Abstract: Spacecraft propulsion systems and methods featuring a first storage tank containing a metallic propellant and a second storage tank containing a non-metallic propellant are provided. A selected one of the metallic propellant and the non-metallic propellant is supplied to an electric propulsion thruster, depending on an operational mode of the spacecraft. The metallic propellant is stored at a relatively high density, while the non-metallic propellant is stored at a lower density than the metallic propellant. Moreover, the non-metallic propellant is preferably utilized to produce thrust through the electric propulsion thruster during operational maneuvers, while the metallic propellant is reserved for producing thrust through the electric propulsion thruster during end-of-life, such as deorbiting, maneuvers.

Abstract: Systems and methods for refueling a chemical propulsion system are provided. The systems can include multiple pressurant reservoirs to supply pressure to one or more fuel tanks. During a refueling operation, pressurant is released, fuel is added to the fuel tank, and then the fuel tank is repressurized using pressurant from a secondary pressurant tank. In other configurations, during a refueling operation pressurant is cooled to depressurize the fuel tank, fuel is added to the fuel tank, and then the pressurant is heated to repressurize the fuel tank. The systems and methods can be used to refuel operationally deployed space craft.

Abstract: Chemical propellant storage and supply systems and methods for use on spacecraft are provided. The systems and methods include a fluid pump for moving chemical propellant within the system at selected pressures. This can include operating the fluid pump to supply propellant to a thruster system at a selected pressure. A fuel tank can be refilled by connecting a propellant resupply source to the system, and operating the fluid pump to move propellant from the propellant resupply source to the fuel tank. In a system with multiple fuel tanks, the fluid pump can be operated to move propellant from a donor fuel tank to a recipient fuel tank. The chemical propellant can be stored in one or more fuel tanks at a relatively low pressure. In addition, the chemical propellant is not pressurized by a gaseous pressurant while it is stored in the fuel tank.

Abstract: Integrated chemical propellant and cold gas propulsion systems and methods are provided. A storage or fuel tank containing the chemical propellant is pressurized by a pressurant. The chemical propellant is selective passed to a propellant thruster through a first port of the storage tank and a propellant valve. The pressurant is selectively passed to a cold gas thruster through a second port of the storage tank and a cold gas valve. In addition, a pressurant tank can be provided. Pressurant contained within the pressurant tank can be selectively placed in communication with the pressurant contained within the storage tank via a pressurant valve, or can be selectively passed to the cold gas thruster through the cold gas thruster valve. Systems can also include bi-propellant thrusters, with a first and second chemical compounds and volumes of pressurant stored in first and second storage tanks respectively.

Abstract: Phase correction systems and methods capable of operating in a deployed antenna system are provided. The phase correction system includes a signal generator and a signal coupler. The signal coupler injects a signal at an end of a signal line adjacent an antenna element. Changes in an effective length of the signal line can be detected at a controller that monitors characteristics of the injected signal after it has passed through the signal line. The system can adapt to detected changes in the electrical length by controlling an adjustable phase shifter provided in line with the signal line or by applying suitable post-processing.