A method for desaturating reaction wheels of a spacecraft having a magnetic dipole is provided. The method includes orienting the spacecraft relative to an external magnetic field to apply a torque to the spacecraft via the magnetic dipole in a direction opposing momentum stored in the reaction wheels; and using the applied torque to unload at least some of the momentum stored in the reaction wheels. A corresponding spacecraft and non-transitory computer-readable medium are also provided.

A multi-mode thruster system for use in a spacecraft includes a microwave source; a cavity coupled to the microwave source and including a first inlet to receive a first fluid and a second inlet to receive a second fluid; and a nozzle provided at one end of the cavity. The thruster operates in a microwave electrothermal thruster (MET) mode to (i) generate a standing wave in the cavity using the microwave source and (ii) raise a temperature of the first fluid to generate a first hot gas that exits the cavity via the nozzle to generate thrust. The thruster operates in a chemical propulsion mode to (i) produce a reduction-oxidation reaction between the first fluid and the second fluid and (ii) generate a second hot gas that exits the cavity via the nozzle to generate thrust.

A spacecraft propulsion system comprises two thrusters, each operating in accordance to a corresponding propulsion technique. A controller is configured to direct collected solar energy to heat a propellant for consumption in one of the two thrusters, or to generate electric energy for the other one of the two thrusters.

To efficiently delivering payloads to respective orbits, a payload is received from a launch vehicle at a spacecraft operating as an orbital transfer vehicle. The payload is transferred, using the spacecraft, to a second orbit in accordance with a predefined fixed schedule that specifies at least the second orbit and a plurality of times at which the spacecraft transitions between the first and the at least second orbit.

A system for determining an initial orbit of an object launched from an orbiting launch vehicle has a sensor affixed to the launch vehicle. The sensor transmits electromagnetic signals toward the launched object launched and receives signals reflected therefrom as reflected signals. A navigation subsystem determines a relative position of the sensor to the earth. A command and data handling subsystem receives the reflected signals and the determined relative position to the earth and determines a position of the object launched from the launch vehicle relative to earth.

Feedback control circuitry includes rate limiter circuitry configured to generate a rate limited position command based on a position command for a controlled component and based on a speed command for the controlled component. The feedback control circuitry also includes error adjustment circuitry configured to apply a control gain to an error signal to generate an adjusted error signal. The error signal is based on position feedback and the rate limited position command, and the position feedback indicates a position of the controlled component. The feedback control circuitry further includes an output terminal configured to output a current command generated based on the adjusted error signal.

The disclosure relates to a method and apparatus of rotating mass attitude control. The method and apparatus entails rotating a mass to generate thrust. Varying the speed and direction of rotation provides some control of the magnitude and direction of the thrust generated. The method and apparatus of the invention pertinent to an attitude control system for spacecrafts or astromotive vehicles under conditions of zero to low gravity and atmosphere.

A thruster system for use in a spacecraft includes a microwave source, a resonant cavity coupled to the microwave source, wherein the microwave source is configured to generate a standing wave field in the resonant cavity, a nozzle provided at one end of the resonant cavity; and at least one injector configured to inject propellant into the resonant cavity so as to create a rotating circumferential flow. The standing wave field raises a temperature of the injected propellant to provide thrust by way of a hot gas exiting the resonant cavity via the nozzle.

A space vehicle includes one or more magnetorquers operable to change an attitude of the space vehicle in an external magnetic field, each magnetorquer comprising a coil, and a switching circuit for short-circuiting the coil of at least one of the magnetorquers so that a closed electric circuit comprising said coil is formed, for damping tumbling motion of the space vehicle in the external magnetic field. The switching circuit is configured to short-circuit the coil of the at least one magnetorquer upon occurrence of a condition indicative of end-of-life or failure of the space vehicle. The application further relates to a corresponding method of operating a space vehicle.

A control system for reducing disturbance torque of a spacecraft is disclosed. The spacecraft revolves around a celestial body surrounded by an atmosphere. The control system includes processors in electronic communication with one or more actuators and a memory. The memory stores data into a database and program code that, when executed by the one or more processors, causes the control system to instruct the spacecraft to enter a safing mode. In response to entering the safing mode, the control system instructs the one or more actuators to align a principal axis of the spacecraft with a vector that is normal to the orbit around the celestial body. The control system also instructs the actuators to rotate the spacecraft about the principal axis, where a rotational orientation of the spacecraft relative to the celestial body is shifted by about one-half a rotation about the principal axis.