Energy efficient satellite maneuvering is described herein. One disclosed example method includes maneuvering a satellite that is in an orbit around a space body so that a principle sensitive axis of the satellite is oriented to an orbit frame plane to reduce gravity gradient torques acting upon the satellite. The orbit frame plane is based on an orbit frame vector.

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 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.

A method for controlling the orbit of a satellite in earth orbit. The orbit of the satellite is controlled by commanding, according to a maneuver plan, a propulsion system having at least one thruster and a transporter to move the propulsion system. The maneuver plan includes at least two orbit-control maneuvers. The thrust powers of the propulsion system during the two orbit control maneuvers have respective thrust directions that are not parallel in an inertial frame of reference. Each thrust power is determined to simultaneously control the inclination and the position of the orbit of the satellite as well as to form a momentum that is suitable for unloading a device for storing angular momentum of the satellite in a plane orthogonal to the direction of thrust of the thrust power.

Energy efficient satellite maneuvering is described herein. One disclosed example method includes maneuvering a satellite that is in an orbit around a space body so that a principle sensitive axis of the satellite is oriented to an orbit frame plane to reduce gravity gradient torques acting upon the satellite. The orbit frame plane is based on an orbit frame vector.

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.

Systems, methods, and apparatus for space surveillance are disclosed herein. In one or more embodiments, the disclosed method involves scanning, by at least one sensor on at least one satellite in super-geostationary earth orbit (super-GEO), a raster scan over a field of regard (FOR). In one or more embodiments, the scanning is at a variable rate, which is dependent upon a target dwell time for detecting a target of interest. In at least one embodiment, the target dwell time is a function of a characteristic brightness of the target.

A satellite system may have a constellation of communications satellites that provides services to users with electronic devices such as portable electronic devices and home and office equipment. A network operations center may use gateways to communicate with the satellite constellation. The satellite constellation may include sets of satellites with different orbits such as circular orbits with different inclinations, sets of satellites with elliptic orbits, sets of satellites with circular orbits of different altitudes including low earth orbits, medium earth orbits, and/or geosynchronous orbits, and/or sets of satellites with other orbits. The satellite orbits of the satellites in the satellite constellation may be selected to provide coverage to desired user population concentrations at different locations on the earth without using an excessive number of satellites.

An orbiting satellite can be maintained in a geosynchronous orbit (e.g., with an orbital period equal to one sidereal day) at an altitude other than 35,786 km by equipping the satellite with at least one radial thruster. Radial thrusters on the anti-Earth-facing side of the satellite allow for artificial geosynchronous orbits higher than the natural altitude, while radial thrusters on the Earth-facing side of the satellite allow for artificial geosynchronous orbits lower than the natural altitude. This allows a geosynchronous satellite to evade threats, such as orbital debris and/or hostile spacecraft, without losing signal to ground based antennas. Similar techniques can also be used for surveillance of satellites in geosynchronous orbits.

Energy efficient satellite maneuvering is described herein. One disclosed example method includes maneuvering a satellite that is in an orbit around a space body so that a principle sensitive axis of the satellite is oriented to an orbit frame plane to reduce gravity gradient torques acting upon the satellite. The orbit frame plane is based on an orbit frame vector.