Abstract: A method for pointing control of a laser communication terminal on a spacecraft may include measuring a line-of-sight (LOS) error of the laser communication terminal. The method may also include estimating a LOS error of the laser communication terminal based on measurements from a spacecraft gyro and a gimbal gyro onboard the spacecraft. The method may further include switching from a LOS error measurement feedback to a LOS error estimate feedback to control pointing of the laser communication terminal during a power fade condition.

Abstract: Method and system for determining a point-ahead angle from a first spacecraft to a second spacecraft, each spacecraft having a laser communication (“lasercom”) terminal is provided If ephemeris data regarding the second spacecraft is unavailable to the first spacecraft while the second spacecraft is mobile, (a) obtaining attitude information regarding the first spacecraft; and (b) obtaining gimbal offload commands from a fast steering mirror and a first spacecraft telescope subsystem of the first spacecraft; wherein a point-ahead determination module receives the attitude information and the gimbal offload commands; and determining an estimate of the point-ahead angle from the first spacecraft to the second spacecraft based on the attitude information and the gimbal offload commands.

Abstract: A system for determining and controlling an orbit of a spacecraft may include a GPS receiver mounted to the spacecraft to receive GPS information from a plurality of GPS satellites visible to the GPS receiver for determining a position of the spacecraft relative to a reference coordinate system. The system may also include a filter configuration control module to sense a thruster maneuver operation to adjust the orbit of the spacecraft. The system may also include an orbit determination filter to determine at least one of a spacecraft position, velocity, and residue acceleration based on the GPS information and information from the filter configuration control module related to the thruster maneuver operation.

Abstract: A system and method for SpaceWire network management are disclosed involving a network and a network manager (NM). The network includes a plurality of switches and a plurality of nodes. The switches and nodes do not have any preprogrammed knowledge of the network topology and/or of their unit identification (UID) code. In one or more embodiments, the network is a spacecraft communications network. In at least one embodiment, the method for managing the SpaceWire network comprises the network manager (NM) determining link connectivity of the network; verifying the switches are properly configured to allow for logical address routing; and verifying the nodes are configured to process, receive, and transmit data through the network. In some embodiments, the method further comprises determining newly added units, removed units, and/or unresponsive units in the network, and propagating this information through an active unit table.

Abstract: In accordance with an embodiment of the present invention, a resolver system has at least one resolver and at least one amplifier in electrical communication with each resolver. A reference circuit is in electrical communication with the amplifiers. The reference circuit provides reference signals to the amplifiers. A non-linearity calibration and compensation circuit in communication with each amplifier uses the amplified reference signals to provide scale factors, so as to enhance a precision of the resolver system.

Abstract: A method and apparatus for determining the attitude of a satellite using crosslink information is disclosed. The method and apparatus integrates data from the crosslinks with data available from other sources including, for example, star sensors, inertial sensors, and earth limb sensors to derive an accurate estimate of the satellite attitude, even in harsh nuclear environments.

Abstract: Systems and techniques for laser metrology. Two or more fanned probe beams are scanned relative to a surface including one or more targets. A position detection module receives return beam information from the fanned probe beams, and determines a position of at least a first target of the one or more targets based on the return beam information.

Abstract: Method and system for determining a point-ahead angle from a first spacecraft to a second spacecraft, each spacecraft having a laser communication (“lasercom”) terminal is provided If ephemeris data regarding the second spacecraft is unavailable to the first spacecraft while the second spacecraft is mobile, (a) obtaining attitude information regarding the first spacecraft; and (b) obtaining gimbal offload commands from a fast steering mirror and a first spacecraft telescope subsystem of the first spacecraft; wherein a point-ahead determination module receives the attitude information and the gimbal offload commands; and determining an estimate of the point-ahead angle from the first spacecraft to the second spacecraft based on the attitude information and the gimbal offload commands.

Abstract: In accordance with an embodiment of the present invention, a resolver system has at least one resolver and at least one amplifier in electrical communication with each resolver. A reference circuit is in electrical communication with the amplifiers. The reference circuit provides reference signals to the amplifiers. A non-linearity calibration and compensation circuit in communication with each amplifier uses the amplified reference signals to provide scale factors, so as to enhance a precision of the resolver system.

Abstract: One or more fixed-orientation fanned laser beams and one or more displacement measurement devices to precisely measure the orientation of a payload platform are disclosed in a metrology system and method. The measurement devices may be distributed at locations across a payload platform such that displacement changes of these devices can be used to accurately determine platform pointing. Laser beam transmitters may be fixed in the same reference block to which a spacecraft attitude sensor is mounted. Fanned laser beams are transmitted from these sources to the measurement devices so that their displacements can be determined with respect to the plane of the fanned beams and thereby with respect to the spacecraft attitude sensor. Only a small number of fixed laser beams are needed to achieve precision measurements at a reduced cost, weight and power, and with increased system reliability and simplified system integration.

Abstract: A method and apparatus for determining the attitude of a satellite using crosslink information is disclosed. The method and apparatus integrates data from the crosslinks with data available from other sources including, for example, star sensors, inertial sensors, and earth limb sensors to derive an accurate estimate of the satellite attitude, even in harsh nuclear environments.

Abstract: Systems and techniques for laser metrology. A system may include a laser source and a fanning apparatus configured to generate a fanned laser beam. The fanned laser beam may be scanned across the surface of an object, and may reflect off a plurality of targets positioned on the surface. A position detection module may determine a position of the metrology targets based on the reflected beam.

Abstract: Various embodiments of the present invention are directed to precision control system for spacecraft gimbaled payloads. Embodiments of the invention provide an innovative technique of calibrating gimbals disturbances to directly canceling gimbal control disturbances. Such a calibration system includes a receiver for receiving telemetry data for pointing a payload, a processor for calculating a disturbance parameter vector for a gimbal disturbance model with the telemetry data and a transmitter for transmitting the disturbance parameter vector to compensate for pointing error when applied in pointing the payload. The gimbal disturbance model comprises a harness stiffness term, a disturbance harmonics term and at least one friction hysteresis term. The telemetry data may be time matched prior to calculating the disturbance parameter vector.

Abstract: A method and apparatus for controlling a gimbaled platform (108). The method comprises the steps of computing an acquisition phase gimbal angle rate command ?cmd—Acq (530) from a measured LOS angle error ??LOS (520) for an initial control period T while computing an estimated LOS angle rate {circumflex over (?)}LOS (524), computing a tracking phase gimbal angle rate command ?cmd—Trk (532) using a controller (512) having an output initialized with the estimated LOS angle rate {circumflex over (?)}LOS (524), and commanding the gimballed platform (108) according to an angle rate command ?cmd (522), wherein the angle rate command ?cmd (522) is the acquisition phase angle rate command ?cmd—Acq (530) during the initial control period T and the tracking phase gimbal angle rate command ?cmd—Trk (532) after the initial control period T.

Abstract: A precision antenna pointing system and methods are disclosed. Antenna pointing error is determined by detecting RF signal phases at locations along the edge of an antenna reflector. A set of signal phase reference harnesses are used to compensate for harness induced errors. Furthermore, multiplexing is used to minimize electronics induced phase errors.

Abstract: A precision antenna pointing system and methods are disclosed. Antenna pointing error is determined by detecting RF signal phases at locations along the edge of an antenna reflector. A set of signal phase reference harnesses are used to compensate for harness induced errors. Furthermore, multiplexing is used to minimize electronics induced phase errors.

Abstract: In accordance with an embodiment of the present invention, a resolver system has at least one resolver and at least one amplifier in electrical communication with each resolver. A reference circuit is in electrical communication with the amplifiers. The reference circuit provides reference signals to the amplifiers. A non-linearity calibration and compensation circuit in communication with each amplifier uses the amplified reference signals to provide scale factors, so as to enhance a precision of the resolver system.

Abstract: One or more fixed-orientation fanned laser beams and one or more displacement measurement devices to precisely measure the orientation of a payload platform are disclosed in a metrology system and method. The measurement devices may be distributed at locations across a payload platform such that displacement changes of these devices can be used to accurately determine platform pointing. Laser beam transmitters may be fixed in the same reference block to which a spacecraft attitude sensor is mounted. Fanned laser beams are transmitted from these sources to the measurement devices so that their displacements can be determined with respect to the plane of the fanned beams and thereby with respect to the spacecraft attitude sensor. Only a small number of fixed laser beams are needed to achieve precision measurements at a reduced cost, weight and power, and with increased system reliability and simplified system integration.

Abstract: A system and associated method for compensating for thermal deformation of a spaced-based structure having a spacecraft payload. The system including a beacon source coupled to a first spacecraft for transmitting a first signal and a beacon sensor coupled to a second spacecraft for receiving the first signal and providing measurement data derived from the first signal. At least one attitude sensing device is coupled to the second spacecraft for determining estimated spacecraft attitude data for the second spacecraft. A processor on the second spacecraft is configured to process ephemeris data of the first and second spacecraft, beacon measurement data, estimated spacecraft attitude data, and gimbal angular position data to estimate spacecraft structural deformation.

Abstract: A laser metrology system for estimating the deformation of a structure is provided. The system includes a plurality of laser beam position detectors distributed across a surface of the structure. Each laser beam position detector is intersected by a laser beam and is configured to determine the change in location of the intersection point in at least one dimension. By determining the change in location of the intersection point for each laser beam position detector, the laser metrology system can calculate the deformation of the structure that caused these changes in location.