Abstract: The method and the system of this invention center around the innovative concept of an orbit-independent spacecraft comprised of a physical structure that provides multiple docking devices placed in a spatial relationship and orientation on the exterior of the spacecraft. The docking devices provide a standard interface to the spacecraft by which to attach and detach modular components (payloads). Payloads to be docked to the spacecraft have identical docking devices as part of their physical assemblies. A payload that has been launched into space is navigated towards the spacecraft using a transfer vehicle. Payload and spacecraft docking devices are brought into physical contact where internal locking mechanisms create a secure attachment of the payload to the spacecraft. Physical connections within the payload and spacecraft docking devices are made, allowing the payload to access bus capabilities such as electrical power, data communications, sensor readings, and thermal management from the spacecraft.

Abstract: A method includes: during a first time period, pumping propellant: to a set of moderator coolant channels to cool the moderator; through a set of fuel elements to heat the propellant to a first outlet temperature; out of a thrust nozzle to produce a first thrust; and locating the reflector at a first closed position to reflect neutrons toward the set of fuel elements to maintain a fission rate of the set of fuel elements above a threshold fission rate. Additionally, during a second time period: locating the reflector at a second open position to reduce the fission rate of the set of fuel elements to below the threshold fission rate; and pumping the propellant through the fuel elements to heat the propellant to a second outlet temperature less than the first outlet temperature and out of the thrust nozzle to produce a second thrust less than the first thrust.

Abstract: A node of a satellite constellation system includes a global positioning receiver configured to receive first signaling from a first plurality of non-LEO navigation satellites of a constellation of non-LEO navigation satellites in non-LEO around the earth. A transceiver is configured to send and receive inter-node communications with other nodes of the satellite constellation system. At least one processor is configured to execute operational instructions that cause the at least one processor to perform operations that include: determining a state of the node of the satellite constellation system based on applying precise point positioning (PPP) correction data to the first signaling, wherein the PPP correction data is received separately from the first signaling; and generating a navigation message based on the state of the node.

Abstract: Systems and methods for satellite Synthetic Aperture Radar (SAR) artifact suppression for enhanced three-dimensional feature extraction, change detection, and/or visualizations are described. In some aspects, the described systems and methods include a method for suppressing artifacts from complex SAR data associated with a scene. In some aspects, the described systems and methods include a method for creating a photo-realistic 3D model of a scene based on complex SAR data associated with a scene. In some aspects, the described systems and methods include a method for identifying three-dimensional (3D) features and changes in SAR imagery.

Abstract: An on-orbit recycling method for a buffer foam of a cargo spacecraft includes the following steps: mechanically cutting a shaped PU foam into foam micro-blocks, and putting the foam micro-blocks into a packaging bag for packaging, where the packaging bag is filled with a foaming adhesive; the foaming adhesive includes a component A and a component B, which are independently packaged in a two-component packaging bag; and the component A and the component B are separated by a film; and squeezing the film between the component A and the component B, such that the two components are fully mixed, foamed and expanded to finally burst the two-component packaging bag, where after the packaging bag is burst, the foaming adhesive expands into gaps of the foam micro-blocks; and in a microgravity state of space, the foaming adhesive expands and fills uniformly in all directions and fully infiltrates the foam micro-blocks.

Abstract: A ground-based node of a satellite system operates by: communicating control data with LEO navigation satellites in LEO around the earth; transmitting corrections data to the LEO navigation satellites; receiving a first collection of observations based on signaling from non-LEO navigation satellites in non-LEO around the earth, the signaling including collected observations from the non-LEO navigation satellites; receiving a second collection of observations based on navigation messages from the LEO navigation satellites, wherein the navigation messages facilitate client devices to determine their enhanced position when received in conjunction with second signaling from the non-LEO navigation satellites, and wherein the navigation messages are generated by the LEO navigation satellites in response to the corrections data; updating the corrections data based on the first collection of observations, the second collection of observations and based on telemetry data corresponding to the LEO navigation satellites

Abstract: An expendable launch vehicle is provided using pressure-fed liquid propellant fixed steering ablatively-cooled rocket engines. The vehicle is manufactured minimizing toxic or exotic metals and maximizing the use of conventional, inexpensive composites and 3D printed parts. Fuselage, fairing, stage shells, adapters, propellant tanks, and even engine combustion chambers are unified for all stages, are ablatively cooled, and, like the fairing, integral propellant tanks and adapters, are made of composites or 3D printed parts. Using non-toxic materials with non-toxic by-products, and non-toxic fabrication methods, using mostly non-metallic components allows for an environmentally neutral design.

Abstract: A ground-based node of a satellite system operates by: communicating control data with LEO navigation satellites in LEO around the earth; transmitting corrections data to the LEO navigation satellites; receiving a first collection of observations based on signaling from non-LEO navigation satellites in non-LEO around the earth, the signaling including collected observations from the non-LEO navigation satellites; receiving a second collection of observations based on navigation messages from the LEO navigation satellites, wherein the navigation messages facilitate client devices to determine their enhanced position when received in conjunction with second signaling from the non-LEO navigation satellites, and wherein the navigation messages are generated by the LEO navigation satellites in response to the corrections data; updating the corrections data based on the first collection of observations, the second collection of observations and based on telemetry data corresponding to the LEO navigation satellites

Abstract: Systems and methods for three-dimensional printing using microwave assisted deposition are disclosed herein. An example device includes a reservoir of carbonaceous nanocomposite thermoset, a microwave resonance cavity that cures the carbonaceous nanocomposite thermoset, and a sensor to measure the extrusion temperature of the resin when curing the carbonaceous nanocomposite thermoset at the point of deposition during extrusion-based 3D printing.

Abstract: A satellite is operable to generate a navigation message. Encrypted navigation message data is generated from the navigation message by applying an encryption scheme to the navigation message. An encrypted ranging signal is generated by applying the encryption scheme to a spreading code of the satellite. A secure navigation signal is generated based on modulating the encrypted navigation message data upon the encrypted ranging signal. The secure navigation signal is broadcast for receipt by at least one client device. The secure navigation signal facilitates the at least one client device to determine state data of the at least one client device by utilizing key data associated with the encryption scheme.

Abstract: A system includes a nuclear reactor having a plurality of fuel rods of radioactive decay material distributed within and embedded within a heat exchange matrix. A plurality of coolant tubes is distributed within and embedded within the heat exchange matrix, interspersed with the plurality of fuel rods. The heat exchange matrix is configured to conduct heat from the fuel rods to the coolant tubes.

Abstract: A satellite orbiting in one of a plurality of orbital planes of a satellite constellation system at an altitude range corresponding to low earth orbit includes at least one processor configured to generate satellite state data, and to generate a navigation signal based on the satellite state data. The satellite includes at least one transmitter configured to transmit the navigation signal for receipt by at least one client device on earth. Each of the plurality of orbital planes includes a corresponding one of a plurality of satellite subsets of a plurality of satellites of the satellite constellation system. Each of the plurality of orbital planes is within the altitude range, and the plurality of orbital planes includes a set of inclined orbital planes at a non-polar inclination.

Abstract: A satellite orbiting in one of a plurality of orbital planes of a satellite constellation system at an altitude range corresponding to low earth orbit includes at least one processor configured to generate satellite state data, and to generate a navigation signal based on the satellite state data. The satellite includes at least one transmitter configured to transmit the navigation signal for receipt by at least one client device on earth. Each of the plurality of orbital planes includes a corresponding one of a plurality of satellite subsets of a plurality of satellites of the satellite constellation system. Each of the plurality of orbital planes is within the altitude range, and the plurality of orbital planes includes a set of inclined orbital planes at a non-polar inclination.

Abstract: A low-earth orbit (LEO) satellite operates to: determine an orbital position of the LEO satellite based on the first signaling and based on precise point positioning (PPP) correction data associated with the constellation of non-LEO navigation satellites, wherein the PPP correction data includes orbital correction data and timing correction data associated with the constellation of non-LEO navigation satellites, and wherein the PPP correction data is received separate from the first signaling; determine, based on the inter-satellite communications, an error condition associated with one of the other LEO navigation satellites of the constellation of LEO navigation satellites; and broadcast a navigation message based on the orbital position, wherein the navigation message includes a timing signal and the orbital position associated with the LEO satellite, correction data associated with the constellation of non-LEO navigation satellites, and an alert signal that indicates the error condition associated with one

Abstract: A flat panel antenna fed by a planar feed array and steered by varactors performs the function of a single beam phased array antenna. This flat panel antenna has a planar array to passively amplify radio frequency (RF) signals, and a transmitarray metasurface having an array of unit cells to steer the antenna's main beam. It uses varactors to dynamically control the phase shift for each unit cell.

Abstract: A satellite orbiting in one of a plurality of orbital planes of a satellite constellation system at an altitude range corresponding to low earth orbit includes at least one processor configured to generate satellite state data, and to generate a navigation signal based on the satellite state data. The satellite includes at least one transmitter configured to transmit the navigation signal for receipt by at least one client device on earth. Each of the plurality of orbital planes includes a corresponding one of a plurality of satellite subsets of a plurality of satellites of the satellite constellation system. Each of the plurality of orbital planes is within the altitude range, and the plurality of orbital planes includes a set of inclined orbital planes at a non-polar inclination.

Abstract: In accordance with at least one aspect of this disclosure, a method includes flushing a cell stack for a predetermined amount of time as a function of an amount of combustible gas remaining in the cell stack. The method also includes operating a cell stack for a predetermined amount of time, then shutting down the cell stack and ceasing operation of the cell stack for a predetermined amount of time. Flushing occurs after shutting down a cell stack power supply. The method further includes restarting operation of the cell stack after flushing.

Abstract: A low-earth orbit (LEO) satellite operates to: determine an orbital position of the LEO satellite based on the first signaling and based on precise point positioning (PPP) correction data associated with the constellation of non-LEO navigation satellites, wherein the PPP correction data includes orbital correction data and timing correction data associated with the constellation of non-LEO navigation satellites, and wherein the PPP correction data is received separate from the first signaling; determine, based on the inter-satellite communications, an error condition associated with one of the other LEO navigation satellites of the constellation of LEO navigation satellites; and broadcast a navigation message based on the orbital position, wherein the navigation message includes a timing signal and the orbital position associated with the LEO satellite, correction data associated with the constellation of non-LEO navigation satellites, and an alert signal that indicates the error condition associated with one

Abstract: In accordance with at least one aspect of this disclosure, a life support system (LSS) for a spacecraft includes a gas accumulator configured to store a gas, the gas accumulator including a non-metallic inner lining. A fluid processor is fluidly connected to the gas accumulator configured to produce one or more life sustaining fluids from at least the gas. A supply conduit can be fluidly connected to the fluid processor configured to supply the one or more life sustaining fluids to one or more portions of the spacecraft.

Abstract: A system includes an oxidative combustion reactor configured to receive solid organic waste and O2, and to output a combined stream of H2O and CO2. A separator is configured to receive the combined stream of H2O and CO2 from the combustion reactor and to separately output a stream of CO2 and a stream of H2O. A Sabatier reactor is operatively connected to receive CO2 from the separator and to receive H2 from an H2 source, and to output gaseous CH4.