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.

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.

A rotor assembly for deployment within a momentum control device that enables near-zero revolutions per minute (RPM) sensing, and method for making same, are provided. The provided rotor assembly utilizes a magnet coupled to the rotor shaft and a stationary sensor element to detect magnetic flux from the magnet and derive reliable near zero RPM therefrom.

A hybrid power source and control moment gyroscope (“HPCMG”) is disclosed. The HPCMG includes a control moment gyroscope (“CMG”), a first conductive bearing, and a second conductive bearing. The CMG includes a first transverse gimbal assembly, a central mass that produces a voltage potential, and a second gimbal assembly rotationally connected to the first transverse gimbal assembly. The first transverse gimbal assembly is rotationally connected to the central mass along a first axis of rotation and the central mass is configured to spin about the first axis of rotation and the first transverse gimbal assembly is configured to rotate about a second axis of rotation of the second gimbal assembly. The first conductive bearing rotationally connects the central mass with the first position of the first transverse gimbal assembly along the first axis of rotation.

An operation of a spacecraft is controlled using an inner-loop control determining first control inputs for momentum exchange devices to control an orientation of the spacecraft and an outer-loop control determining second control inputs for thrusters of the spacecraft to concurrently control a pose of the spacecraft and a momentum stored by the momentum exchange devices of the spacecraft. The outer-loop control determines the second control inputs using a model of dynamics of the spacecraft including dynamics of the inner-loop control, such that the outer-loop control accounts for effects of actuation of the momentum exchange devices according to the first control inputs determined by the inner-loop control. The thrusters and the momentum exchange devices are controlled according to at least a portion of the first and the second control inputs.

Embodiments of a spherical momentum control device are provided. In one embodiment, the spherical momentum control device includes a housing assembly bounding a cavity, a rotor support axle disposed within the cavity, and a spherical bearing interface formed between the rotor support axle and the housing assembly. The spherical bearing interface facilitates rotation of the rotor support axle within the cavity about three orthogonal axes transecting substantially at the cavity center point. A rotor is mounted to the rotor support axle (e.g., through precision bearings) for rotation about a spin axis. The spherical bearing interface can assume any form for facilitating rotation of the rotor support axle about the orthogonal axes including, for example, a low friction plane bearing interface. In one embodiment, the spherical bearing interface includes rolling element bearings embedded in the cavity walls or embedded in enlarged end caps forming part of the rotor support axle.

Described herein are systems and methods for attitude determination using infrared Earth horizon sensors (EHSs) with Gaussian response characteristics. Attitude information is acquired by detecting Earth's infrared electromagnetic radiation and, subsequently, determining the region obscured by Earth in the sensors' fields of view to compute a nadir vector estimation in the spacecraft's body frame. The method can be applied when two sensors, each with known and distinct pointing directions, detect the horizon, which is defined as having their fields of view partially obscured by Earth. The method can be implemented compactly to provide high-accuracy attitude within small spacecraft, such as CubeSat-based satellites.

Systems and methods for describing, simulating and/or optimizing spaceborne systems and missions. Configurations for spaceborne systems are generated and validated based on simulation output.

Systems and methods for transferring, storing, and/or processing materials, such as fuel or propellant, in space, are disclosed. A representative system includes a flexible container that is changeable between a stowed configuration in which the flexible container is contained within a satellite, and a deployed configuration in which the flexible container extends away from the satellite. The system can include a tanker with a storage container to dock with and refuel a satellite. Another representative system includes a controller programmed with instructions that position a spacecraft with a storage container in a first orbit, transfer the spacecraft to a second orbit, dock the spacecraft with a satellite in the second orbit, transfer material between the storage container and the satellite, undock the spacecraft from the satellite, and, optionally, return the spacecraft to the first orbit. An androgynous coupling system with mechanical and fluid connectors facilitates docking and material transfer.