Aeronautics and astronautics – Spacecraft – Attitude control
Patent
1997-09-26
2000-05-16
Poon, Peter M.
Aeronautics and astronautics
Spacecraft
Attitude control
244173, 136292, B64G 136
Patent
active
060625112
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to space applications, and more particularly to a device for angularly positioning a solar panel equipping a spacecraft such as a satellite.
BACKGROUND OF THE INVENTION
The electrical power delivered by a solar panel depends in particular on its surface area and on the angle of incidence of the solar radiation on the panel. The efficiency per unit area of a solar panel can be defined as the electrical power produced per unit area of the panel. When a solar panel is fixed to the body of a satellite without it being possible to change the angular position of the panel relative to the body of the satellite, the efficiency per unit area depends directly on the angular position of the satellite relative to the sun. Since the angular position of the satellite changes as it travels over its orbit, the mean efficiency per unit area over one revolution is quite low.
To increase the mean efficiency per unit area, it has been proposed to mount the solar panel in a hinged manner on the body of the satellite and to angularly position the panel as well as possible relative to the incident solar flux by means of one or more electric motors and of their control electronic circuitry controlled by a processing unit on board the satellite (which unit manages all of the equipment on board the satellite). The angular positioning device operating properly thus depends on the control electronic circuitry and the processing unit on board the satellite operating properly. This is a drawback insofar as failure of any of these elements might cause a drop in the output of electrical energy, and ultimately might cause all of the electrical equipment on the satellite to stop. Another drawback lies in the complexity of the angular positioning device and in the associated risk of breakdown.
It has also been proposed to equip a space vehicle with a heat-sensitive device suitable for generating torque as a function of exposure to solar radiation, and designed to avoid oscillation phenomena (U.S. Pat. No. 3,311,322).
A heat-sensitive device has also been proposed that is actuated by solar radiation and that is suitable for generating torque for angularly positioning solar panels (U.S. Pat. No. 3,635,015).
SUMMARY OF THE INVENTION
The present invention provides a device for angularly positioning a solar panel equipping a spacecraft such as a satellite, the panel being connected in hinged manner to the body of the spacecraft, the device comprising a heat-sensitive drive mechanism suitable for causing the panel to be displaced relative to the body of the spacecraft as a function of the direction of incidence of the solar radiation on the spacecraft, said device being characterized in that said drive mechanism is designed to take up automatically, under the effect of its temperature, one or other of two states which differ from each other by a rotation through a determined angle, the first state being taken up for temperatures lower than a first value, and the second state being taken up for temperatures higher than a second value, said drive mechanism being connected to the panel so that said rotation is transmitted to the panel, and said drive mechanism being designed so that a predetermined change in the direction of incidence of the solar radiation on the spacecraft is accompanied by a change in the temperature of the drive mechanism causing said temperature to go from a a value lower than said first value to a temperature higher than said second value, or vice versa.
In a preferred embodiment of the invention, said drive mechanism is disposed on the spacecraft so that a predetermined change in the direction of incidence of the solar radiation on the spacecraft is accompanied by a variation in the temperature of the drive mechanism, and causes a change in the state thereof and in the angular position of the panel tending to reduce the angle of incidence of the solar radiation on the panel.
In a preferred embodiment of the invention, the drive mechanism is made of a double-acting sh
REFERENCES:
patent: 3304028 (1967-02-01), Dryden
patent: 3311322 (1967-03-01), Zimmerman
patent: 3630020 (1971-12-01), Chase et al.
patent: 4091799 (1978-05-01), Steiner
patent: 4155524 (1979-05-01), Marello et al.
patent: 5257759 (1993-11-01), Bender
patent: 5310144 (1994-05-01), Salvatore et al.
Centre National d'Etudes Spatiales
Poon Peter M.
Shaw Elizabeth
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