Satellites and satellite fleet implementation methods and apparatus

• US 8,511,617 B2
• Filed: 05/22/2009
• Issued: 08/20/2013
• Est. Priority Date: 03/29/2007
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Caplin, Glenn N., Rosen, Harold A., Fowler, Harmon C.
• Primary Examiner(s): Sanderson, Joseph W
• Application Number:
  US12/470,611
• Publication Number:
  US 20090224105A1
• Time in Patent Office: 1,551 Days
• Field of Search: 244/158.1, 244/159.4, 244/159.6, 244/173.1, 244/173.2, 244/173.3, 244/120, 244/158.4
• US Class Current: 244/173.1
• CPC Class Codes: B64G 1/1085 Swarms and constellations
• CPC Class Codes: B64G 1/242 Orbits and trajectories
• CPC Class Codes: B64G 1/2427 Transfer orbits
• CPC Class Codes: B64G 1/26 using jets
• CPC Class Codes: B64G 1/643 for arranging multiple satellites in a single launcher

Abstract

A method for implementing a satellite fleet includes launching a group of satellites within a launch vehicle. In an embodiment, the satellites are structurally connected together through satellite outer load paths. After separation from the launch vehicle, nodal separation between the satellites is established by allowing one or more of the satellites to drift at one or more orbits having apogee altitudes below an operational orbit apogee altitude. A satellite is maintained in an ecliptic normal attitude during its operational life, in an embodiment. The satellite'"'"'s orbit is efficiently maintained by a combination of axial, radial, and canted thrusters, in an embodiment. Satellite embodiments include a payload subsystem, a bus subsystem, an outer load path support structure, antenna assembly orientation mechanisms, an attitude control subsystem adapted to maintain the satellite in the ecliptic normal attitude, and an orbit maintenance/propulsion subsystem adapted to maintain the satellite'"'"'s orbit.

Claims

1. A satellite stack including at least one satellite, the stack comprising:

a first satellite;

a first outer load path support structure positioned on the first satellite, the outer load path support structure comprising a single substantially cylindrical outer load path support structure characterized by an outer radius and having an interior cavity adapted to contain at least one satellite subsystem, the outer load path structure positioned at the outer radius of the first satellite,

a second satellite;

a second outer load path support structure positioned on the second satellite;

and wherein the outer load path support structure of the first satellite is coupled to the second outer load path support structure of the second satellite and to substantially bear a load of the second satellite, when the second satellite is stacked above the first satellite, a contact between the outer load path support structure of the first satellite and the outer load path support structure of the second satellite being substantially continuous along the outer radius of the first outer load path support structure and the second outer load path support structure.

2. The satellite stack of claim 1, further comprising:

one or more solar cell assemblies attached to the outer load path support structure of the first satellite.

3. The satellite stack of claim 1, the first satellite further comprising:

a payload subsystem; and

a bus subsystem coupled to the payload subsystem and to the outer load path support structure, wherein the bus subsystem includes at least one booster rocket and one or more fuel tanks.

4. The satellite stack of claim 3, wherein the outer load path support structure of the first satellite is rigidly coupled to the bus subsystem, and the first satellite further comprises:

a despin control mechanism adapted to couple the bus subsystem to the payload subsystem, wherein the despin control mechanism is further adapted to allow the bus subsystem to spin around a primary axis of the first satellite at a rate wherein the payload subsystem appears substantially stationary, with respect to earth.

5. The satellite stack of claim 1, the first satellite further comprising:

a plurality of axial thrusters, radial thrusters, and canted thrusters adapted to perform satellite orbit maintenance to correct for orbital deviations.

6. The satellite stack of claim 1, wherein the second satellite comprises a booster rocket extending beyond the outer load path support structure of the second satellite, the second satellite stacked on top of the first satellite, and wherein the inner cavity of the first satellite is adapted to receive the booster rocket of the second satellite while the outer load path support structure of the first satellite substantially contacts the outer load path support structure of the second satellite.

7. A stack of satellites comprising:

a first satellite comprising;

a payload subsystem;

a bus subsystem coupled to the payload subsystem;

a first outer structure that substantially surrounds the payload subsystem and the bus subsystem, wherein the outer structure comprises a first outer load path support structure that includes a single substantially cylindrical structure positioned at a single outer radius of the first satellite;

one or more solar array panels attached to the outer structure; and

an attitude control subsystem adapted to maintain the first satellite in an ecliptic normal attitude during an operational life of the first satellite so that the one or more solar array panels are approximately perpendicular to the sun throughout a year, resulting in a thermal boundary that is approximately constant throughout the operational life of the first satellite;

a second satellite comprising a second outer load path support structure comprising a single substantially cylindrical structure positioned at a single outer radius of the second satellite;

wherein the first outer load path support structure is coupled to the second outer load path support structure of the second satellite and substantially bears a load of the second satellite, the second satellite being stacked above the first satellite, a contact between the first outer load path support structure of the first satellite and the second outer load path support structure of the second satellite being substantially continuous along the outer radius of the first outer load path support structure and the outer radius of the second outer load path support structure; and

wherein the second satellite comprises a booster rocket extending below a bottom edge of the second outer load path support structure of the second satellite, the second satellite stacked on top of the first satellite, and wherein the inner cavity of the first satellite is adapted to receive the booster rocket of the second satellite below an upper edge of the first outer load path support structure while the first outer load path support structure of the first satellite substantially contacts the second outer load path support structure of the second satellite.

8. The stack of satellites of claim 7, wherein the attitude control subsystem includes a plurality of axial thrusters, radial thrusters, and canted thrusters.

9. The stack of satellites of claim 7, further comprising:

one or more mechanisms adapted to point an antenna beam produced by the first satellite in a desired direction.

10. The stack of satellites of claim 7, further comprising:

a despin control mechanism adapted to couple the bus subsystem to the payload subsystem, wherein the despin control mechanism is further adapted to allow the bus subsystem to spin around a primary axis of the first satellite at a rate wherein the payload subsystem appears substantially stationary, with respect to earth.

11. The stack of satellites of claim 7, further comprising:

an orbit maintenance subsystem adapted to maintain the first satellite in a Molniya orbit with an orbital period of about 12 hours, an angle of inclination of about 63.4 degrees, and a desired nodal separation of the first satellite, with respect to other satellites within a satellite fleet, of 360 degrees divided by a total number of satellites in the satellite fleet.

12. A stack of satellites, with one satellite having a primary axis and an outer cylinder, the stack of satellites comprising:

a first satellite comprising;

a payload subsystem;

a bus subsystem coupled to the payload subsystem, wherein the bus subsystem includes at least one booster rocket and one or more fuel tanks;

at least one booster rocket adapted to impart impulses substantially parallel to the primary axis;

an orbit maintenance subsystem adapted to correct for orbital deviations during an operational life of the first satellite, wherein the orbit maintenance subsystem includes a plurality of axial thrusters, radial thrusters, and canted thrusters;

a first outer load path support structure that substantially surrounds the payload subsystem, the bus system, and the orbit maintenance system, the first outer load path support structure comprising a substantially cylindrical structure positioned at the outer cylinder of the first satellite;

a second satellite comprising a second outer load path support structure comprising a single substantially cylindrical structure positioned at a single outer radius of the second satellite;

wherein the first outer load path support structure is couple to the second outer load path support structure of the second satellite and substantially bears a load of the second satellite, the second satellite being stacked above the first satellite, a contact between the first outer load path support structure of the first satellite and the second outer load path support structure of the second satellite being substantially continuous along the outer radius of the first outer load path support structure and the outer radius of the second outer load path support structure; and

wherein the second satellite comprises a booster rocket extending below a bottom edge of the second outer load path support structure of the second satellite, the second satellite stacked on top of the first satellite, and wherein the inner cavity of the first satellite is adapted to receive the booster rocket of the second satellite below an upper edge of the first outer load path support structure while the first outer load path support structure of the first satellite substantially contacts the second outer load path support structure of the second satellite.

13. The stack of satellites of claim 12, wherein the axial thrusters are positioned at a bottom of the first satellite between the primary axis and the outer cylinder, wherein the axial thrusters are oriented to impart impulses substantially parallel to the primary axis, and wherein the axial thrusters are adapted to provide a velocity increment in a direction of the primary axis and to re-orient the primary axis.

14. The stack of satellites of claim 12, wherein the radial thrusters are positioned around the outer cylinder, wherein the radial thrusters are oriented to impart impulses that are substantially perpendicular to the primary axis, and wherein the radial thrusters are adapted to increase and decrease a rate of spin around the primary axis and to provide a velocity increment in a direction perpendicular to the primary axis.

15. The stack of satellites of claim 12, wherein the canted thrusters are positioned around an outer surface of the first satellite, wherein the canted thrusters are oriented to impart impulses that substantially intersect a center of gravity of the first satellite, and wherein the canted thrusters are adapted to provide a velocity increment in the direction of the canted thruster.

16. The stack of satellites of claim 15, wherein a first set of the canted thrusters are positioned above a plane that bisects the center of gravity and is perpendicular to the primary axis, and wherein a second set of the canted thrusters are positioned below the plane.

17. The stack of satellites of claim 16, wherein a cant angle between impulse vectors of the first set and the plane is in a range of about 30 degrees to about 60 degrees.

18. The stack of satellites of claim 16, wherein a cant angle between impulse vectors of the second set and the plane is in a range of about 30 degrees to about 60 degrees.

19. The stack of satellites of claim 12, wherein the attitude control subsystem is further adapted to maintain the first satellite in an ecliptic normal attitude.

20. The stack of satellites of claim 12, wherein the orbit maintenance subsystem is further adapted to maintain the first satellite in a Molniya orbit with an orbital period of about 12 hours, an angle of inclination of about 63.4 degrees, and a desired nodal separation of the first satellite, with respect to other satellites within a satellite fleet, of 360 degrees divided by a total number of satellites in the satellite fleet.

21. A stack of satellites comprising:

a first satellite comprising;

a payload subsystem, which includes a downlink antenna adapted to produce an antenna pattern that is a figure of revolution;

a bus subsystem coupled to the payload subsystem, wherein the bus subsystem includes at least one booster rocket and one or more fuel tanks;

a first outer load path support structure coupled to the bus subsystem, wherein the first outer load path support structure substantially surrounds the payload subsystem and the bus subsystem, wherein the first outer load path support structure includes a substantially cylindrical structure positioned at an outer radius of the first satellite;

at least one booster rocket adapted to impart impulses substantially parallel to the primary axis;

an attitude control subsystem adapted to maintain the first satellite in an ecliptic normal attitude during an operational life of the satellite;

an orbit maintenance subsystem to correct for orbital deviations during an operational life of the first satellite, wherein the attitude control subsystem and the orbit maintenance subsystem includes a plurality of axial thrusters, radial thrusters, and canted thrusters; and

a second satellite comprising a second outer load path support structure comprising a single substantially cylindrical structure positioned at a single outer radius of the second satellite; and

wherein the first outer load path support structure is configured to couple to the second outer load path support structure of the second satellite and to substantially bear a load of the second satellite, the second satellite being stacked above the first satellite, a contact between the first outer load path support structure of the first satellite and the second outer load path support structure of the second satellite being substantially continuous along the outer radius of the first outer load path support structure and the outer radius of the second outer load path support structure.