Thruster orbit control method and configuration

Patent metadata

Field	Value
Publication number	US-9296494-B1
Application number	US-201213572586-A
Country	US
Kind code	B1
Filing date	Aug 10, 2012
Priority date	Aug 10, 2012
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

Embodiments of the present invention provide an ion-thruster stationkeeping method and mounting configuration that reduces the propellant penalty when a single thruster fails, e.g., in the case where only three of a spacecraft's four ion thrusters are available. By improving firing efficiency for the single-thruster failure case, on-board propellant is reduced, thereby allowing increased payload mass. Also, the configuration supports both N/S and E/W stationkeeping using four ion thrusters (or three thrusters for the failure case) and therefore does not require a separate propulsion system or thrusters for E/W stationkeeping.

First claim

What is claimed is:

1. A spacecraft, comprising:
a spacecraft body having an X-axis, a Y-axis, and a Z-axis;
a plurality of gimbaled platforms mounted on an aft end of the spacecraft body; and
a plurality of thrusters mounted on the plurality of gimbaled platforms;
wherein each of the plurality of thrusters is oriented at an angle α, wherein α is an angle between the X-axis and a projection of a thrust vector of the respective thruster in an X/Y plane of the spacecraft;
wherein each of the plurality of thrusters is orientated at an angle θ, where θ is an angle of the thrust vector of the respective thruster from plus or minus Z-axis;
wherein the plurality of thrusters are configured to be located outside of the aft end of the spacecraft body along the Z-axis during operation; and
wherein angle α and angle θ substantially maximize the following expression:

ISP
eff

=

1

F

E
/
W

ISP

E
/
W

⁢
sin
⁢

⁢
θsinα

+

F

N
/
S

ISP

N
/
S

⁢
cos
⁢

⁢
θcosϕ

where F E/W is an E/W stationkeeping fraction of total stationkeeping Delta-V, F N/S is an N/S stationkeeping fraction of the total stationkeeping Delta-V, ISP E/W is an ISP for E/W stationkeeping, ISP N/S is an ISP for N/S stationkeeping, and φ=tan −1 (2 tan α).

2. The spacecraft of claim 1 , wherein the plurality of thrusters comprise ion thrusters.

3. The spacecraft of claim 2 , wherein the plurality of thrusters comprise Hall Current Thrusters (HCTs).

4. The spacecraft of claim 1 , wherein the plurality of thrust vector of each of the thrusters passes through a center of mass of the spacecraft.

5. The spacecraft of claim 1 , wherein the plurality of thrusters comprise two pairs of thrusters, and Y and Z thruster components for the thrusters in each pair have opposite signs.

6. The spacecraft of claim 1 , wherein one or more of the plurality of thrusters are configured to be oriented in response to a single-thruster failure.

7. The spacecraft of claim 1 , wherein one or more of the plurality of thrusters are set to be fired at an offset from an ascending node or a descending node.

8. A spacecraft, comprising:
a spacecraft body having an X-axis, a Y-axis, and a Z-axis;
a plurality of gimbaled platforms coupled to the spacecraft body; and
a plurality of thrusters mounted on the plurality of gimbaled platforms;
wherein each of the plurality of thrusters is oriented at an angle α, wherein α is an angle between the X-axis and a projection of a thrust vector of the respective thruster in an X/Y plane of the spacecraft, and α is within a range of 10 to 15 degrees;
wherein each of the plurality of thrusters is orientated at an angle θ, where θ is an angle of the thrust vector of the respective thruster from plus or minus Z-axis, and θ is within a range of 35 to 50 degrees;
wherein the plurality of thrusters are configured to be located outside of the aft end of the spacecraft body along the Z-axis during operation; and
wherein the angle α or the angle θ is based on at least one of an E/W stationkeeping fraction of total stationkeeping Delta-V, an N/S stationkeeping fraction of the total stationkeeping Delta-V, an ISP for E/W stationkeeping, and an ISP for N/S stationkeeping.

9. The spacecraft of claim 8 , wherein the plurality of thrusters comprise ion thrusters.

10. The spacecraft of claim 8 , wherein the thrust vector of each of the plurality of thrusters passes through a center of mass of the spacecraft.

11. The spacecraft of claim 8 , wherein the plurality of thrusters comprise two pairs of thrusters, and Y and Z thruster components for the thrusters in each pair have opposite signs.

12. The spacecraft of claim 8 , wherein one or more of the plurality of thrusters are configured to be oriented in response to a single-thruster failure.

13. The spacecraft of claim 8 , wherein one or more of the plurality of thrusters are set to be fired at an orbit position offset from an ascending node or a descending node by 20 to 28 degrees.

Assignees

• Campbell Brian D
• Goodzeit Neil E
• Lockheed Corp

Inventors

• Campbell Brian D
• Goodzeit Neil E

Classifications

• B64G1/413 Primary

  Ion or plasma engines · CPC title

• B64G1/2429

  Station keeping · CPC title

• B64G1/262 Primary

  having adjustable angles, e.g. gimbaled thrusters · CPC title

• B64G1/26

  using jets · CPC title

• B64G1/405

  Operations & Transport · mapped topic