Momentum unloading using gimbaled thrusters
OwnerKeith F. Keitel, Richard A. Noyola +3inventors
InventorsKeith F. Keitel, Richard A. Noyola, John F. Yocum, Jr., David K. Abernethy, Bernard M. Anzel
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Abstract
A method of simultaneously controlling East/West and North/South positioning and unloading momentum of a spacecraft while orbiting an object. The spacecraft has a thruster array and a momentum accumulator. The method entails moving said spacecraft towards a node of the orbit. At a predetermined position on the orbit, separate from the node, a thruster of the thruster array is fired so as to control the orbital position of the spacecraft. While the thruster is being fired, momentum is dumped from the momentum accumulator at the predetermined position so that any loss in control in the attitude of the spacecraft is reduced.
Claims21
A method of simultaneously controlling East/West and North/South positioning and unloading momentum of a spacecraft while orbiting the Earth, said spacecraft having a thruster array, an on-board processor capable of receiving stationkeeping commands from a ground station located on the Earth that correspond to desired spacecraft velocity changes and capable of calculating thruster firing parameters necessary to meet both stationkeeping and momentum dumping requirements of said spacecraft, and a momentum accumulator, said method comprising the steps of:
- receiving desired spacecraft velocity changes from said ground station;
- moving said spacecraft towards a node of said orbit;
- calculating, solely using said on-board processor, thruster firing parameters necessary to meet said stationkeeping requirements and momentum dumping requirements;
- firing a thruster of said thruster array at a predetermined position on said orbit, separate from said node, so as to control the orbital position of said spacecraft, wherein said predetermined position is calculated by said on-board processor;
- and
- simultaneously dumping momentum from said momentum accumulator at said predetermined position and while said thruster is being fired so that any loss in control in the attitude of said spacecraft is reduced.
A method of simultaneously controlling East/West and North/South positioning and unloading momentum of a spacecraft while orbiting the Earth, said spacecraft having first, second, third and fourth thrusters, an on-board processor capable of receiving stationkeeping commands from a ground station located on the Earth that correspond to desired spacecraft velocity changes and capable of calculating thruster firing parameters necessary to meet both stationkeeping and momentum dumping requirements of said spacecraft, and a momentum accumulator, said method comprising the steps of:
- moving said spacecraft towards a node of said orbit;
- calculating, solely using said on-board processor, thruster firing parameters necessary to meet said stationkeeping requirements and momentum dumping requirements;
- firing said first thruster at a predetermined position on said orbit, separate from said node, so as to control the orbital position of said spacecraft, wherein said predetermined position is calculated by said on-board processor;
- and
- simultaneously dumping momentum from said momentum accumulator at said predetermined position and while said first thruster is being fired so that any loss in control in the attitude of said spacecraft is reduced.
A method of simultaneously controlling East/West and North/South positioning and unloading momentum from a momentum accumulator on a spacecraft, said spacecraft including an on-board processor capable of receiving stationkeeping commands from a ground station located on the Earth that correspond to desired spacecraft velocity changes and capable of calculating thruster firing parameters necessary to meet both stationkeeping and momentum dumping requirements of said spacecraft, a first momentum dumper and a second momentum dumper, said method comprising the steps of:
- monitoring the amount of momentum stored by said momentum accumulator;
- calculating thruster firing parameters necessary to meet both stationkeeping and momentum dumping requirements of said spacecraft solely by utilizing said on-board processor;
- and
- activating one or both of said first and second momentum dumpers to simultaneously dump momentum from said momentum accumulator in response to the momentum dumping requirement calculated by said on-board processor.
Dependencies are inferred from the claim text.