Abstract: A projectile intended for damping a spacecraft (100) comprising a main body (110) and active attitude control means (150) comprises a harpoon and is intended to equip a space delivery vehicle to be projected towards the spacecraft. It comprises a passive damper (200) mounted such that it is fixed on the harpoon and suitable for generating, in cooperation with the Earth's magnetic field, a damping torque. That passive damper (200) comprises an outer enclosure (210) and an inner body (220) configured such that: the inner body, permanently magnetized, is positioned inside the outer enclosure and is capable of moving in rotation about at least one axis of rotation, the outer enclosure and the inner body comprise respectively an inner surface and an outer surface, separated by means of a viscous fluid, the outer enclosure is fixed to the main body of the spacecraft for rotation therewith once the harpoon is secured to the main body.

Abstract: A projectile intended for damping a spacecraft (100) comprising a main body (110) and active attitude control means (150) comprises a harpoon and is intended to equip a space delivery vehicle to be projected towards the spacecraft. It comprises a passive damper (200) mounted such that it is fixed on the harpoon and suitable for generating, in cooperation with the Earth's magnetic field, a damping torque. That passive damper (200) comprises an outer enclosure (210) and an inner body (220) configured such that: the inner body, permanently magnetized, is positioned inside the outer enclosure and is capable of moving in rotation about at least one axis of rotation, the outer enclosure and the inner body comprise respectively an inner surface and an outer surface, separated by means of a viscous fluid, the outer enclosure is fixed to the main body of the spacecraft for rotation therewith once the harpoon is secured to the main body.

Abstract: A device for determining the attitude or variation in attitude of a satellite fitted with an attitude control system comprising at least one inertial actuator. The inertial actuator comprises a rotary element mounted to rotate about an axis of rotation. The rotation of the rotary element is controlled to generate a torque to control controlling the attitude of the satellite. The angular sensor of the device measures the angular rotation of the rotary element about its axis of rotation. The computation unit determines the attitude or variation in attitude of the satellite induced by the rotation of the rotary element as a function of the measurements of angular rotation of the rotary element by the angular sensor. A satellite carrying such a device and a method for determining the attitude or variation in attitude.

Abstract: A method for controlling an attitude control system (30) for a space vehicle (10), the attitude of the space vehicle being controlled during at least one preparation phase followed by an observation phase during which an image capture is performed. In an attitude control system that includes a maneuvering subsystem (300) which includes at least one reaction wheel, the method includes, during the at least one preparation phase, a preparation step (50), during which commands are issued to the maneuvering subsystem in order to control the attitude of the space vehicle, followed by a step (55) of stopping the at least one reaction wheel prior to the observation phase. In addition, during the observation phase, a fine control subsystem (310) having a lower vibration signature than that of the maneuvering subsystem, is sent commands in order to control the space vehicle's attitude. An attitude control system for a space vehicle is also described.

Abstract: A device for controlling the attitude of a satellite exploiting solar pressure, includes at least two solar generators destined to be arranged on either side of a central body of the satellite and each having one face to be exposed to the Sun, referred to as “front face”, the device also including at least three surfaces whose optical properties can be commanded. The surfaces whose optical properties can be commanded are arranged on flaps connected to solar generators, each flap being fixed with respect to the solar generator to which it is connected, and such that, in the operating position, at least two of the surfaces are not parallel when the front faces of the solar generators are optimally oriented with respect to the Sun. The device further includes a module for commanding the optical properties of each surface whose optical properties can be commanded.

Abstract: A device for determining the attitude or variation in attitude of a satellite fitted with an attitude control system comprising at least one inertial actuator. The inertial actuator comprises a rotary element mounted to rotate about an axis of rotation. The rotation of the rotary element is controlled to generate a torque to control controlling the attitude of the satellite. The angular sensor of the device measures the angular rotation of the rotary element about its axis of rotation. The computation unit determines the attitude or variation in attitude of the satellite induced by the rotation of the rotary element as a function of the measurements of angular rotation of the rotary element by the angular sensor. A satellite carrying such a device and a method for determining the attitude or variation in attitude.

Abstract: A device for controlling the attitude of a satellite exploiting solar pressure, includes at least two solar generators destined to be arranged on either side of a central body of the satellite and each having one face to be exposed to the Sun, referred to as “front face”, the device also including at least three surfaces whose optical properties can be commanded. The surfaces whose optical properties can be commanded are arranged on flaps connected to solar generators, each flap being fixed with respect to the solar generator to which it is connected, and such that, in the operating position, at least two of the surfaces are not parallel when the front faces of the solar generators are optimally oriented with respect to the Sun. The device further includes a module for commanding the optical properties of each surface whose optical properties can be commanded.

Abstract: A method for controlling the attitude of a satellite in orbit around a celestial object, the satellite including an observation instrument, a solar panel, a radiator and a star sensor which are arranged on the satellite such that, in a reference frame associated with the satellite and defined by three orthogonal axes X, Y, and Z, the observation instrument has its observation axis parallel to the Z-axis, the solar panel is parallel to the Y-axis, the radiator is arranged on one of the sides ?X, +Y, or ?Y of the satellite, and the star sensor points to the negative X values side. The roll and pitch attitudes of the satellite are controlled during an activity period to direct the observation instrument towards areas of the celestial object to be observed, and the yaw attitude of the satellite is controlled to keep the sun on the positive X values side and ensure that a solar panel minimum insolation constraint is satisfied during observation phases of the activity period.

Abstract: A method for controlling an attitude control system (30) for a space vehicle (10), the attitude of the space vehicle being controlled during at least one preparation phase followed by an observation phase during which an image capture is performed. In an attitude control system that includes a maneuvering subsystem (300) which includes at least one reaction wheel, the method includes, during the at least one preparation phase, a preparation step (50), during which commands are issued to the maneuvering subsystem in order to control the attitude of the space vehicle, followed by a step (55) of stopping the at least one reaction wheel prior to the observation phase. In addition, during the observation phase, a fine control subsystem (310) having a lower vibration signature than that of the maneuvering subsystem, is sent commands in order to control the space vehicle's attitude. An attitude control system for a space vehicle is also described.

Abstract: A method for controlling the attitude of a satellite in orbit around a celestial object, the satellite including an observation instrument, a solar panel, a radiator and a star sensor which are arranged on the satellite such that, in a reference frame associated with the satellite and defined by three orthogonal axes X, Y, and Z, the observation instrument has its observation axis parallel to the Z-axis, the solar panel is parallel to the Y-axis, the radiator is arranged on one of the sides ?X, +Y, or ?Y of the satellite, and the star sensor points to the negative X values side. The roll and pitch attitudes of the satellite are controlled during an activity period to direct the observation instrument towards areas of the celestial object to be observed, and the yaw attitude of the satellite is controlled to keep the sun on the positive X values side and ensure that a solar panel minimum insolation constraint is satisfied during observation phases of the activity period.

Abstract: In order to control the attitude of a satellite having at least four gyroscopic actuators with respective spinners mounted on gimbals steerable about axes parallel to one or the other of only two different directions that are fixed relative to the satellite, the attitude of the satellite is measured using sensors on board the satellite, the control torque required to perform an attitude-changing maneuver is calculated, local linearization calculation is performed based on pseudo-inversion of the Jacobean matrix of the function associating the orientations of the actuator gimbals with the total angular momentum of the cluster in order to determine a new gimbal orientation, and precession speeds of at least one of the gimbals of the actuators are controlled to deliver the control torque for reaching the desired configuration.

Abstract: In order to control the attitude of a satellite having at least four gyroscopic actuators with respective spinners mounted on gimbals steerable about axes parallel to one or the other of only two different directions that are fixed relative to the satellite, the attitude of the satellite is measured using sensors on board the satellite, the control torque required to perform an attitude-changing maneuver is calculated, local linearization calculation is performed based on pseudo-inversion of the Jacobean matrix of the function associating the orientations of the actuator gimbals with the total kinetic moment of the cluster in order to determine a new gimbal orientation, and precession speeds of at least one of the gimbals of the actuators is controlled to deliver the control torque for reaching the desired configuration.

Abstract: For controlling the attitude of a satellite placed on a low earth orbit, components of a vector Bm of the earth's magnetic field along three measurement axes of a frame of reference bound with the satellite (typically by means of a three-axis magnetometer) are measured. The orientation of the earth's magnetic field in the frame of reference is computed and a derivative {dot over (B)}m of the vector is also computed. Magneto-couplers carried by the satellite are energized to create a torque for spinning the satellite at an angular frequency &ohgr;c about a determined spin axis of the satellite, where &ohgr;c is greater than an orbital angular frequency 2&ohgr;0 of the satellite.

Abstract: For controlling the attitude of a satellite placed on a low earth orbit, components of a vector Bm of the earth's magnetic field along three measurement axes of a frame of reference bound with the satellite (typically by means of a three-axis magnetometer)are measured. The orientation of the earth's magnetic field in the frame of reference is computed and a derivative Bm of the vector is also computed. Magneto-couplers carried by the satellite are energized to create a torque for spinning the satellite at an angular frequency &ohgr;c about a determined spin axis of the satellite, where &ohgr;c is greater than an orbital angular frequency 2&ohgr;0 of the satellite.

Abstract: A method is disclosed for controlling the attitude of a satellite by controlling the speed of the gimbals of CMGs in a cluster of CMGs, the CMG having respective wheels mounted on gimbals that are mounted on a satellite platform to rotate about different orientation axes. From starting conditions and end conditions relating to attitude and angular speed and time, a cluster configuration is determined that is remote from any singular configuration such that exchanging angular momentum between the cluster of CMGs and the satellite during a given length of time will give rise to the desired attitude maneuver. The orientation of each gimbal is changed in simultaneous and independent manner into its reference orientation by using an angular position reference, applied in an open loop in the local servo-control of the angular positions of the gimbals.