An attitude control module is described for providing propellant-free attitude control and momentum desaturation to a spacecraft. The attitude control module includes at least one solar sail comprising a reflective surface for reflecting solar photons; and at least one robotic arm coupled to the at least one solar sail, said at least one robotic arm comprising at least 4 degrees of freedom for positioning and orienting the at least one solar sail relative to the spacecraft. A corresponding method for operating the attitude control module to unload excess momentum from a spacecraft is also described.

A new approach for rapid slew and settle of small satellites is based on four single degree-of-freedom control moment gyroscopes with variable speed flywheels (or reaction wheels) in a pyramid configuration, combined with path and endpoint constraint time-optimal control. The path and endpoint constrained time-optimal control can be augmented with momentum management without the use of additional actuators.

A satellite in orbit around a planetary body includes a bus and a drag flap coupled to the bus. The drag flap is used to increase the drag torque applied to the satellite. The bus may house sensors and actuators, such as a star tracker, a gyroscope, a reaction wheel, and a global position system (GPS) receiver to monitor the attitude of the satellite in response to the applied drag torque. The measurements from the sensors and actuators may be used to determine the drag torque applied to the satellite. An estimate of the atmospheric density may be then be determined based on the drag torque. Compared to conventional approaches, the satellite and methods described herein estimates the atmospheric density at comparable, if not better, resolution and bandwidth. The atmospheric density estimates may also be acquired in real-time using a cheaper, lighter, and smaller satellite.

A reaction compensated steerable platform device is disclosed. The reaction compensated steerable platform device can include a base, a steerable platform movably coupled to the base, and a reaction mass movably coupled to the base. The reaction compensated steerable platform device can also include a primary actuator coupled to the steerable platform and the base to cause movement of the steerable platform. The reaction compensated steerable platform device can further include a secondary actuator coupled to the reaction mass and the base to cause movement of the reaction mass. In addition, the reaction compensated steerable platform device can also include a load sensor configured to provide feedback for actuation of the secondary actuator, such that the reaction mass moves to compensate for a load induced on a support structure by the movement of the steerable platform.

A reaction compensated steerable platform device is disclosed. The reaction compensated steerable platform device can include a base, a steerable platform movably coupled to the base, and a reaction mass movably coupled to the base. The reaction compensated steerable platform device can also include a primary actuator to cause movement of the steerable platform, and a trim actuator coupled to the reaction mass and the base. In addition, the reaction compensated steerable platform device can include a sensor configured to provide feedback for actuation of the trim actuator. The reaction mass can be configured to move by actuation independent of the trim actuator to compensate for a first portion of a load induced by the movement of the steerable platform. Actuation of the trim actuator can be controlled by the sensor, such that the reaction mass moves to compensate for a second portion of the load induced by the movement of the steerable platform.

A Fiber-fed Pulsed Plasma Thruster (FPPT) utilizes a motor to feed PTFE fiber to its discharge region, enabling high PPT propellant throughput and variable exposed fuel area. A highly parallel ceramic capacitor bank lowers system specific mass. Impulse bits (I-bits) from 0.057-0.241 mN-s have been measured on a thrust stand with a specific impulse (Isp) of 900-2400 s, representing an enhancement from state-of-the-art PPT technology. A 1 U (10 cm×10 cm×10 cm, or 1 liter) volume FPPT thruster package will provide 2900-7700 N-s total impulse, enabling 0.6-1.6 km/s delta-V for a 5 kg CubeSat. A 1 U design variation with 590 g propellant enables as much as .sup.˜10,000 N-s and a delta-V of 2 km/s for a 5 kg CubeSat. Increasing the form factor to 2U increases propellant mass to 1.4 kg and delta-V to 10.7 km/s for an 8 kg CubeSat.

A spacecraft nutation inhibition method for low-orbit geomagnetic energy storage in-orbit delivery includes: S1, enabling a delivery connection rod to be slidably connected to two mass blocks in a length direction, and adjusting the center of mass of a spacecraft system to pass through a main connecting shaft; S2, respectively measuring, calibrating and adjusting the center of mass and the principal axis of inertia of the delivery connection rod that is to deliver the space target or de-orbit debris; S3, carrying out energy storage delivery; S4, respectively adjusting the center of mass and the moment of inertia of the delivery connection rod after delivering the space target or de-orbit debris; S5, carrying out energy dissipation and unloading; and S6, enabling the spacecraft system to prepare to grab the next space target or de-orbit debris and proceeding to the next delivery work cycle.

Apparatus and methods for controlling a spacecraft for a transfer orbit. The spacecraft includes a momentum subsystem that stores angular momentum relative to a center of mass of the spacecraft, and a propulsion subsystem that includes electric thrusters. A controller identifies a target spin axis for the spacecraft, determines gimbal angles for electric thruster(s) that so that thrust forces from the electric thrusters are parallel to the target spin axis, and initiates a burn of the electric thruster(s) at the gimbal angles. The controller controls the momentum subsystem to compensate for a thruster torque produced by the burn of the electric thrusters. The momentum subsystem is able to produce a target angular momentum about the center of mass, where a coupling between the target angular momentum and an angular velocity of the spacecraft creates an offset torque to counteract the thruster torque.

An apparatus includes a satellite in the form of a plate having a thickness being smaller than a width of the satellite. The apparatus also includes a plurality of contact points distributed on a face of the satellite, allowing for one or more additional satellites to be stacked upon the satellite.

For power-enhanced slew maneuvers, a method determines a power collection function for a satellite. The method determines a power cost function for the satellite. The method calculates a power enhanced slew maneuver based on the power collection function and the power cost function.