Abstract: Technology is disclosed herein for reverse current protection for a photovoltaic module string. An apparatus has a switch connected between each respective PV module string and a power bus. A control circuit closes a set of the switches to connect a set of the PV module strings to the power bus to transfer power from the set of the photovoltaic PV module strings to the power bus. The control circuit determines whether a reverse current flows in the direction from the power bus to any of the PV module strings. The control circuit maintains the switch associated with a particular PV module string in an open state to prevent reverse current from flowing in the particular PV module string responsive to a determination that a reverse current flows in the particular PV module string when the particular PV module string is connected to the power bus.

Abstract: Technology is disclosed herein for a power control and distribution unit (PCDU) of a spacecraft that has a microcontroller to control battery charging from solar arrays. Using a microcontroller within the PCDU reduces the complexity of the PCDU. The microcontroller may be programmable and reprogrammable, which allows the charging of the battery to be adapted to various conditions. For example, the microcontroller can be programmed in accordance with the mission to optimize battery charging for that mission.

Abstract: Technology is disclosed herein for orbit raising of multiple spacecraft launched with a single launch vehicle. Two or more spacecraft are configured in a stacked launch configuration in which a lower spacecraft is mechanically coupled with a payload adapter of a launch vehicle with one or more upper spacecraft above the lower spacecraft. Propellant that is stored in the lower spacecraft during launch is transferred to an upper spacecraft in the stack after launch. The propellent may be used by the upper spacecraft for an orbit raising maneuver that raises the orbit of at least the upper spacecraft from a first orbit to a second orbit. Storing the propellant in the lower spacecraft lowers the center of mass of the stack during launch. Lowering the center of mass reduces the structural bending moment of the stack during launch, which allows a greater total launch mass.

Abstract: Technology is disclosed herein for using an antenna reflector to regulate a spacecraft temperature during orbit raising. When in a launch configuration, the antenna reflector may be stowed in a fairing of a launch vehicle. After the spacecraft is deployed from the launch vehicle and prior to orbit raising, the antenna reflector is moved from the launch configuration to an orbit raising configuration in which the antenna reflector is used to regulate the spacecraft temperature. The antenna reflector may be proximate a thermal radiator panel of the spacecraft when in the launch configuration. The antenna reflector may be positioned such that sunlight will reflect off the antenna reflector onto the thermal radiator panel, thereby warming the spacecraft. After orbit raising, the antenna reflector is moved from the orbit raising configuration to an operational configuration in which a boresight of the antenna reflector may be directed toward nadir.

Abstract: Techniques for minimizing diurnal temperature variation of a radiator of a spacecraft are disclosed. In one aspect, a spacecraft includes a body, a radiator panel, and a heat dissipating unit thermally coupled with the radiator panel. The spacecraft is configured to operate in an orbital plane, and has a yaw axis within the orbital plane and directed from a spacecraft coordinate system origin toward nadir, a pitch axis orthogonal to the orbital plane, and a roll axis orthogonal to the pitch axis and the yaw axis. The radiator panel includes a surface area external to a body of the spacecraft, a first portion of the surface area facing a first direction that is substantially parallel to the roll axis, and a second portion of the surface area facing a second direction that has a substantial component parallel to the yaw axis.

Abstract: A universal test port is connected to the different functional sub-systems of a spacecraft, allowing the sub-systems to be tested from a single location of an assembled spacecraft. The universal test port is mounted on an external surface of the spacecraft and configured to connect to the different functional sub-systems (such as power, propulsion, and command and data handling, for example) of the assembled spacecraft, allowing for the streamlining of testing operations by electrical ground system equipment during assembly, integration, and test (AIT) operations and reducing the risk of collateral damage to spacecraft hardware during testing in AIT.

Abstract: Technology is disclosed herein for reverse current protection for a photovoltaic module string. An apparatus has a switch connected between each respective PV module string and a power bus. A control circuit closes a set of the switches to connect a set of the PV module strings to the power bus to transfer power from the set of the photovoltaic PV module strings to the power bus. The control circuit determines whether a reverse current flows in the direction from the power bus to any of the PV module strings. The control circuit maintains the switch associated with a particular PV module string in an open state to prevent reverse current from flowing in the particular PV module string responsive to a determination that a reverse current flows in the particular PV module string when the particular PV module string is connected to the power bus.

Abstract: An apparatus includes an integral, additively manufactured, actuation device having a rigid portion comprising a shaped structural member and a flexible portion comprising a helical torsion spring. In a spacecraft application, a spacecraft appendage may be coupled with a deployment mechanism, the deployment mechanism including at least one integral, additively manufactured, actuation device having a rigid portion comprising a shaped structural member and a flexible portion comprising a helical torsion spring.

Abstract: An example of an apparatus includes an inlet to connect to a propellant source a pressure regulator connected to the inlet to reduce propellant pressure from a first pressure at the inlet to a second pressure. The apparatus includes a manifold connected to the pressure regulator to receive propellant from the pressure regulator at the second pressure and includes a plurality of manifold outlets. The apparatus further includes a plurality of gas lines, each gas line extending from a corresponding manifold outlet for connection to a corresponding satellite propellant tank.

Abstract: An example apparatus includes a first 3D printer head configured to form a spiral structure around a hub and a second 3D printer head configured to form a boom extending between the second 3D printer head and the hub. The apparatus further includes one or more actuators coupled to the first 3D printer head and the second 3D printer head to control a distance between the first 3D printer head and the second 3D printer head.

Abstract: An apparatus comprising a satellite includes a first radiator panel on a first side of a central body of the satellite and a second radiator panel on a second side of the central body is provided. The first radiator panel is thermally attached to the second radiator panel. A third side of the central body is positioned between the first side and the second side. A fourth side of the central body is positioned between the first side and the second side, opposing the third side. The first radiator panel is thermally attached to the second radiator panel by one or more coupling heat pipes, the coupling heat pipes exposed to an exterior environment of the satellite.

Abstract: A universal external port is proposed to add new functionality to or replace existing functionality of an already deployed spacecraft (e.g., a satellite in orbit). The universal external port is mounted on an external surface of the spacecraft and configured to connect to different types of external modules that have different functions, without removing components from the spacecraft other than one or more components of the universal external port. A communication interface onboard the spacecraft is configured to wirelessly receive a software patch from an entity remote from the spacecraft (e.g., from a ground terminal or other spacecraft) to program the spacecraft to change operation of the spacecraft to utilize the external module when the external module is connected to the universal external port.

Abstract: Described herein are apparatuses and methods for use therewith that can be used to remove dust and other types of particulates from a solar array of a spacecraft, a lander, a rover, or the like. Such an apparatus can include a main body and a solar array extending from the main body. One or more piezoelectric devices is/are attached to the solar array. The piezoelectric device(s), when activated, is/are configured to vibrate at least a portion of the solar array to thereby loosen particulates adhered thereto. The apparatus also includes one or more linear actuators that when actuated is/are configured to at least one of bump against, push on, or pull on at least a portion of the solar array to thereby jettison from the solar array at least some of the particulates that were loosened by the one or more piezoelectric devices.

Abstract: Methods and structures are presented for implementing an automatic target recognition system as a convolutional neural network (CNN) in a satellite or other environment with constrained resources, such as limited memory capacity and limited processing capability. For example, this allows for the automatic target recognition to be implemented on a field programmable gate array (hdFPGA). Image data is split into subsets of contiguous pixels, with the subsets processed in parallel in a CNN of a corresponding processing node using quantized weight values that are determined in a training process that accounts for the constraints of the automatic target recognition system. The results of the automatic target recognition process is based on the combined output of the processing nodes.

Abstract: Methods and structures are presented for implementing an automatic target recognition system as a convolutional neural network (CNN) in a satellite or other environment with constrained resources, such as limited memory capacity and limited processing capability. For example, this allows for the automatic target recognition to be implemented on a field programmable gate array (FPGA). Image data is split into subsets of contiguous pixels, with the subsets processed in parallel in a CNN of a corresponding processing node using quantized weight values that are determined in a training process that accounts for the constraints of the automatic target recognition system. The results of the automatic target recognition process is based on the combined output of the processing nodes.

Abstract: A spacecraft includes a semi-rigid solar array and a main body structure, the main body structure configured as a convex polyhedron and including an aft and a forward face disposed opposite to the aft face and at least four side faces disposed between and approximately orthogonal to the aft face and the forward face. The solar array includes a number of panels linked together with flexible couplings. In an undeployed configuration, panels of the solar array cover at least two adjacent side faces, the flexible couplings providing an articulable joint approximately aligned with a line along which the two adjacent side faces are joined and connecting a first panel of the solar array and a second panel of the solar array, the first panel being proximal to a first side face and the second panel being proximal to a second side face.

Abstract: A rover includes a suspension configured to traverse uneven and unpredictable terrain, such as for example on an astronomical body. Each wheel is independently suspended off of the rover chassis with a linkage assembly comprising a pair of canted links which are able to continuously rotate relative to each other without collision or interference. The links allow the rover to independently adjust the height of each wheel relative to the chassis to drive over difficult terrain, and further allow the linkage assembly at each wheel to rotate 360° to effectively step or walk over particularly difficult terrain.

Abstract: To facilitate on-orbit servicing, such as for a refueling operation, techniques are presented for a servicing satellite to cut through the multi-layer insulation blanket of a client satellite to provide access to the client satellite without releasing unacceptable quantities of foreign object debris from the multi-layer insulation. The serving satellite includes a sealing tool, such as a pair of heater rollers, that apply pressure and heat to the insulating blanket to melt the inner layers and seal the outer layers together. The servicing satellite can then use a cutting tool to cut the sealed region and access the client satellite.

Abstract: An orbital satellite has a pair of multi-axis booms including both thrusters for course/attitude adjustment and an end effector for grappling payloads and manipulating other tools and objects. The satellite may launch with a primary payload affixed to a bus and one or more secondary payloads affixed to an ESPA ring. Once in orbit, the end effector may be used to grapple the primary and/or secondary payloads and rearrange them on the bus. In further aspects, the end effector may be used to make bus repairs or take measurements, or hold tools that are used to make bus repairs or take measurements.

Abstract: A satellite includes a plurality of thrusters disposed about the satellite, each of the plurality of thrusters having a minimum thruster firing time, and a control circuit connected to the plurality of thrusters. The control circuit is configured to identify violations of the minimum thruster firing time in a non-compliant thruster firing pattern selected to achieve a specified movement, generate a plurality of compliant thruster firing patterns by replacing each of the violations of the non-compliant thruster firing pattern by zero and a minimum time in different combinations, select a compliant thruster firing pattern from the plurality of compliant thruster firing patterns to produce a satellite movement that is within a predetermined range of the specified movement, and cause the plurality of thrusters to fire according to the compliant thruster firing pattern.