摘要:
Methods and apparatus to methods and apparatus for performing propulsion operations using electric propulsion system are disclosed. An example apparatus includes a frame (207, 209), a power source (104) coupled to the frame and a payload (106)coupled to the frame, the payload to receive or transmit data. The apparatus also includes an electric propulsion system (108)coupled to the frame. The electric propulsion system is to enable attitude control, momentum control, and orbit control of the apparatus.
摘要:
Beschrieben wird ein Verfahren zum Betrieb eines Raumfahrzeugs (1), das zumindest eine mit einem Himmelskörper zusammenwirkende Einrichtung (2,3) aufweist, wobei eine Rotation des Raumfahrzeuges um zumindest eine Körperachse des Raumfahrzeuges erfolgt. Die Rotation des Raumfahrzeuges wird verlangsamt, wenn die mit dem Himmelskörper zusammenwirkende Einrichtung im wesentlichen in Richtung des Himmelskörpers ausgerichtet ist.
摘要:
A method for use on a satellite that automatically inhibits scanning of an Earth sensor to handle sensor intrusions by the sun, moon, or other celestial bodies. In implementing the method, a predicted state vector for the satellite, derived from an orbit propagator, is generated. An attitude profile for the satellite is generated. Then, the satellite state (predicted state vector) and attitude profile are processed to determine Earth, sun, and moon vectors in a satellite body frame of reference at any instant. The Earth, sun, and moon vector are compared to the Earth sensor field of view and sensor field of view limit boxes to determine if scan inhibiting or Earth sensor switching should occur. The affected Earth sensor is inhibited or switched if an intrusion of the sun and/or moon into the field of view of the Earth sensor is predicted.
摘要:
Satellite control data in the form of state vectors and state vector products are generated representing the position and geometric relationships of the space craft to the Earth, sun, moon, and specific locations on the Earth. These data is used to control attitude, SADA steering, antenna pointing, momentum upload, and Earth sensor intrusion. An onboard orbit propagator (1) predicts the data and integrates the data into the various control systems for the respective function.
摘要:
For an antenna (22) on a satellite (10) in an inclined orbit about the Earth (13), cross-track motion resulting from the rotation of the Earth (13) can be reduced in antenna coordinates by yawing and/or rolling the antenna (22) (preferably by yawing and/or rolling the entire satellite (10), for example, by using a reaction wheel system) by an appropriate angle, which varies throughout the orbit (12) (Fig. 4).
摘要:
A spacecraft orientation procedure, in accordance with a first embodiment of the invention, is practiced with a sun sensor to bring the x (roll) axis of the spacecraft parallel to a ray of the sun, and with a gyro sensor and an earth sensor of the spacecraft in conjunction with one instruction provided either autonomously or by a ground tracking station regarding an orientation of a spacecraft reference plane to enable locating the earth by the earth sensor. Furthermore, in accordance with a second embodiment of the invention, the orientation is established without aid from the ground tracking station by use of at least one telemetry and command antenna having a continuous field of view, as measured in one plane, which is greater than a semicircle.' In the second embodiment, the orientation procedure provides for rotation of the spacecraft about the x axis for a scanning of the antenna to intercept command signals broadcast from the earth, thereby to locate the earth in a first reference plane. Rotation about the y (pitch) axis enables measurement of command signal strength for location of the earth in a second reference plane perpendicular to the first reference plane. Gyrocompassing establishes yaw in both embodiments of the invention.