Abstract: Techniques are disclosed for providing a redundant telemetry transmission path on a spacecraft. The spacecraft includes a telemetry (TLM) transmitter having a modulation input coupled by a commandable switch with a signal source. The TLM transmitter is configured to receive an output from the signal source when the commandable switch is closed. The computer is configured to encode TLM data bits onto a TLM downlink signal by actuating the commandable switch, such that a signal from the signal source received by the TLM transmitter is temporally varied between an on condition and an off condition.

Abstract: Cloud mask image data is obtained by a secondary imaging payload disposed on a communications or broadcast satellite operating in geosynchronous orbit. The obtained cloud mask image data is provisioned for use, in near real time, by one or more low earth orbit imaging satellite systems. Provisioning the obtained cloud mask image data may include collecting the data on the ground and making it available to one or more operators of the one or more LEO imaging satellite systems and/or transmitting the data from the communications or broadcast satellite to at least one spacecraft in the one or more LEO imaging satellite systems.

Abstract: A spacecraft includes a 3-D closed truss structure including at least four coupling nodes and at least six strut elements, attached together by a plurality of joints, each coupling node including at least two legs, each strut element disposed between and attached with a respective pair of the plurality of coupling nodes. Each coupling node is attached, at respective ones of the plurality of joints, with at least two strut elements. Each strut element is attached at a first end with a first leg of a first coupling node and is attached at a second end with a second leg of a second coupling node, the first leg being substantially longer than the second leg.

Abstract: A constellation of non-geosynchronous satellites are in a common orbit. Each time one of the satellites is at a trigger location, a new rolling wave of handovers is started that includes performing handovers of a group of dependent spot beams between adjacent satellites in sequence for pairs of adjacent satellites in a single direction around the orbit.

Abstract: A communication platform (e.g., a flexible satellite) includes electrical to optical converters configured to convert input electrical signals to input optical signals, an optical switching network connected to the electrical to optical converters that choose which input optical signals to route to which output beams, tunable optical filters (connected to the switching network) that are configured to select programmable sub-bands of the input optical signals to create output optical signals, and optical to electrical converters (connected to the tunable optical filters) that are configured to convert the output optical signals to output electrical signals for the output beams.

Abstract: A launch vehicle includes an upper stage and an integral fairing. In a launch configuration, the integral fairing is configured to enclose, between an aft portion and a forward portion, one or more payloads. The integral fairing includes a mechanical attachment with the upper stage proximal to the aft portion, and a nose cap proximal to the forward portion and a passive venting arrangement that equalizes pressures internal and external to the integral fairing. The integral fairing is configured to permit deployment of at least one payload, while avoiding: (i) separation of the integral fairing into two or more parts, (ii) separation of the integral fairing from the upper stage, and (iii) articulation of the mechanical attachment. The upper stage may provide single stage to orbit capability.

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 wireless communication platform utilizes flexible bandwidth assignment to re-allocate bandwidth between spot beams. The platform may assign a first combination of frequency and polarization (FP) to a first spot beam and a second combination of frequency and polarization to a second spot beam that is adjacent and at least partially overlapping the first spot beam. The platform may assign to the first spot beam a reserved combination of frequency and polarization during a first time period, and at second time, assign the reserved combination to the second spot beam. The platform may also assign the reserved combination simultaneously to adjacent spot beams by managing user of the reserved combination by geographically isolated terminals in the spot beams. The platform may further assign different portions of the reserved combination to adjacent spot beams without geographical limitations.

Abstract: Techniques for deorbiting a satellite include executing an orbit transfer maneuver that transfers the satellite from an operational orbit to an interim orbit. The operational orbit is substantially geosynchronous and has (i) an inclination of greater than 70 degrees; (ii) a nominal eccentricity in the range of 0.25 to 0.5; (iii) an argument of perigee of approximately 90 or approximately 270 degrees; (iv) a right ascension of ascending node of approximately 0; and (v) an operational orbit apogee altitude. The interim orbit has an initial second apogee altitude that is at least 4500 km higher than the first apogee altitude, and the interim orbit naturally decays, subsequent to the orbit transfer maneuver, such that the satellite will reenter Earth's atmosphere no longer than 25 years after completion of the orbit transfer maneuver.

Abstract: A satellite network comprises networks nodes including multiple satellites, multiple gateways, additional servers and a mobile vehicle (e.g., an aircraft). All of (or a subset) of the network nodes include switches. The network implements a software defined network that includes a mobility manager as part of the management plane, a network controller as part of the control plane, and the switches on the network nodes as the data plane. In one embodiment, the switches communicate using an Open Flow communications protocol and make routing decisions based on flow tables. The mobility manager communicates with, and manages, the switches via the network controller. The mobility manager proactively generate updates to flow tables based on satellite ephemeris data for the multiple satellites and itinerary data for the aircraft, and pushes the updates to the switches in response to determining that the aircraft needs to be handed off between satellites.

Abstract: A spacecraft includes a first deployable module and a second deployable module and is reconfigurable from a launch configuration to an on-orbit configuration. In the launch configuration, the first deployable module is adjacent to the second deployable module. The first deployable module includes a first solar array, the first solar array being rotatable, in the on-orbit configuration, about a first axis of rotation, and the second deployable module includes a second solar array, the second solar array being rotatable, in the on-orbit configuration, about a second axis of rotation, the second axis of rotation being separated by a substantial distance from the second axis of rotation.

Abstract: A power splitting (or combining) arrangement includes a waveguide having a plurality of output (or input) ports and an input (or output) port configured to receive (or transmit) electromagnetic waves having a frequency in a designated frequency band. Each output (or input) port is configured to electrically couple with an input (or output) terminal of a corresponding one of a plurality of active devices. Each output (or input) port has a respective output impedance associated with the frequency band. The power splitting (or combining) arrangement is configured such that the respective output (or input) impedance of each output (or input) port substantially matches an input (or output) impedance of the corresponding one of the plurality of active devices.

Abstract: A satellite communication system comprises a satellite configured to provide a plurality of spot beams adapted for communication using time domain beam hopping to switch throughput among spot beams of the plurality of spot beams. The plurality of spot beams includes a first spot beam that illuminates and communicates with a first gateway and a first set of subscriber terminals. The satellite is configured to implement a beam hopping plan that during a hopping period provides throughput to the first spot beam for an aggregated time duration based on bandwidth assignments to the first gateway and the first set of subscriber terminals.

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: 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: 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: 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.