Satellites having autonomously deployable solar arrays are disclosed. A disclosed example satellite includes a solar array, a sensor to detect that the satellite has exited a launch vehicle, a processor to, based on the satellite exiting the launch vehicle, enable release of magnets or locks of an array, a release controller to control the release of the magnets or the locks of the array based on a release sequence to autonomously deploy the solar array, and a sequence analyzer to adapt the release sequence during execution of the release sequence, wherein adapting the release sequence includes changing an order in which the magnets or the locks of the array are released based on a degree to which the solar array is unfolded.

Methods, systems, and apparatus for designing, constructing and using instrument landers for in situ exploration of small solar system bodies, such as asteroids and comets. In one aspect, a lander includes a CubeSat-style platform; instrument packaging, wherein the CubeSat-style platform and the instrument packaging are configured and arranged for an uncontrolled descent, hopping landing on a surface of a body in a solar system, where a descending trajectory for the lander is designed based on gravitational force and solar radiation, with no lander-based propulsion; and a mobility mechanism configured and arranged to self-orient the lander on the surface of the body in the solar system.

A three-loop inertial stabilization system with active jitter suppression and optical control to reduce line-of-sight (LOS) jitter based on platform induced motion in cantilevered gimbal systems. A first loop comprises at least one rate sensor, a Kalman state estimator, and a rate to angle module. A second loop comprises a mirror system, a focal plane and centroid processing module, an open-loop closed loop selector, a signal combiner and a loop integrator. A third loop comprises a fast steering mirror, offload module and at least one gimbal motor driver, wherein the three loops suppress the jitter of the cantilevered gimbal system.

A device for determining an attitude of a satellite is disclosed, the satellite having an attitude control system comprising a gyroscopic actuator including a flywheel mounted so as to be rotatable around an axis of rotation and carried by a gimbal articulated to rotate around an axis of rotation. The device includes an attitude sensor configured to measure the attitude of the satellite, a position sensor configured to measure the angular position of the gimbal around its axis of rotation, a speed sensor configured to measure the rotational speed of the flywheel, and a processing circuit configured to determine the attitude of the satellite by using the measurement of the angular position of the gimbal, the measurement of the rotational speed of the flywheel, and the measurement of the attitude of the satellite.

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.

Conductive cooled gimbaled inertial measurement units are disclosed herein. An example apparatus includes an inertial measurement unit, a gimbal assembly in which the inertial measurement unit is disposed, the gimbal assembly having gaps between each gimbal of the gimbal assembly, the gaps including a gas to conduct heat from the gimbal assembly, and an isothermal dome at least partially surrounding the gimbal assembly, the isothermal dome having a cooling tube disposed on an external surface of the isothermal dome to transfer heat from the gimbal assembly via conduction.

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.

Apparatus and methods for controlling a spacecraft for a transfer orbit. The spacecraft includes a propulsion subsystem with electric thrusters that are installed with two-axis gimbal assemblies. The spacecraft also includes a controller that identifies a target spin axis for the spacecraft, determines an actual spin axis for the spacecraft during the transfer orbit, determines gimbal angles for the electric thruster(s) that adjust the actual spin axis toward the target spin axis, and initiates a burn of the electric thruster(s) at the gimbal angles.

A modular satellite for converting solar energy to microwave energy and transmitting the microwave energy to the earth to be converted into electricity includes solar panels configured to convert solar energy into direct current; a magnetron operatively connected to the solar panels to receive the direct current and configured to convert the direct current into microwave energy; a planar wave guide antenna operatively connected to the magnetron to receive the microwave energy and direct the microwave energy to a station on earth; and a coupling system for coupling with another satellite to form an array in response to at least one of locking, unlocking, and navigational commands. The satellite has a mass equal to or less than four kilograms, and a volume equal to or less than three liters.

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.