AFT deployable thermal radiators for spacecraft

[0002] Priority is herewith claimed under 35 U.S.C. §119(e) from copending Provisional Patent Application 60/061,672, filed Oct. 10, 1997, entitled “Aft Deployable Thermal Radiators for Spacecraft”, by Randy Pon. The disclosure of this Provisional Patent Application is incorporated by reference herein in its entirety.

[0003] This invention relates generally to spacecraft and, in particular, to those spacecraft employing thermal radiator panels for removing heat from the spacecraft.

[0004] It is known in the art to provide thermal radiators that are deployed off of the East/West sides of a spacecraft. Such panels are useful in removing heat from the spacecraft and radiating the heat into space. However, this conventional approach has a number of disadvantages. For example, the deployed radiation panels are not optimally positioned with respect to North/South mounted radiator panels. Further by example, the deployable radiator panels may have dimensional restrictions caused by field of view (FOV) requirements of East/West antenna reflectors and/or other spacecraft structures.

[0005] It is thus a first object and advantage of this invention to provide at least one thermal radiator panel that is deployable at the aft end of a spacecraft along, or at an angle to, a longitudinal or Z-axis of the spacecraft.

[0006] It is a further object and advantage of this invention to provide a plurality of aft-mounted thermal radiator panels that are canted when deployed with respect to a transverse edge of a spacecraft bus, thereby minimizing plume impingement from a centrally located thruster and also minimizing a chance of collision with other spacecraft structures, such as deployed solar array panels.

[0007] The foregoing and other problems are overcome and the objects of the invention are realized by methods and apparatus in accordance with embodiments of this invention.

[0008] In accordance with this invention a spacecraft comprises at least one thermal radiator panel that is moveable from a stowed position to a deployed position, said deployed position being off of an aft end of the spacecraft.

[0009] Further in accordance with this invention a spacecraft comprises at least one thermal radiator panel that is moveable from a stowed position to a deployed position, said deployed position being off of an aft end of the spacecraft, wherein in said deployed position a longitudinal axis of said panel forms a non-zero angle with a longitudinal axis (taken to be the Z-axis) of said spacecraft.

[0010] Further in accordance with this invention a spacecraft comprises at least one thermal radiator panel that is moveable from a stowed position to a deployed position, said deployed position being off of an aft end of the spacecraft, wherein in said deployed position a longitudinal axis of said panel intersects a Z-axis of said spacecraft.

[0011] Further in accordance with this invention a spacecraft comprises at least one thermal radiator panel that is moveable from a stowed position to a deployed position, said deployed position being off of an aft end of the spacecraft, wherein in said deployed position a transverse edge of said panel is non-parallel to a transverse aft edge of said spacecraft.

[0012] In a presently preferred embodiment of this invention a spacecraft includes at least four thermal radiator panels arranged as pairs of thermal radiator panels. A first pair of the panels is initially stowed along a North facing surface of the spacecraft and a second pair of the panels is initially stowed along a South facing surface of the spacecraft. Each of the at least four panels is coupled to a hinge mechanism at an anti-Earth facing end of the spacecraft and is rotatable by the hinge mechanism from a stowed position to a deployed position. The deployed position is a position that is off of the anti-Earth facing end of the spacecraft.

[0013] In the presently preferred embodiment of this invention, when in the deployed position a longitudinal axis of each of the at least four panels forms a non-zero angle with an Earth pointing axis of said spacecraft.

[0014] The above set forth and other features of the invention are made more apparent in the ensuing Detailed Description of the Invention when read in conjunction with the attached Drawings, wherein:

[0015] FIG. 1 is a view along a Y-axis of a spacecraft, showing a pair of deployable thermal radiator panels in a stowed position;

[0016] FIG. 2 is an isometric view of the spacecraft showing the pair of deployable thermal radiator panels in the stowed position;

[0017] FIG. 3 is view along the Y-axis of a spacecraft, showing the pair of deployable thermal radiator panels in a fully deployed position;

[0018] FIG. 4 is an isometric view of the spacecraft showing the pair of deployable thermal radiator panels in the deployed position; and

[0019] FIG. 5 is a view of the spacecraft along the X-axis showing one pair of the solar radiator panels in the deployed position and one pair in the stowed position.

[0020] Reference is made to FIGS. 1-5 for illustrating an exemplary embodiment of a spacecraft 10 having aft deployable thermal radiator panels 18 in accordance with this invention. The spacecraft 10 includes a spacecraft bus 12, solar array panels 14, an aft mounted thruster 16, the aft deployable thermal radiator panels 18, and thermal radiator panel hinge mechanisms 20. FIGS. 1 and 2 show the deployable thermal radiator panels 18 stowed against satellite North and South radiator panels 22. The hinge mechanisms 20 are located at the aft end of the satellite 10 along a transverse edge of the satellite bus 12. The satellite 10 includes a mechanism, such as a releasable clamp 24, for holding the thermal radiator panels 18 in the stowed position. When the holding mechanism is released after launch, each thermal radiator panel 18 is enabled to rotate about an axis that passes through its respective hinge mechanism 20 to assume a fully deployed position. This rotation is depicted by the arrow A in FIG. 5. As seen best if FIGS. 3 and 4, when in the deployed position, the thermal radiation panels 28 stand-off aft, or in an anti-Earth direction from the aft end of the spacecraft 10. The hinge mechanisms 20 may include a spring tension mechanism for rotating the thermal radiator panels 18, or any other mechanism that is suitable for rotating the thermal radiator panels from the stowed to the deployed position.

[0021] When deployed, heat is transported from the satellite 10 to the aft deployed thermal radiator panels 18 via any suitable flexible heat transfer device, including loop heat pipes, capillary pump loops, and flexible heat pipes. The heat transfer device may be externally or internally connected the satellite's heat pipe network, or any discrete heat source within the satellite 10.

[0022] Exemplary dimensions for one of the deployable thermal radiator panels 18 are 50 inches by 100 inches. An exemplary thickness is in a range of 0.5 to 1 inch. The panels 18 can be constructed of any suitable material that is known for use fabricating thermal radiator panels, including honeycomb constructions. Each deployable thermal radiator panel 18 may have an optical solar reflector (OSR) on one or both sides. The panels 18 are preferably locked in position when deployed off of the aft end (also referred to herein as the anti-Earth pointing end) of the spacecraft 10. Although four panels 18 are shown (two pairs of panels), more or less than this number could be used.

[0023] Further in accordance with this invention the hinge mechanisms 20 are constructed such that the thermal radiator panels 18 are offset at an angle θ from the satellite's Z-axis (see FIG. 3) when fully deployed. One suitable angle is in a range of about 30 degrees to about 40 degrees, although other angles may be used if desired.

[0024] As seen best in FIGS. 1 and 3, the hinge mechanisms 20 are mounted on the satellite such that the axis of rotation of each hinge mechanisms 20 is angled at an α relative to the Z-axis of the satellite 10. Each hinge mechanism 20 includes bent support members 30 connecting the corresponding thermal radiator panels 18 to the hinge mechanism. The bent support members 30 are bent to offset the angle α of the hinge mechanisms 20 so that when the radiator panels 18 are stowed, the longitudinal axis of each panel 18 is generally parallel with the Z-axis of the satellite 10. The angle θ between the longitudinal axis of each panel 18 in the deployed position and the Z-axis of the satellite 10 (see FIG. 3) is a generally complementary angle to the angle α between the axis of rotation of each hinge and the Z-axis of the satellite 10.

[0025] The aft deployment of the thermal radiator panels 18 in accordance with this invention allows a full 180° rotation to enable the radiator panels 18 to be parallel with the North/South radiator panels 22, thereby producing superior thermal performance.

[0026] The aft deployment further eliminates dimensional restrictions caused by East/West antenna reflector (not shown) field of view requirements.

[0027] The use of the canted angle at the final deployed position also minimizes plume impingement from the centrally located thruster 16 on the aft end of satellite 10.

[0028] Furthermore, the use of the canted angle at deployment also allows the radiator panels 18 to swing away from the deployed solar array panels 14, thus minimizing the chance of a collision during deployment.

[0029] Although the deployed radiator panels 18 are shown in FIGS. 4 and 5 as being essentially coplanar with the spacecraft bus 12 North and South surfaces, in particular the North and South radiator panels 22, it is within the scope of the teaching of this invention to provide the hinge mechanisms such that the deployed radiator panels are parallel with, but offset from (either above or below), the North and South surfaces of the spacecraft bus 12.

[0030] Thus, while the invention has been particularly shown and described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that changes in form and details may be made therein without departing from the scope and spirit of the invention.