Disclosed are an attitude estimation method, a terminal, a system and a computer-readable storage medium. For the problem of attitude and sensor bias estimation, a cascade solution method is provided. The first part of the cascade is a Kalman filter applied to an LTV system, and the second part of the cascade is a nonlinear attitude observer built in SO(3). In the estimation process, only one constant inertial reference vector needs to be measured explicitly in body-fixed coordinates, and the complexity of the attitude estimation algorithm is greatly simplified by exploiting the geometric relationship between the inertial reference vector and the Earth angular velocity vector. At the same time, the time-varying characteristics of the implemented Kalman filter help to avoid the tedious empirical gain adjustment process that often relies on sets of piecewise constant gains, to improve the convergence speed of the algorithm.

A control system configured to execute a safing mode sequence for a spacecraft is disclosed. The control system includes one or more star trackers that each include a field of view to capture light from a plurality of space objects surrounding the celestial body. The control system also includes one or more actuators, one or more processors in electronic communication with the one or more actuators, and a memory coupled to the one or more processors. The memory stores data into a database and program code that, when executed by the one or more processors, causes the control system to determine a current attitude of the spacecraft, and re-orient the spacecraft from a current attitude into a momentum neutral attitude.

A method and apparatus for estimating gyro scale factor during normal spacecraft operations, using small attitude motions that are compliant with mission pointing accuracy and stability requirements and a signal processing method that specifically detects the intentionally induced motions. This process increases operational availability by avoiding the need to take the spacecraft offline for large calibration maneuvers.

The disclosure relates to a method and apparatus of rotating mass attitude control. The method and apparatus entails rotating a mass to generate thrust. Varying the speed and direction of rotation provides some control of the magnitude and direction of the thrust generated. The method and apparatus of the invention pertinent to an attitude control system for spacecrafts or astromotive vehicles under conditions of zero to low gravity and atmosphere.

A method for determining the position of a spacecraft in space, includes cyclically÷ repeating steps of capturing distorted star images; processing the distorted star images to form distorted star group data; storing the distorted star group data; determining a current rotation rate by comparing the distorted star group data of two consecutive cycles; transmitting the current rotation rate to a position control system; and/or the following steps are carried out: processing the distorted star images of a current cycle to form rectified star group data; determining position information by matching the rectified star group data with star group catalog data which is carried along; transmitting the position information to the position control system. A method for determining the position of a spacecraft in space, taking into account known system parameters of an optical system, includes: coding star group catalog data with n = 3...4 stars [x.sub.n, y.sub.n, z.sub.n], which are visible in an image field, into representative focal-plane coordinates; forming a scaling-, translation-, and rotation-invariant star group code on the basis of [xPiX,yPiX]n; or coding star group catalog data with n = 3...4 stars [x.sub.n,y.sub.n, z.sub.n], which are visible in an image field, into representative tangent and/or angular coordinates [tan(a),tan(β)].sub.n. The invention further relates to a device for carrying out such methods and to a computer program product for carrying out such methods.

A satellite module for attitude determination includes a containment body comprising at least one data acquisition board and a connection interface, at least one first-type sensor selected from a sun sensor, an earth sensor, a stellar sensor, a horizon sensor, in communication with the data acquisition board and at least one second-type sensor, different from the first type, selected from a sun sensor, an earth sensor, a stellar sensor, a horizon sensor, and in communication with the data acquisition board. The connection interface may be mounted on a first face of the containment body, the first-type sensor may be mounted on a second face of the containment body, and the second-type sensor may be mounted on a third face of the containment body.

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.

Deployable reflectors and antennas and spacecraft using such reflectors are disclosed. An example disclosed reflector includes: a hub having a cross-section formed in a circular, elliptical or polygonal shape; a plurality of ribs, each rib having an inner side surface facing an outer peripheral side of the hub when folded, and an outer side surface that is a surface opposite to the inner side surface, the plurality of ribs being folded to be wound around an outer periphery of the hub such that the inner side surface of each rib and the outer side surface of its adjacent rib partially face each other or the outer side surface of each rib and the inner side surface of its adjacent rib partially face each other, each rib being deployed in a parabolic shape; and a sheet installed across each of the plurality of ribs and capable of reflecting radio waves.

Techniques for improving the quality of images captured by a remote sensing overhead platform such as a satellite. Sensor shifting is employed in an open-loop fashion to compensate for relative motion of the remote sensing overhead platform to the Earth. Control signals are generated for the sensor shift mechanism by an orbital motion compensation calculation that uses the predicted ephemeris (including orbit dynamics) and image geometry (overhead platform to target). Optionally, the calculation may use attitude and rate errors that are determined from on-board sensors.

Systems and method for controlling the attitude maneuvers of a spacecraft in space are provided. The method automatically generates optimal trajectories in real-time to guide a spacecraft, providing a much more robust and efficient method than predefined trajectories, to model errors or disturbances. These methods do not rely in predefined trajectories and their associated feed-forward term. The systems comprise sensors, attitude control mechanisms, and a control module to orient the spacecraft in real-time, such that the spacecraft reaches a desired target attitude following an optimal path in the state space and is locally and asymptotically stable.