The purpose is to easily achieve verification of an integrated attitude angle based on an inertial sensor. An attitude angle calculating device may include an integrated attitude angle calculating module, a reverse-calculated value calculating module, a reference value calculating module, and a determining module. The integrated attitude angle calculating module may calculate an integrated attitude angle using an output of the inertial sensor and a positioning signal. The reverse-calculated value calculating module may reverse calculate, using the integrated attitude angle, a physical quantity obtained based on the positioning signal that is used for calculating the integrated attitude angle. The reference value calculating module may calculate a reference physical quantity corresponding to the reverse-calculated physical quantity, based on an observation value of the positioning signal. The determining module may determine whether to reset the calculation of the integrated attitude angle by using the reverse-calculated physical quantity and the reference physical quantity.

A control system for controlling an operation of a spacecraft. A model predictive controller (MPC) produces a solution for controlling thrusters of the spacecraft. The MPC optimizes a cost function over a finite receding horizon using a model of dynamics of the spacecraft effecting a pose of the spacecraft and a model of dynamics of momentum exchange devices of the spacecraft effecting an orientation of the spacecraft. The optimization is subject to hard and soft constraints on angles of thrusts generated by thrusters. Further, the hard constraints require the angles of thrusts in the solution to fall within a predetermined range defined by the hard constraints. The soft constraints penalize the solution for deviation of the angles of thrusts from nominal angles corresponding to a torque-free thrust passing through the center of the mass of the spacecraft. A thruster controller operates the thrusters according to the solution of the MPC.

A control system for reducing disturbance torque of a spacecraft is disclosed. The spacecraft revolves around a celestial body surrounded by an atmosphere. The control system includes processors in electronic communication with one or more actuators and a memory. The memory stores data into a database and program code that, when executed by the one or more processors, causes the control system to instruct the spacecraft to enter a safing mode. In response to entering the safing mode, the control system instructs the one or more actuators to align a principal axis of the spacecraft with a vector that is normal to the orbit around the celestial body. The control system also instructs the actuators to rotate the spacecraft about the principal axis, where a rotational orientation of the spacecraft relative to the celestial body is shifted by about one-half a rotation about the principal axis.

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 constellation of satellites includes a first plurality of satellites orbiting at a first inclination, wherein the first plurality of satellites are each in a discrete planar orbit to form a first snake of satellites, the first snake of satellites including adjacent satellites in adjacent orbits having adjacent RAAN (Right Ascension of the Ascending Node).

Provided are an earth satellite attitude data fusion system and method, applicable to an earth satellite space environment to estimate attitude data of a satellite. When the earth satellite attitude data fusion system of the present invention is used to perform the earth satellite attitude data fusion method, the first step is to perform a body rates/quaternion attitude data processing operation. Then, the next step is to perform an attitude/rates data fusion processing operation, wherein an attitude data fusion algorithm module receives a first IAE result data from a first EKF, and a second IAE result data from a second EKF, and performs an attitude/rates data fusion algorithm in a subsystem level to evaluate an attitude estimation IAE performance based on the first IAE result data, and the second IAE result data.

A satellite comprises thrusters disposed with the firing directions each facing away from the mass center of satellite and different from each other. A control amount calculator calculates control amounts of the mean orbital elements from the mean orbital elements and the temporal change rates of the mean orbital elements set by an orbit determiner, and the target values. A distributor calculates firing timings and firing amounts of the thrusters for realizing the control amounts of the mean orbital elements by expressing a motion of satellite with orbital elements, solving an equation taking into account coupling of an out-of-plane motion and an in-plane motion due to thruster disposition angles and thruster firing amounts at multiple times, and combining one or more thruster firings controlling mainly an out-of-the-orbit-plane direction and one or more thruster firings controlling mainly an in-the-orbit-plane direction.

A dipole cancellation system and method may include a plurality of magnetometers for measuring a device magnetic field associated with a plurality of device coils generating a device magnetic field having a primary magnetic dipole moment. A compensating coil carrying a compensating current running a first direction that generates a compensating magnetic field having a compensating magnetic dipole moment. The compensating coil may be positioned and the first current may be selected so that the compensating magnetic dipole moment completely cancels the primary magnetic dipole moment. A method may use the system to stabilize a spacecraft by calculating an estimated torque of the spacecraft, receiving a value for an external magnetic field, receiving a value for a device magnetic field, and calculating and applying a compensating current may be then applied to the compensating coil to cancel the primary magnetic dipole moment, wherein the spacecraft is stabilized.

Technique for altering a client spacecraft's rotational rate including the precise positioning of a servicing spacecraft in close proximity of a client spacecraft, alignment of a fluid release output device on the servicing spacecraft that imparts a force on the client spacecraft by means of fluid release, and subsequent use of the fluid release output device to mitigate tumbling of the client spacecraft. This allows the servicing spacecraft to slow the rotation of a tumbling client spacecraft in order to perform additional servicing operations.

A spacecraft including: an engine; a thrust vector control device controlling a thrust vector as a direction of a thrust acting on the spacecraft; and a main control device configured to acquire state quantities of the spacecraft in a powered descending in which the spacecraft is guided to a target point while the engine generates the thrust, and generate a throttling command by which combustion of the engine is controlled and an operation command by which the thrust vector control device is operated. The state quantities contain a first acceleration parameter and a second acceleration parameter. The first and second acceleration parameters are calculated as coefficients A and B obtained by fitting based on acceleration of the spacecraft detected at each time of past, supposing the following equation is satisfied between a reciprocal number 1/a of the acceleration a of the spacecraft and time t:

1/a=At+B(1).