A reconfigurable power processing unit for a spacecraft including a plurality of power modules. Each of the power modules includes a first power source and a second power source. The first power source and the second power source are configured to be in series in a first state and in parallel in a second state. A plurality of contactors connect each power module to at least one of another power module in the plurality of power modules and a power processing output and are configured to control the state of the power modules.

Bi-modal propulsion systems and related methods are generally described. In some embodiments, a bi-modal propulsion system may employ a single propellant for both chemical thruster(s), operating at elevated pressures, and electrical thruster(s) (e.g., electro spray thruster), operating at reduced pressures. The propellant pressure may be reduced to a desired operational range of the electrical thruster(s) using any appropriate construction including, for example, capillaries configured to reduce the pressure of the propellant to an operational range of the electrical thruster(s). In some embodiments, the reduced pressure of the propellant may be lower than a vapor pressure of at least one volatile component of the propellant, leading to the formation of bubbles within the propellant line. The presence of alternating gas and liquid phases along a flow path between a propellant tank and the electrical thruster(s) may help to electrically insulate the electrical thruster from the rest of the system.

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.

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.

An artificial satellite (100) includes two pointing mechanisms (110, 120). The pointing mechanisms respectively include main body side gimbals (111, 121), deployed booms (112, 122), thruster side gimbals (113, 114), and thruster groups (115, 125). The main body side gimbal connects the deployed boom to a satellite main body (130) and adjusts a direction of the deployed boom. The thruster side gimbal connects the thruster to the deployed boom and adjusts the direction of the thruster. Each gimbal is a two-axis gimbal.

A spacecraft propulsion system includes at least one chemical thruster operable with a liquid propellant, at least one electric thruster operable with an inert gas, and a first quantity n of pressurant tanks, each of the n pressurant tanks having a substantially identical volume. The propulsion system results from assembling a plurality of subassemblies, such that a first selectable number e of the first quantity of pressurant tanks are manifolded together with the at least one electric thruster, and a second selectable number c of the first quantity of pressurant tanks are manifolded together with the at least one chemical thruster. The first selectable number e is an integer in the inclusive range of 1 to n, and c=n?e.

In an example, a method includes interacting electric fields from charges in conductors in different inertial reference frames to effect motion. The example method implements the mathematical framework that divides electric fields from charges in different inertial reference frames into separate electric field equations in electrically isolated conductors. The example method may implement the interaction of these electric fields to produce a force on an assembly that can, by way of illustration, propel a spacecraft using electricity without other propellant(s).

In an example, a method includes interacting electric fields from charges in conductors in different inertial reference frames to effect motion. The example method implements the mathematical framework that divides electric fields from charges in different inertial reference frames into separate electric field equations in electrically isolated conductors. The example method may implement the interaction of these electric fields to produce a force on an assembly that can, by way of illustration, propel a spacecraft using electricity without other propellant(s).

A constellation of Earth-orbiting spacecraft includes a first spacecraft disposed in a first orbit, a second spacecraft disposed in a second orbit, and a third spacecraft disposed in a third orbit. Each of the first orbit, the second orbit and the third orbit is substantially circular with a radius of approximately 42,164 km, and has a specified inclination with respect to the equator within a range of 5? to 20?. The first orbit has a first right ascension of ascending node RAAN1, the second orbit has a second RAAN (RAAN2) approximately equal to RAAN1+120?, and the third orbit has a third RAAN (RAAN3) approximately equal to RAAN1+240?. A fourth spacecraft is disposed in a fourth orbit that has a period of approximately one sidereal day, an inclination of less than 2?, a perigee altitude of at least 8000 km, and an eccentricity between approximately 0.4 and 0.66.

In an example, a method includes interacting electric fields from charges in conductors in different inertial reference frames to effect motion. The example method implements the mathematical framework that divides electric fields from charges in different inertial reference frames into separate electric field equations in electrically isolated conductors. The example method may implement the interaction of these electric fields to produce a force on an assembly that can, by way of illustration, propel a spacecraft using electricity without other propellant(s).