Satellites and Satellite Fleet Implementation Methods and Apparatus

• US 20090224105A1
• Filed: 05/22/2009
• Published: 09/10/2009
• 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.
• Granted Patent: US 8,511,617 B2
• Time in Patent Office: Days
• US Class Current: 244/158.400
• CPC Class Codes: B64G 1/1085 Swarms and constellations
• CPC Class Codes: B64G 1/242 Orbits and trajectories
• 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

1-14. -14. (canceled)

15. A satellite comprising:

an outer load path support structure, which includes a substantially cylindrical structure having an interior cavity adapted to contain at least one satellite subsystem.

16. The satellite of claim 15, and wherein the outer load path support structure is further adapted to couple to a second outer load path support structure of a second satellite and to bear a load of the second satellite, when the second satellite is stacked above the satellite.

17. The satellite of claim 15, further comprising:

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

18. The satellite of claim 15, 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.

19. The satellite of claim 18, wherein the outer load path support structure is rigidly coupled to the bus subsystem, and the 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 satellite at a rate wherein the payload subsystem appears substantially stationary, with respect to earth.

20. The satellite of claim 15, further comprising:

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

21. A satellite comprising:

a payload subsystem;

a bus subsystem coupled to the payload subsystem;

an outer structure that substantially surrounds the payload subsystem and the bus subsystem;

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

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

22. The satellite of claim 21, wherein the attitude control subsystem includes a plurality of axial thrusters, radial thrusters, and canted thrusters.

23. The satellite of claim 21, further comprising:

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

24. The satellite of claim 21, 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 satellite at a rate wherein the payload subsystem appears substantially stationary, with respect to earth.

25. The satellite of claim 21, wherein the outer structure comprises:

an outer load path support structure that includes a substantially cylindrical structure.

26. The satellite of claim 21, further comprising:

an orbit maintenance subsystem adapted to maintain the 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 satellite, with respect to other satellites within a satellite fleet, of 360 degrees divided by a total number of satellites in the satellite fleet.

27. A satellite having a primary axis and an outer cylinder, the 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; and

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

28. The satellite of claim 27, wherein the axial thrusters are positioned at a bottom of the 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.

29. The satellite of claim 27, 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.

30. The satellite of claim 27, wherein the canted thrusters are positioned around an outer surface of the satellite, wherein the canted thrusters are oriented to impart impulses that substantially intersect a center of gravity of the satellite, and wherein the canted thrusters are adapted to provide a velocity increment in the direction of the canted thruster.

31. The satellite of claim 30, 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.

32. The satellite of claim 31, 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.

33. The satellite of claim 31, 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.

36. The satellite of claim 27, wherein the attitude control subsystem is further adapted to maintain the satellite in an ecliptic normal attitude.

37. The satellite of claim 27, wherein the orbit maintenance subsystem is further adapted to maintain the 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 satellite, with respect to other satellites within a satellite fleet, of 360 degrees divided by a total number of satellites in the satellite fleet.

38. A 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;

an outer load path support structure coupled to the bus subsystem, wherein the outer load path support structure substantially surrounds the payload subsystem and the bus subsystem, wherein the outer load path support structure includes a substantially cylindrical structure, and wherein the outer load path support structure is adapted to couple to a second outer load path of a second satellite and to bear a load of a second satellite stacked above the satellite;

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

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

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