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.

A three-loop inertial stabilization system with active jitter suppression and optical control to reduce line-of-sight (LOS) jitter based on platform induced motion in cantilevered gimbal systems. A first loop comprises at least one rate sensor, a Kalman state estimator, and a rate to angle module. A second loop comprises a mirror system, a focal plane and centroid processing module, an open-loop closed loop selector, a signal combiner and a loop integrator. A third loop comprises a fast steering mirror, offload module and at least one gimbal motor driver, wherein the three loops suppress the jitter of the cantilevered gimbal system.

A lunar orbiting satellite system executes orbit planning of assigning a function (positioning, communication, and flashing) to an artificial satellite (AS) depending on a relative position of the AS to the moon at a time when the moon and the AS are observed from an input point on the earth, and correcting the relative position, which changes in accordance with the moon revolution period. The system includes: a satellite orbit planner which assigns a function to each ASs forming an AS group flying around the moon depending on a relative position of each ASs to the moon at a time when the moon and ASs are observed from an input point on the earth, and set a target orbit according to the function; and a satellite controller which causes the each ASs to execute control based on the function to implement switching of the function.

A system and methods are disclosed for an upper stage space launch vehicle that uses gases from the propellant tanks to power an internal combustion engine that produces mechanical power for driving other components including a generator for generation of electrical current for operating compressors and fluid pumps and for charging batteries. These components and others comprise a thermodynamic system from which system enthalpy may be leveraged by extracting and moving heat to increase the efficient use of propellant and the longevity and performance of the launch vehicle.

An apparatus includes a satellite in the form of a plate having a thickness being smaller than a width of the satellite. The apparatus also includes a plurality of contact points distributed on a face of the satellite, allowing for one or more additional satellites to be stacked upon the satellite.

An orbit transfer method for a spacecraft using a continuous or quasi-continuous thrust propulsion, the method comprises: the acquisition, at least once in each half-revolution of the spacecraft, of measurements of its position and of its velocity; the computation of a thrust control function as a function of the measurements; and the driving of the thrust in accordance with the control law; wherein the control law is obtained from a Control-Lyapunov function using orbital parameters, preferably equinoctial, of the spacecraft, averaged over at least one half-revolution. An embedded driving system for a spacecraft for implementing such a method and a spacecraft equipped with the driving system are provided.

Attitude of a vehicle may be controlled using movable mass. The movable mass may move inside a vehicle or its outline, outside of the vehicle or its outline, inside-to-outside and/or outside-to-inside of the vehicle or its outline, or any combination thereof. The movable mass may be a solid, liquid, and/or gas. When the center-of-mass of the vehicle is moved relative to the line-of-action of applied forces such as thrust, drag, or lift, a torque can be generated for attitude control or for other purposes as a matter of design choice. In the case of external movable masses that extend from the vehicle or its outline, when operating in endoatmospheric flight, or general travel through a fluid, aerodynamic forces from the atmosphere or general fluid forces may further be leveraged to control the attitude of the vehicle (e.g., aerodynamic flaps).

A slew rate detection circuit connected to a sensor detects when an analog electrical signal from the sensor indicates a slew rate that exceeds a threshold value, and generates an interrupt electrical signal when the slew rate is detected as exceeding the threshold value. A control circuit determines a measurement value of the physical property in response to receiving the interrupt signal. The control circuit is connected to an A/D converter, which converts the analog electrical signal into a digital electrical signal, and performs a plurality of sensing system operations including determining the measurement value of the physical property as a function of the digital electrical signal.

A device for determining an attitude of a satellite is disclosed, the satellite having an attitude control system comprising a gyroscopic actuator including a flywheel mounted so as to be rotatable around an axis of rotation and carried by a gimbal articulated to rotate around an axis of rotation. The device includes an attitude sensor configured to measure the attitude of the satellite, a position sensor configured to measure the angular position of the gimbal around its axis of rotation, a speed sensor configured to measure the rotational speed of the flywheel, and a processing circuit configured to determine the attitude of the satellite by using the measurement of the angular position of the gimbal, the measurement of the rotational speed of the flywheel, and the measurement of the attitude of the satellite.

The present invention provides a method for refined attitude control based on output feedback for a flexible spacecraft. The control method comprises the following steps of: a) building a flexible spacecraft dynamical system Σ.sub.1, converting the flexible spacecraft dynamical system Σ.sub.1 into a flexible spacecraft dynamical system Σ.sub.2, and incorporating spacecraft rigid-flexible coupling dynamic disturbance into the flexible spacecraft dynamical system Σ.sub.2; b) constructing an external system Σ.sub.3, and describing the rigid-flexible coupling dynamic disturbance through the external system Σ.sub.3; c) configuring a disturbance observer for estimating the value of the rigid-flexible coupling dynamic disturbance; d) configuring a dynamic output feedback H.sub.∞ controller; e) compounding the disturbance observer in step c) with the dynamic output feedback H.sub.∞ controller in step d) to obtain a flexible spacecraft refined attitude control system Σ.sub.6; the flexible spacecraft refined attitude control system Σ.sub.6 compensating for the rigid-flexible coupling dynamic disturbance through the estimated value.