Aeronautics and astronautics – Spacecraft – Spacecraft formation – orbit – or interplanetary path
Patent
1997-08-27
1998-12-29
Barefoot, Galen L.
Aeronautics and astronautics
Spacecraft
Spacecraft formation, orbit, or interplanetary path
244138R, 244160, 102386, B64G 158
Patent
active
058531513
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a braking shield for a spacecraft, and more precisely, but not exclusively, a shield that is designed to slow down an earth observation satellite by friction with the layers of the atmosphere at low altitude (typically 120 km to 140 km).
To put a satellite into low orbit, it is possible to use a specially adapted launcher.
Nevertheless, it is sometimes economically more advantageous to take advantage, whenever possible, of space that remains available in the nosecone of a standard launcher adapted to put a payload into high orbit, and then to actuate propulsion means with which the satellite is fitted to send it into low orbit.
To reduce the quantity of propellant on board the satellite, proposals have been made to place a braking drag at the back of the satellite for the purpose of slowing down the satellite by friction with the low altitude layers of the atmosphere and consequently of reducing the apogee altitude of the satellite's orbit. The satellite propulsion means are then no longer actuated for performing braking directly, but for the purpose of sending the satellite into the low altitude layers of the atmosphere where it loses energy by friction and then, after braking, to cause it to leave those layers of the atmosphere in order to reach its final orbit.
The braking drag is placed at the back of the satellite so as to impart a stable attitude to the satellite, i.e. an angle of incidence that is constant relative to the flow of gas striking it.
Braking shields are also known for atmospheric re-entry of craft that have gone beyond the atmosphere, with such shields being in the form of nosecone-shaped shells (to impart a stable attitude to the spacecraft) placed at the front thereof, and also providing heat protection to the spacecraft fitted therewith by deflecting the flow of gases.
It is desirable to fit satellites with shields that are placed in front so as to combine the functions of providing both braking and heat protection. Nevertheless, because such shields are nosecone-shaped, they sometimes take up more room in a longitudinal direction than is compatible with the space available in the nosecone of the launcher, particularly when advantage is being taken of some other satellite being put into a high orbit by a standard launcher, as mentioned above.
The present invention seeks to propose a novel braking shield for a spacecraft, in particular an observation satellite, the shield being of size compatible with the space available under the nosecone of a launcher, and serving to provide the spacecraft simultaneously with attitude stability and with heat protection.
The shield of the invention is characterized in that it includes at least one gap shaped in such a manner as to provide a through section to the flow of gas striking the spacecraft, which section increases with increasing angle of incidence of the spacecraft, for the purpose of creating an aerodynamic force couple tending to return the spacecraft towards a position of lower incidence.
Thus, the invention serves to stabilize the attitude of the satellite in passive manner, without it being necessary to adopt a nosecone-shaped shell.
In a preferred embodiment of the invention, the shield comprises a succession of walls having axial symmetry about the longitudinal axis of the spacecraft, said walls being coaxial and leaving between them at least one annular opening of through section offered to the flow that increases with increasing angle of incidence of the spacecraft. Preferably, the shield includes a succession of truncated cones disposed coaxially so as to appear as a solid surface in front view at zero incidence, and, at non-zero incidence, to appear as a surface having gaps creating an aerodynamic couple tending to return the spacecraft towards a position of zero incidence.
The present invention also provides a satellite fitted with a shield as specified above.
Other characteristics and advantages of the present invention appear on reading the following detailed description of a non-limiting embod
REFERENCES:
patent: 3098630 (1963-07-01), Cinnors
patent: 3405887 (1968-10-01), Mixson
patent: 3604667 (1971-09-01), Moraes
patent: 5080306 (1992-01-01), Porter et al.
patent: 5108046 (1992-04-01), Chaumette et al.
Barefoot Galen L.
Centre National d'Etudes Spatiales
LandOfFree
Braking shield for a spacecraft, and a satellite fitted therewit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Braking shield for a spacecraft, and a satellite fitted therewit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Braking shield for a spacecraft, and a satellite fitted therewit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1417710