeSpace Systems/Loral, Inc.
InventorsTung Y Liu, Kam K Chan
Life of this patent
Estimating the term…
Abstract
A spacecraft includes a plurality of thrusters mounted at predetermined locations on a spacecraft structure, individual ones the plurality of thrusters being fired for generating a torque about a desired axis. The firing of a thruster is partitioned into two firings that are offset in time by an amount .DELTA.t, wherein .DELTA.t=(1/2).times.(1/F).times.SF, where F is a dominant modal frequency, in Hertz, for any particular axis (nominally the 1st mode) of the spacecraft structure, and where SF is a scale factor that is adjustable about the frequency. In a presently preferred embodiment the thruster is a low thrust thruster that is mounted on a solar array panel, and the thrusters are fired in pairs.
Claims9
A spacecraft comprising a plurality of low thrust thrusters mounted at predetermined locations on a spacecraft structure, said plurality of low thrust thrusters being fired in pairs for generating a desired torque, where the firing of a low thrust thruster pair is partitioned into two firings that are offset in time by an amount .DELTA.t, wherein
- .DELTA.t=(1/2).times.(1/F).times.SF,
- where F is a dominant modal frequency, in Hertz, for any particular axis (nominally the 1st mode) of the spacecraft structure, and where SF is a scale factor that is adjustable about the frequency.
A geosynchronous spacecraft comprising a first set of four low thrust thrusters and a second set of four, redundant, low thrust thrusters, said first and second sets of low thrust thrusters being mounted in a predetermined configuration on a spacecraft structure, said plurality of low thrust thrusters being fired in pairs for generating a desired torque, where the firing of a low thrust thruster pair is partitioned into two firings that are offset in time by an amount .DELTA.t, wherein
- .DELTA.t=(1/2).times.(1/F).times.SF,
- where F is a dominant modal frequency, in Hertz, for any particular axis (nominally the 1st mode) of the spacecraft structure, and where SF is a scale factor that is adjustable about the frequency.
A spacecraft comprising a plurality of thrusters mounted at predetermined locations on a spacecraft structure, individual ones said plurality of thrusters being fired for generating a torque about a desired axis, where the firing of a thruster is partitioned into two firings that are offset in time by an amount .DELTA.t, wherein
- .DELTA.t=(1/2).times.(1/F).times.SF,
- where F is a dominant modal frequency, in Hertz, for any particular axis (nominally the 1st mode) of the spacecraft structure, and where SF is a scale factor that is adjustable about the frequency.
A method for operating a spacecraft, comprising steps of:
- providing a plurality of low thrust thrusters mounted at predetermined locations on a spacecraft structure;
- controllably firing said plurality of low thrust thrusters in pairs for generating a desired torque;
- and
- partitioning the firing of a low thrust thruster pair into two firings that are offset in time by an amount .DELTA.t, wherein
- .DELTA.t=(1/2).times.(1/F).times.SF,
- where F is a dominant modal frequency, in Hertz, for any particular axis (nominally the 1st mode) of the spacecraft structure, and where SF is a scale factor that is adjustable about the frequency.
Dependencies are inferred from the claim text.