Abstract: A device for producing energy includes an air-towed vessel, and at least one water current turbine linked to the vessel by at least one electric cable. The water current turbine is linked to the vessel by at least one mechanical linking cable to be towed by the vessel. The water current turbine is spaced apart from the vessel, which makes it possible to increase the diameter of the turbine and to reduce the interactions between the turbine and the vessel. Moreover, it is then possible to provide a plurality of water current turbines towed by the same vessel.

Abstract: A combined system for imaging and communication by laser signals including a telescope (10) in which the primary (1) and secondary (2) mirrors are shared between an imaging function and a function involving the emission of laser transmission signals. The accuracy required for the direction of emission (DE) of the laser transmission signals is obtained by additionally placing a geolocation device on board a satellite carrying the combined system. No coarse pointing assembly is used and it is also possible for the system to be devoid of any fine pointing assembly and target acquisition and tracking detector.

Abstract: A combined system for imaging and communication by laser signals including a telescope (10) in which the primary (1) and secondary (2) mirrors are shared between an imaging function and a function involving the emission of laser transmission signals. The accuracy required for the direction of emission (DE) of the laser transmission signals is obtained by additionally placing a geolocation device on board a satellite carrying the combined system. No coarse pointing assembly is used and it is also possible for the system to be devoid of any fine pointing assembly and target acquisition and tracking detector.

Abstract: A method to control a sunlight acquisition phase of a spacecraft with a nonzero angular momentum of an axis DH. The spacecraft includes a solar generator configured to rotate about an axis Y. The spacecraft actuators are controlled to place the spacecraft in an intermediate orientation in which the axis Y is substantially orthogonal to the axis DH. The solar generator is controlled to orientate the solar generator towards the sun. The spacecraft actuators are controlled to reduce the angular momentum of the spacecraft. The actuators of the spacecraft engine are controlled to place the spacecraft in an acquisition orientation in which the axis Y is substantially orthogonal to the direction of the sun with respect to the spacecraft.

Abstract: A method to control a sunlight acquisition phase of a spacecraft with a nonzero angular momentum of an axis DH. The spacecraft includes a solar generator configured to rotate about an axis Y. The spacecraft actuators are controlled to place the spacecraft in an intermediate orientation in which the axis Y is substantially orthogonal to the axis DH. The solar generator is controlled to orientate the solar generator towards the sun. The spacecraft actuators are controlled to reduce the angular momentum of the spacecraft. The actuators of the spacecraft engine are controlled to place the spacecraft in an acquisition orientation in which the axis Y is substantially orthogonal to the direction of the sun with respect to the spacecraft.

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: An electric motor (1) with permanent magnets includes a rotor (4), on which permanent magnets are fastened (6), and a stator (2). The stator includes a stator structure and coils (5) installed on the stator structure. The stator structure is realized by an assembly of at least three independent stator elements (21), assembled on a baseplate (3) with no direct mechanical linkage between them. Each stator element (21) is fastened onto the baseplate (3) of the motor by an adjusted fastener (31) and at least one anti-rotation element (32). Preferably, the stator elements (21) are made of a material that is a good heat conductor and electrical insulator, such as a ceramic.

Abstract: An attitude control actuator of a spacecraft includes a first momentum wheel driven in rotation by a motor and a second momentum wheel. Both momentum wheels are movable in rotation about an axis and are mechanically coupled by coupling means imposing between a rotation speed ?1 of the first momentum wheel and a rotation speed ?2 of the second momentum wheel a ratio R=?2/?1, negative on the one hand and continuously modifiable by the coupling means in response to a command on the other hand so as to modify the total angular momentum of the actuator while the total kinetic energy of the wheels are kept constant. In one embodiment, both momentum wheels have the same inertia and are coupled through a toroidal variable rotation speed drive, where ratio R varies between ?3 and ??. The motor drives the momentum wheels and operates as a generator for braking the momentum wheels.

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: An electric motor (1) with permanent magnets includes a rotor (4), on which permanent magnets are fastened (6), and a stator (2). The stator includes a stator structure and coils (5) installed on the stator structure. The stator structure is realized by an assembly of at least three independent stator elements (21), assembled on a baseplate (3) with no direct mechanical linkage between them. Each stator element (21) is fastened onto the baseplate (3) of the motor by an adjusted fastener (31) and at least one anti-rotation element (32). Preferably, the stator elements (21) are made of a material that is a good heat conductor and electrical insulator, such as a ceramic.

Abstract: An actuator device for varying the attitude of a spacecraft includes a reversible conversion chain of electrical energy to mechanical rotation energy of a flywheel. The electrical energy is stored in a capacitive element that may be a supercapacitor. The actuator device also includes an electrical power converter, connected, on one hand, to the capacitive element and intended to be connected, on the other hand, to the spacecraft power bus. The converter makes it possible to compensate for losses to keep a total energy of the actuator device constant.

Abstract: An actuator device for varying the attitude of a spacecraft includes a reversible conversion chain of electrical energy to mechanical rotation energy of a flywheel. The electrical energy is stored in a capacitive element that may be a supercapacitor. The actuator device also includes an electrical power converter, connected, on one hand, to the capacitive element and intended to be connected, on the other hand, to the spacecraft power bus. The converter makes it possible to compensate for losses to keep a total energy of the actuator device constant.

Abstract: An attitude control actuator of a spacecraft includes a first momentum wheel driven in rotation by a motor and a second momentum wheel. Both momentum wheels are movable in rotation about an axis and are mechanically coupled by coupling means imposing between a rotation speed ?1 of the first momentum wheel and a rotation speed ?2 of the second momentum wheel a ratio R=?2/?1, negative on the one hand and continuously modifiable by the coupling means in response to a command on the other hand so as to modify the total angular momentum of the actuator while the total kinetic energy of the wheels are kept constant. In one embodiment, both momentum wheels have the same inertia and are coupled through a toroidal variator, where ratio R varies between ?3 and ?1/3. The motor drives the momentum wheels and operates as a generator for braking the momentum wheels.