Abstract: A low earth orbiting spacecraft (LEO spacecraft) operable in a first earth orbit includes a main body, a data collection payload, and a first directional antenna, each of the data collection payload and the first directional antenna being coupled with the main body. During a first period of time, the main body is oriented such that the data collection payload views a region of interest on the earth. During a second period of time, the main body and the first directional antenna are oriented such that the first directional antenna is directed toward a first ground station. During a third period of time, the main body and the first directional antenna are oriented such that the first directional antenna is directed toward a second spacecraft operating in a second orbit.

Abstract: A spacecraft including a main body structure and at least a first deployable element is reconfigured from a launch configuration to an on-orbit configuration. In the launch configuration, the first deployable element is mechanically attached with the spacecraft main body structure by way of a first arrangement. In the on-orbit configuration, the first deployable element is mechanically attached with the spacecraft main body structure by way of a second arrangement. Reconfiguring the spacecraft includes detaching the first deployable element from the first arrangement, moving the first deployable element with respect to the spacecraft main body structure; and attaching the first deployable element to the second arrangement.

Abstract: A solid state power amplifier uses a Doherty power amplifier that can be implemented as a monolithic microwave integrated circuit. By adjusting the DC bias of the amplifying stages in each branch of the Doherty amplifier, the output power, linearity, and DC power can be adjusted to provide a specified output, where the specification for the output can include the maintaining of desired DC power and linearity. The Doherty power amplifier can be used in a satellite payload or other application utilizing solid state power amplifiers, while providing the proper amount of RF output power and DC power. A single amplifier can have its bias levels adjusted for different output levels, helping to minimize the number of designs that are required for a given satellite payload, reducing the variety of parts in a satellite payload.

Abstract: Techniques for performing an orbital maneuver on a spacecraft by firing a thruster include executing a first double pulse, double coast firing (DPDC) sequence with the thruster prior to the orbital maneuver, firing the thruster for a duration of the orbital maneuver, and executing a second DPDC firing sequence with the thruster subsequent to the orbital maneuver.

Abstract: A system includes at least two spacecraft disposed together for launch by a launch vehicle. In a launch configuration, a second spacecraft is mechanically coupled with the first spacecraft by way of an inter-spacecraft coupling arrangement (ISCA). The system is configured to be deployed following injection into a first orbit by the launch vehicle, while the second spacecraft is mechanically coupled with the first spacecraft. The first spacecraft includes a thruster configured to execute an orbit transfer maneuver from the first orbit to a second orbit, the thruster delivering thrust along a thrust vector. In an on-orbit configuration, the ISCA is switchable between a first mode that permits rotation of the first spacecraft with respect to the second spacecraft about a first axis of rotation that is approximately parallel with the thrust vector and a second mode that prevents rotation of the first spacecraft with respect to the second spacecraft.

Abstract: Described herein is a ground based subsystem for inclusion in an optical gateway and for use in transmitting an optical feeder uplink beam to a satellite. The subsystem can include a wavelength-division multiplexing (WDM) multiplexer configured to receive optical data signals from optical network(s) external to the ground based optical gateway, and configured to combine the optical data signals into a wavelength division multiplexed optical signal. The subsystem can also include an optical amplifier to amplify the wavelength division multiplexed optical signal, and transmitter optics to receive the amplified wavelength division multiplexed optical signal and transmit an optical feeder uplink beam to the satellite in dependence thereon. In certain embodiments, the ground based optical gateway does not perform any modulation or demodulation of the optical data signals received from the optical network(s) external to the ground based optical gateway before they are provided to the WDM multiplexer.

Abstract: A spacecraft includes at least a first thruster support mechanism (TSM) and a second TSM, each TSM including a pointing arrangement, an elongated structural member and thruster for performing orbit raising north-south stationkeeping, east-west stationkeeping, and momentum management. A first pointing arrangement is articulable only by way of first and second revolute joints, the first revolute joint being rotatable about a first axis fixed with respect to the spacecraft. The second pointing arrangement is articulable only by way of third and fourth revolute joints, the third revolute joint being rotatable about a third axis fixed with respect to the spacecraft. The first axis and the third axis are asymmetrically arranged with respect to a spacecraft coordinate system origin such that the first and third axis are at acute angles to a spacecraft pitch axis and the acute angle of the first axis is less than that of the third axis.

Abstract: A wireless communication system includes frequency reuse between terminals in common coverage regions using a multiple satellite architecture with spatial diversity. Different terminals may be associated with different ones of the satellites such that a common frequency can be reused by the different terminals. A gateway may communicate with a first satellite using a feeder beam having an overlapping geographic coverage region with a user beam used for communication between a set of user terminals and a second satellite. Spatial diversity is provided between the satellites, and the feeder beam and the user beam operate at common frequencies within the overlapping coverage region. In this manner, the bandwidth of both satellites at the common coverage region is used to increase the available capacity.

Abstract: A spacecraft includes an antenna reflector coupled with an antenna pointing mechanism (APM), a beam forming network including variable amplitude and phase (VAP) adjusting arrangements, a tracking feed that receives a beacon signal by way of the reflector, and an autotrack receiver that measures pointing errors of the reflector from the received beacon signal and outputs corresponding pointing errors to the APM controller and to a VAP element controller. The antenna reflector is illuminated by radiating feed elements configured as a phased array that produces, in a far field of the reflector, a set of user beams. The APM controller causes the APM to adjust the reflector pointing, at a frequency less than f1, to reduce the measured pointing errors. The VAP element controller adjusts pointing of the user beams by adjusting beam forming coefficients of the VAP adjusting arrangements at a second frequency greater than f1.

Abstract: Techniques for two-axis articulation of a deployed spacecraft solar array are disclosed. In one aspect, an arrangement mechanically coupling a solar array with a sidewall of a body of a spacecraft includes a proximal appendage, a distal appendage rotatably coupled with the proximal appendage by way of a hinge, and a closed cable loop (CCL) system coupled with the proximal appendage and the distal appendage. In an on-orbit configuration, a long axis of the proximal appendage defines an ? axis that is substantially orthogonal to the sidewall. The hinge includes CCL disengagement mechanism configured to de-couple the CCL system from the proximal appendage and the distal appendage and a rotation driving mechanism configured to cause the distal appendage to rotate about a ? axis when the proximal appendage is in the on-orbit configuration, the ? axis being not aligned with the ? axis.

Abstract: A spacecraft includes at least one deployable propulsion module, the propulsion module including at least one thruster fixedly disposed with respect to the propulsion module, a first arrangement for coupling the propulsion module to a first portion of the spacecraft in a first configuration and a second arrangement for coupling the propulsion module to a second portion of the spacecraft in a second configuration. The spacecraft is reconfigurable, on-orbit, from the first configuration to the second configuration. In the first configuration, the deployable propulsion module is detached from the second arrangement and the at least one thruster is oriented to produce thrust in a first direction. In the second configuration, the deployable propulsion module is detached from the first arrangement and the at least one thruster is oriented to produce thrust in a second direction, the second direction being substantially different from the first direction.

Abstract: A system described herein includes a ground based gateway subsystem configured to transmit an RF feeder uplink beam to a satellite, and a space based subsystem of the satellite configured to receive the RF feeder uplink beam and produce in dependence thereon an optical ISL beam that is transmitted to another satellite. The ground based gateway subsystem can include a ground based beamformer used to produce the RF feeder uplink beam. The optical ISL beam, produced by the space based subsystem and transmitted to the other satellite, can comprise a wavelength division multiplexed optical signal having RF frequencies within a same specified RF frequency range within which the other satellite is configured to transmit a plurality of RF service downlink beams, thereby eliminating any need for the other satellite to perform any frequency conversions when producing the plurality of RF service downlink beams in dependence on the optical ISL beam.

Abstract: A satellite communication system includes a non-geostationary satellite configured to provide a first plurality of non-articulated spot beams that comprise a Field of Regard. The satellite further configured to provide a steerable spot beam that can be steered to establish communication with a gateway outside and in front of the Field of Regard and maintain communication while the satellite and the Field of Regard moves over and past the gateway including after the gateway is outside of and behind the Field of Regard.

Abstract: Synchronization technology is implemented for a satellite communication system. Master clock information is accessed at a terrestrial location. A timing message based on the master clock information is transmitted from the terrestrial location to a satellite as the satellite is in orbit. The satellite is synchronized to the master clock based on the timing message. A beacon signal is transmitted from the satellite toward Earth. The beacon signal includes timing information. The beacon signal is received at a ground based gateway. The gateway is synchronized to the satellite based on the beacon signal. Communication is sent from the gateway to a terminal via the satellite. The communication includes timing data. The terminal is synchronized to the gateway based on the timing data.

Abstract: A spacecraft includes a structural interface adapter for mating to a launch vehicle, at least one radiator panel, at least one interior equipment panel and a 3-D truss structure. The 3-D truss structure is mechanically coupled with the structural interface adapter, the at least one radiator panel, and the at least one interior equipment panel, and at least a portion of the 3-D truss structure is disposed between the radiator panel and the interior panel.

Abstract: A wireless communication system includes frequency reuse between terminals in common coverage regions using a multiple satellite architecture with spatial diversity. Different terminals may be associated with different ones of the satellites such that a common frequency can be reused by the different terminals. A gateway may communicate with a first satellite using a feeder beam having an overlapping geographic coverage region with a user beam used for communication between a set of user terminals and a second satellite. Spatial diversity is provided between the satellites, and the feeder beam and the user beam operate at common frequencies within the overlapping coverage region. In this manner, the bandwidth of both satellites at the common coverage region is used to increase the available capacity.

Abstract: Beamforming channels of a satellite are calibrated using a low power, spread spectrum calibration signal. The power of the calibration signal is below the noise level of a user signal in an active channel, allowing channels to be calibrated while active. When calibrating the transmit side circuitry, a two-stage calibration can be used, first calibrating the output hybrid matrix, then calibrating the whole of the transmit side. To improve performance, the dwell time spend calibrating a channel can be based on the power of the user signal in the channel. A transmit probe can be used to inject a calibration signal into the receive antennae and a receive probe can be used to extract the calibration signal from the transmit antennae. To reduce frequency of calibrations, the calibrations can be based on path-to-path differences. These techniques are also applied to multiport amplifiers (MPAs).

Abstract: A satellite communication system provides for handovers between satellites and multiple gateways. Terminals communicate with a first gateway via a first satellite as beams of the first satellite traverse the region. A second gateway is in communication with the first satellite and hands over to a second satellite. The first gateway is at a first location. The second gateway is at a second location separated from the first location in the orbital direction. Terminals handover to the second satellite as beams of the second satellite begin to traverse the region, and the terminals start connecting to and communicating with the second gateway via the second satellite. After all of the terminals of the plurality of terminals handover to the second satellite, the first gateway hands over to the second satellite and then the terminals in the region communicate with the first gateway via the second satellite.

Abstract: A stationkeeping strategy for a satellite disposed in a TAP orbit includes controlling parameters of the orbit such that, for a constellation of two satellites disposed in the orbit, the constellation provides substantially continuous coverage of a polar region. The stationkeeping strategy includes one or more of: establishing an initial Right Ascension of Ascending Node (RAAN) of the operational orbit such that naturally caused orbital drift results in a mid-life RAAN of approximately 0 degrees (360 degrees); and controlling Argument of Perigee (ARGP), only indirectly, by performing orbit maintenance maneuvers only to directly control one or more of the operational orbit apogee altitude, the operational orbit perigee altitude, and inclination within a respective required range.

Abstract: A spacecraft payload subsystem includes a tracking receiver, an input multiplexer, an antenna pointing mechanism (APM) controller and a plurality of antenna reflectors. Each antenna reflector is mechanically coupled with a respective APM, and illuminated by a respective tracking feed element. Each respective tracking feed element is configured to receive an uplink beacon signal from the ground by way of one of the antenna reflectors and is coupled, by way of a respective pseudo-monopulse (PSM) coupler and the input multiplexer, to the tracking receiver. The tracking receiver is configured to receive multiplexed signals from the PSM couplers by way of the input multiplexer and output corresponding pointing error information to the APM controller. The APM controller is configured to send commands to one or more of the APMs. Each APM is configured to point a respective antenna reflector in response to the commands.