Abstract: A satellite communications system provides for handovers between spot beams, including communicating (at a ground based terminal) with a non-geostationary satellite constellation using a first spot beam of the non-geostationary satellite constellation and a first beam hopping plan. The ground based terminal changes the communicating with the non-geostationary satellite constellation to use a second spot beam of the non-geostationary satellite constellation and a second beam hopping plan.

Abstract: A non-geostationary satellite is configured to provide a plurality of spot beams that implement a first frequency plan at Earth's Equator and a second frequency plan away from Earth's Equator. The second frequency plan is different than the first frequency plan. In one embodiment, the non-geostationary satellite is part of a constellation of non-geostationary satellites, with each of the satellites providing spot beams that implement a first frequency plan at Earth's Equator and implement a second frequency plan away from Earth's Equator as the satellites travel in orbit around Earth.

Abstract: Design of a 3-D truss structure, including a plurality of coupling nodes and a plurality of struts, is optimized by performing a quantitative optimization of an objective function corresponding to a figure of merit of the design. The quantitative optimization includes: generating a finite element analysis model, the analysis model a 3-D lattice mesh of strut-like finite elements; computing, with the finite element analysis model, a value for the objective function; and optimizing the objective function by executing at least two cycles of an optimization loop. The optimization loop includes a) computing a respective parameter of each strut-like finite element; b) deleting, from the finite element analysis model, selected finite elements for which a resulting mechanical property is less than a threshold; (c) computing an updated value for the objective function; and repeating the optimization loop until the objective function is within a desired tolerance of the specified value.

Abstract: This disclosure provides systems, methods and apparatus for implementing a non-blocking switch matrix. In one aspect, a switch matrix can include an arrangement of C-switches. Each of the C-switches can be configured to switch between two positions to couple between different channels. The C-switches can be arranged in the switch matrix as to provide non-blocking functionality such that each of the inputs of the switch matrix is routed to an output of the switch matrix in any combination of the configurations of the C-switches.

Abstract: A satellite communication system comprises one or more non-geostationary satellites. Each satellite is configured to provide a plurality of spot beams using time domain beam hopping among the spot beams. The spot beams are divided into hopping groups and each satellite is configured to switch throughput and power among spot beams in a same hopping group at intervals of an epoch over a hopping period according to a hopping plan. Each satellite is configured to receive, change and implement the hopping plan in orbit while the satellite moves in relation to a fixed geographic coverage region. The satellites are programmable to assign any combination of epochs in a hopping plan among spot beams of a same hopping group and to route throughput between spot beams.

Abstract: Waveguide hinges are provided that allow for a substantially continuous RF waveguide to be formed through the hinge when the hinge elements are in a particular relative rotational configuration with respect to one another; the substantially continuous RF waveguide is not formed when the hinge elements are in various other relative rotational configurations. Such waveguide hinges allow for waveguide elements to be repositioned during periods when RF energy is not being transmitted.

Abstract: A photovoltaic solar cell, including an N-side layer proximate to a first planar surface and a P-side layer proximate to a second planar surface that is opposite to the first planar surface, is formed from a circular wafer substrate. An N-side conductive contact is electrically coupled with the N-side layer, and a P-side conductive contact electrically coupled with the P-side layer. The P-side conductive contact and the N-side conductive contact are each disposed proximate to the first planar surface, the circular wafer substrate includes an edge exclusion zone, and the P-side contact is disposed within or proximate to the edge exclusion zone.

Abstract: A method of metallizing a surface of a structure, and in some embodiments a mirror produced by such method, by the steps of providing a composite support structure; providing a release liner including a metallic layer having a thickness between 1 and 5 microns on a surface thereof; situating the release liner against the surface of the composite support structure so that the metallic layer of the release liner is placed in direct, physical contact with the surface of the support structure; and removing the release liner so that the metallic layer remains attached to the surface of the support structure.

Abstract: A spacecraft includes an aft surface, a forward surface and a main body structure disposed therebetween, a stowage and deployment arrangement (SDA) joined to the main body structure by a first mechanical coupling, and an antenna that includes a respective feed element and a rigid antenna reflector coupled with the main body by way of the SDA. The feed element is joined to the main body structure by a second, different, mechanical coupling. The spacecraft is reconfigurable from a launch configuration, with the reflector is disposed forward of the forward surface, with its aperture plane substantially parallel to the forward surface, to an on-orbit configuration. The SDA repositions the reflector to a second position corresponding to the on-orbit configuration. In the second position, the reflector is disposed, Earth facing, substantially aft of the forward surface and outboard of the main body structure and is illuminated by the respective feed element.

Abstract: A heat transfer interface is provided for radio-frequency resonator cavity filters used in vacuum environments such as are encountered by spacecraft and satellites. The heat transfer interface may include a thermally conductive structure that encircles or partially encircles a tubular structure of the resonator cavity filter and heat transfer legs that extend from positions that are on opposite sides of the thermally conductive structure and at approximately the same distance from a support surface to the support surface. The heat transfer legs and the thermally conductive structure may be made from a material or materials having a thermal conductivity of 350 W/(m·K) or greater.

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: This disclosure provides systems, methods and apparatus for multi-channel satellite calibration. In one aspect, a calibration system can provide a transmit calibration signal based on a reference calibration signal to a satellite. The satellite can transmit back a receive calibration signal that can be obtained by the calibration system. Sub-carriers of the receive calibration signal can be compared with sub-carriers of the reference signal to determine adjustments to transmission properties of antennas of the satellite.

Abstract: A spacecraft communications payload includes a beam forming network (BFN), wherein the BFN includes a first feed waveguide and a first set of branch waveguides, each branch waveguide in the first set operating in a frequency band having a characteristic waveguide wavelength ?g1. A proximal portion of the first set of branch waveguides is communicatively coupled with the first feed waveguide. A distal portion of the first set of branch waveguides is communicatively coupled by way of an array of slots with a plurality of radiating elements. A separation distance between adjacent slots in the array is approximately equal to ?g, and the array of slots is configured as a honeycomb-like triaxial lattice. In some implementations, a compact BFN may be configured to simultaneously operate at two different polarizations (“dual-polarized”) and/or frequency bands (“dual-band”).

Abstract: A spacecraft includes a payload subsystem including a digital channelizer. The digital channelizer provides at least a portion of spacecraft command or telemetry functionality. The spacecraft may optionally also include a telemetry and command (T&C) subsystem, the T&C subsystem including one or more of a command receiver, a command decoder, a telemetry encoder and a telemetry transmitter. The digital channelizer may be communicatively coupled with at least one of the command receiver, the command decoder, the telemetry transmitter and the telemetry encoder.

Abstract: An apparatus for launching, recovering, transporting, and storing vehicles is disclosed. The apparatus stabilizes the vehicle while it is in operation or inactive and has a frame connected to at least one stabilizer. In certain configurations, the apparatus stabilizes the vehicle without using the vehicle's onboard landing gear.

Abstract: The sublimation capability of a porous metal plate used in a sublimator is maintained by heating the porous metal plate at an elevated temperature in a flowing stream of oxygen for an extended period of time to form an oxidized surface. A short chain molecule, such as citric acid, is attached to the oxidized surface having multiple functional carboxylate groups and no hydrophobic tail.

Abstract: An orthomode transducer (OMT) configured as a compact three port septum polarizer waveguide where one of the three ports is configured to propagate linear orthogonally polarized signals, and an edge of the septum facing that port has a profile including three or more segments with respective facing edges spaced at diverse respective distances from the one of the three ports that is configured to propagate linear orthogonally polarized signals. The three or more segments include one or both of a notch and a protrusion.

Abstract: This disclosure provides systems, methods and apparatus for digital beamforming. In one aspect, a subsystem of a spacecraft can include multipliers and a data distribution network including adders to provide beamformed signals.

Abstract: A spacecraft operating in a low earth orbit having an altitude in the range of 160 to 800 km has a main body that includes heat dissipating electrical equipment and an earth-facing payload. Control surfaces on the spacecraft are articulated so as to: provide three-axis attitude control to the spacecraft main body using aerodynamic drag effects, such that the earth-facing payload is maintained in a selected orientation with respect to the earth; and control one or both of orbit altitude and period by articulating the control surfaces so as to regulate an amount of aerodynamic drag. The control surfaces include a first control surface disposed, in an on-orbit configuration, on a boom, the boom being mechanically coupled with the main body, and with one or both of a solar array electrically coupled with the electrical equipment and a thermal radiating array thermally coupled with the electrical equipment.

Abstract: Described herein are ground based subsystems, and related methods, for use in transmitting an optical feeder uplink beam to a satellite that is configured to receive the optical feeder uplink beam and in dependence thereon produce and transmit a plurality of RF service downlink beams within a specified RF frequency range to service terminals. Also described herein are space based subsystems of a satellite, and related methods, for use in transmitting a plurality of RF service downlink beams within a specified RF frequency range to service terminals. Beneficially certain embodiments eliminate the satellite to perform any RF frequency conversions upstream of a channelizer of the space based forward link subsystem on the satellite. Also described herein is space segment return link equipment, and related methods, for use in transmitting an optical feeder downlink beam to a ground based subsystem, as well as ground based return link equipment thereof.