Abstract: The invention relates to a security-protected system for positioning by satellites, comprising a constellation of satellites (11) sending out positioning signals under the control of a set of ground stations (14). A user receiver of the said positioning signals comprises means for sending, to a ground station, a request calling for a key which is necessary for interpreting them, advantageously accompanied by a recopy of the positioning signals received. User servicing ground stations comprise means for receiving this request, calculating the position of the user and verifying whether the user possesses a privileged status, and means for addressing the said key to the user receiver, in the event that the verification is positive, this key further comprising means for interpreting the positioning signals with the aid of the key so as to deduce his own position therefrom.

Abstract: The invention relates to a rocket engine nozzle comprising a system for controlling jet separation of the flow in the nozzle, wherein said control system exhibits a plurality of separation triggering elements (5, 10) arranged in such a way as to generate, from mutually spaced initiation points (9), distinct zones (6) of jet separation, so as to form a three-dimensional separation of the flow. The flow control system can exhibit at least two triggering elements (5, 10).

Abstract: The invention relates to a propulsion device comprising a gas ejection nozzle and an injection chamber for injecting at least one propellant fluid. According to the invention, the device has an induction loop which surrounds a zone of the nozzle and also an electricity generator to feed said induction loop, in particular under drive from a heat engine whose heat source is a nuclear core and whose heat sink is a cryogenic liquid which is subsequently used for propulsion.

Abstract: The invention relates to a propulsion device comprising a gas ejection nozzle and an injection chamber for injecting at least one propellant fluid. According to the invention, the device has an induction loop which surrounds a zone of the nozzle and also an electricity generator to feed said induction loop, in particular under drive from a heat engine whose heat source is a nuclear core and whose heat sink is a cryogenic liquid which is subsequently used for propulsion.

Abstract: The invention relates to a propulsion device comprising a gas ejection nozzle and an injection chamber for injecting at least one propellant fluid. According to the invention, the device has an induction loop which surrounds a zone of the nozzle and also an electricity generator to feed said induction loop, in particular under drive from a heat engine whose heat source is a nuclear core and whose heat sink is a cryogenic liquid which is subsequently used for propulsion.

Abstract: The invention relates to a rocket engine nozzle comprising a system for controlling jet separation of the flow in the nozzle, wherein said control system exhibits a plurality of separation triggering elements (5, 10) arranged in such a way as to generate, from mutually spaced initiation points (9), distinct zones (6) of jet separation, so as to form a three-dimensional separation of the flow.

Abstract: The invention relates to a security-protected system for positioning by satellites, comprising a constellation of satellites (11) sending out positioning signals under the control of a set of ground stations (14). A user receiver of the said positioning signals comprises means for sending, to a ground station, a request calling for a key which is necessary for interpreting them, advantageously accompanied by a recopy of the positioning signals received. User servicing ground stations comprise means for receiving this request, calculating the position of the user and verifying whether the user possesses a privileged status, and means for addressing the said key to the user receiver, in the event that the verification is positive, this key further comprising means for interpreting the positioning signals with the aid of the key so as to deduce his own position therefrom.

Abstract: A structural cryogenic tank wall has an outer skin and an inner skin between which is a cavity containing a thermally insulative structure. The cavity is empty of any gas and contains at least one sensor for continuously verifying that the vacuum is maintained in order to monitor the structural integrity of the outer and inner skins and sealing of the cryogenic tank.