Abstract: A geostationary orbital box is divided by radially-oriented planes to form orbital sub-boxes. A thruster system facilitates station keeping satellites in each of these orbital sub-boxes. The thruster system includes thruster pairs that are positioned on an anti-nadir face of each satellite and directed through the satellite's center of mass. In addition, multiple satellites can be stationed in each of the sub-boxes by causing them to rotate in a chosen one of a clockwise and a counterclockwise direction and to be spaced from each other in at least one of a radial direction and a normal direction. To enhance the fine-grain control of each of the satellites, the thruster system preferably uses ion-propulsion thrusters.

Abstract: A pyrotechnic ignition device for a gas generator (G), in which: (i) at least in the vicinity of the primary charge (CP), the transmission line (L) is at least substantially perpendicular to the longitudinal axis (X--X) of the outer case (E) of the generator (G); (ii) the end of the transmission line, provided with a deflagrating terminal lead charge (r), emerges in a sealed intermediate chamber (CI); and (iii) the intermediate chamber (CI) is connected to the primary charge (CP) via at least one throttling vent (e) having an axis (1--1) at least approximately parallel to the longitudinal axis (X--X) of the outer case (E).

Abstract: A spacecraft with a spacecraft body having a first axis of symmetry, X, a second axis of symmetry, Y, and a third axis of symmetry, Z. The spacecraft has four thrusters. A control system is provided on the spacecraft which is in electrical contact with the first, second, third and fourth thrusters and which controls the activation and deactivation of the first, second, third and fourth thrusters so that the attitude and orbital velocity of the spacecraft can be controlled only by the first, second, third and fourth thrusters.

Abstract: A method of stationkeeping for a three-axis stabilized satellite having four thrusters mounted in a generally rectangular configuration on an anti-nadir face of the satellite, each of the four thrusters having a line of thrust which passes through the center of mass of the satellite, the four thrusters including a northwest thruster, a northeast thruster, a southwest thruster, and a southeast thruster. The method includes the step of rotating the satellite about a pitch axis that is perpendicular to a normal to the anti-nadir face of the satellite. The northwest thruster and the northeast thruster are canted away from the anti-nadir face in a north direction with respect to a north-south axis which passes through the center of mass of the satellite. The southwest thruster and the southeast thruster are canted away from the anti-nadir face in a south direction with respect to the north-south axis.

Abstract: A method for providing thrust to a space borne vehicle uses an ion beam current to deliver a continuous stream of mass to the vehicle. The mass stream is decelerated thereby transferring its momentum to the vehicle as thrust. The vehicle reaccelerates the mass stream projecting it back to it origin, and thus receives further thrust in reaction to the departing mass stream. The mass stream may be set up between two particle beam accelerators so that thrust is realized by both accelerators, or the beam may be merely received continuously by one accelerator. In both cases the thrust may be used for deep space acceleration to high velocities by a vehicle not carrying fuel or propellant and not near any natural energy source.

Abstract: A method and apparatus for satellite station keeping is disclosed in which six thrusters are mounted on the anti-nadir face of a satellite with their direction of thrust passing through the center of mass (CM) of the satellite. The thrust lines of the north trio of thrusters and the south trio of thrusters make an angle .theta. with the satellite north-south axis in a northern and southern direction, respectively. The four outer thrusters are laterally separated and slewed by an angle .alpha. about the north-south axis. Each outer thruster produces three components of .DELTA.V, i.e. normal, tangential and radial (toward the Earth), thereby providing complete control of the three orbit vectors, inclination, eccentricity and mean motion. The north and south center thrusters are positioned in the Local-Vertical North-South plane and produce only normal and radial .DELTA.V components, providing control for momentum dumping and, in the event of failure, inclination control.

Abstract: A spacecraft (10) carries a solar panel (17) which rotates to follow the sun, and also carries various thrusters (20). Thruster plume impingement on the solar panel affects the torque applied to the spacecraft body (12) in a manner which depends upon solar panel angle. The errors in the thrust during stationkeeping tend to perturb attitude, especially early in the maneuver, because of the delay inherent in the attitude control loop. A torque bias is summed with the residual torque demand signal to correct for the errors in torque. The torque bias signal is generated by a Fourier model of the torques, updated by an adaptive tuning filter, so that successive stationkeeping maneuvers progressively adapt the amplitude and phase of the Fourier coefficients in a manner which tends to minimize the residual torque demand and attitude error. Thus, the torque bias signal automatically approaches the correct value.

Abstract: A method of simultaneously performing a translational maneuver of a spacecraft by a thruster and dumping momentum from the spacecraft during a time period P. The method entails aligning the thruster along a thrust vector which is fixed during the time period P, wherein the thrust vector is aligned with the center of mass of the spacecraft at a time P/2, and firing the thruster throughout the time period P.

Abstract: The orbital launch system is a three stage vehicle to launch orbital payloads. The system uses a turbofan powered aircraft as the first stage with an aerospacecraft attached by an underling aerospacecraft pylon at an aircraft engine mount for carriage. The aerospacecraft is the second stage and is powered by an ejector ramjet engine. The aerospacecraft has a cargo bay with cargo bay doors in its midsection. A booster rocket with payload is launched from the cargo bay by use of an ejection system. Normally the payload is mounted on a rocket booster to be placed in the proper orbit. The orbital launch system may also have a parachute drop recovery system to recover the booster rocket after it deorbits.

Abstract: A system for supporting and selectively positioning an ion thruster (12) relative to a surface (14) of a spacecraft includes three angularly spaced thruster support assemblies (16, 17, 18). Each thruster support assembly includes a frame (20) which has a rotary actuator (42) mounted thereon. The rotary actuator is connected to an actuator member (36) which is rotatably connected to a thruster attachment member (19) connected to a body of the thruster. A stabilizer member (30) is rotatably mounted to the frame and to the thruster attachment member. The thruster is selectively movable in the pitch and yaw directions responsive to movement of the actuator members by the actuators on the thruster support assemblies. A failure of any one actuator on a thruster support assembly will generally still enable limited thruster positioning capability in two directions.

Abstract: A spacecraft includes a three-axis attitude control system. When velocity change thrusters are fired, their plumes impinge on a solar array, at angles which vary with the solar array position. This causes disturbance torques which vary with the solar array position. Disturbance torque information signals or torque bias signals which depend upon the solar array angle are summed with the torque demand signals which control the attitude control system during firing of the velocity change thrusters, to modify the attitude correction torques. The bias torque signals are generated by a Fourier processor based upon stored Fourier coefficients together with signals from a solar array angular position sensor.

Abstract: A wave energy receiving platform installed to track in alignment within a look angle of the sun or a wave energy beaming platform, using holographic windows recorded according to time related positions of the platforms as zone plates to concentrate the wave energy in energy converters, and to columnate light for energy beaming, one embodiment utilizing a circular holographic window for "spot" insolation and a dish-shaped reflector for photovoltaic power assimilation and microwave transmission, a second embodiment utilizing a rectilinear-shaped holographic window for "bar"-shaped beaming and an elongated reflector for photovoltaic power assimilation and microwave transmission, a rectilinear Stirling cycle engine directly operating a rectilinear alternator for generating electrical power, the photovoltaic power synchronized therewith for in-house operation and primary propulsion.

Abstract: A technique for maintaining a satellite in an assigned orbit without control or intervention from the ground. Autonomously obtained navigational data provide a measurement of the actual orbit in which the satellite is traveling. So long as the measured orbit conforms to a desired orbit to within a preselected tolerance, periodic corrections of equal magnitude are made to the satellite's velocity, based on a prediction of the effect of atmospheric drag on the orbit. Measurement of the orbit is made by observation of the time that the satellite passes a reference point in the orbit, such as by crossing the ascending node. If the measured orbit departs from the desired orbit by more than the preselected tolerance, a velocity correction of a magnitude different from the one based on prediction is applied to the satellite. For a decaying orbit, the magnitude of the velocity correction is increased above the correction value based on prediction.

Abstract: A maneuver for minimizing perturbations on a released re-entry body due to ases exhausted from the nozzles of the post-boost control system in which after release of the re-entry body from a position compatible accomplishing with the maneuver, a flip turn is initiated in a near-nozzle-off configuration. The turn is preferably executed in a direction to the side of the direction of the velocity gain required for the platform to reach the next release location. The flip turn is stopped at a lateral escape angle, preferably after turning through an angle of 90 degrees or greater, by initiating an oppositely directed body-axis turn. After being accelerated for a lateral escape time, the platform is oriented in the direction of the required gain in velocity to reach the next release location and coarse thrust is activated. Prior to arrival at the release location, a body-axis turn is accomplished to orient the platform in the proper position for the next release event.

Abstract: A three-axis stabilized spacecraft includes a plurality of primary attitude control thrusters, the torque vectors of which lie in, or parallel to a primary plane. It also includes at least two more secondary attitude control thrusters, the torque vectors of which lie in a secondary plane which is not parallel to the primary plane. The control system produces attitude error signals, which are processed with a PID characteristic to produce impulse demand signals, all in known fashion. The impulse demand signals are transformed into an auxiliary coordinate system, in which two of the three auxiliary axes lie in the primary plane, and the third is orthogonal thereto. One of the secondary thrusters is selected, which has, along the third auxiliary axis, the largest torque magnitude and the same sign as the transformed impulse demand.

Abstract: A satellite perigee velocity augmentation method wherein a satellite is steered throughout the perigee velocity augmentation maneuver such that its thrust vector is always oriented approximately opposite to the direction of motion of the satellite. The satellite is pitched around a predetermined axis (e.g. the Y-axis) such that the thrust vector is always pointing approximately opposite to the direction of motion of the satellite. The satellite is steered during the perigee velocity augmentation maneuver in order to achieve the desired attitude wherein the thrust vector is always oriented approximately opposite to the direction of motion of the satellite is accomplished by pitching the satellite around the predetermined axis such that the thrust vector is always pointing approximately opposite to the direction of motion of the satellite. By steering the satellite in accordance with the present perigee velocity augmentation method, overall efficiency achieved is increased.

Abstract: A technique for maintaining a satellite in an assigned orbit without control or intervention from the ground. Autonomously obtained navigational data provide a measurement of the actual orbit in which the satellite is traveling. So long as the measured orbit conforms to a desired orbit to within a preselected tolerance, periodic corrections of equal magnitude are made to the satellite's velocity, based on a prediction of the effect of atmospheric drag on the orbit. Measurement of the orbit is made by observation of the time that the satellite passes a reference point in the orbit, such as by crossing the ascending node. If the measured orbit departs from the desired orbit by more than the preselected tolerance, a velocity correction of a magnitude different from the one based on prediction is applied to the satellite. For a decaying orbit, the magnitude of the velocity correction is increased above the correction value based on prediction.

Abstract: Position control methods are described for satellites and spacecraft for controlling transition from thruster control to momentum wheel control in a three-axis stabilized spacecraft. Transition from a high-bandwidth, high-torque thruster-controlled stationkeeping (SK) mode to a low bandwidth, low torque momentum wheel On-Orbit Mode is carried out. Usually a unique threshold entry method to automatically initiate the transition mode at the point with the most favorable dynamics. Also, the disclosed method eliminates the use of nutation in conjunction with a deadbeat thruster sequence to correct the spacecraft attitude to improve pointing performance and significantly shorten the time spent in the transition mode.

Abstract: A method of controlling the attitude of a satellite according to which the direction of a predetermined celestial object is defined in a frame of reference related to the satellite, the instantaneous angular velocity vector of the satellite is detected and, by means of an actuating assembly, torques are applied to the satellite which are defined by a control law so as to rotate the satellite about the direction while orienting an aiming axis related to the satellite in the same direction, involves defining the direction of the predetermined celestial object in a frame of reference related to the satellite by a first quantity representing a first angle measured between an axis of sight and the projection of the direction onto a first reference plane containing the axis of sight and by a second quantity representing a second angle defined by the axis of sight and the projection of the direction onto a second reference plane containing the axis of sight, the second angle being calculated from the first angle and

Abstract: A thrust maneuver system for steerable vehicles comprising a plurality of thrusters of varying impulsive force, some of which provide a base force, and others varying multiples of the base force. The forces may be used additively or subtractively to obtain a desired force for any given maneuver.

Abstract: A method and apparatus for satellite station keeping is disclosed in which four thrusters are mounted on the anti-nadir face of the satellite with their direction of thrust passing through the center of mass of the satellite. The thrust lines of the north pair (20, 22) of thrusters and the south (24, 26) pair of thrusters make an angle .theta. with the satellite north-south axis in a northern and southern direction respectively. The thrusters are laterally separated and slewed by an angle .alpha. about the north-south axis. Each thruster produces three components of .DELTA.V, i.e. normal, tangential and radial (toward the Earth), thereby providing complete control of the three orbit vectors, inclination, eccentricity and mean motion. In the event of failure of a thruster, the thruster diagonally opposite the failed thruster is shutdown and the remaining diagonal pair of thrusters is used to maintain station keeping.

Abstract: A satellite thruster system capable of creating a high velocity plasma jet is disclosed. The plasma accelerator, or "railthruster," features a high energy current pulse source and a geometrically configured coaxial or parallel dual-rail ignitor system for higher velocity, and thus more fuel efficient, satellite attitude control. A ratio of a length of the railthruster to a spacing between the rails is at least 3:1.

Abstract: This device is used for controlling the attitude of a spacecraft to be rotated about a body's axis of rotation. Actuators generate torques about the axis of rotation and two lateral axes. Angular velocity signals .omega..sub.X, .omega..sub.Y with respect to the lateral axes are in each case fed to first and second signal paths. The latter contain an integrator. Modulators, which each comprise a variable dead zone, supply control signals for the actuators. In order to limit the nutation amplitude to a constant value in a reliable manner, multiplication elements are provided in the first and second signal paths. The lateral-axis angular velocity signals .omega..sub.X, .omega..sub.Y or the angular position signals .PHI., .theta. are acted upon by factors which are proportional to the rotation axis angular velocity signal .omega..sub.Z or its square in the multiplication elements. Furthermore, the thresholds of the dead zones of the modulators are varied proportionally to .omega..sub.Z.sup.2.

Abstract: In the preferred embodiment of the invention, a cooled bipropellant thruster 70 for controlling the on-orbit position and orientation of a spacecraft is provided. The cooled bipropellant thruster 70 uses a liquid fuel and liquid oxidizer. The liquid fuel is decomposed in a first chamber 72 with a catalytic bed of decomposition material 74 and produces at least one reaction gas, which flows to the second reaction chamber 90. The second reaction chamber 90 is heated by the reaction gas, but is cooled by liquid oxidizer flowing through cooling passages 92, 94, 98, and 102, which brings the oxidizer into a heat exchange relationship with the second reaction chamber 90. During the heat exchange relationship, heat is transferred from the second reaction chamber 90 to the oxidizer and the oxidizer transforms into a gas. The gaseous oxidizer is fed into a second reaction chamber 90 to secondarily react with the reaction gas.

Abstract: The estimation and compensation of fixed, but unknown uncertainties of a thruster (22) for improving satellite attitude estimation and control as well as eliminating the need for nutation damping devices is disclosed. A thruster (22) is fired and an attitude state is estimated using an estimator (116). A commanded rate change (122) is calculated, which is modified using a compensating feedforward command (126) as updated by a fixed uncertainty estimator (124) unless an estimated rate is less than an absolute value of a threshold rate. The modified commanded rate change (130) is used to incrementally adjust thruster fire on-time (104) until a predetermined satellite trajectory is reached.

Abstract: A 3-axis stabilized spacecraft has primary and secondary attitude control thruster strings, thrusters in each string exerting roll, pitch and yaw torques. The primary and secondary thruster strings are similar and exhibit paired thrusters oriented on opposite sides of an East/West axis passing through the spacecraft. A stationkeeping input energizes the North or South thrusters to cause a maneuver of the spacecraft along a North/South axis, the thrusters effecting a perturbation in the spacecraft's attitude. An attitude control system energizes at least a primary string thruster to counteract the attitude perturbation, the thruster being oriented so as also to cause a change in the spacecraft's East/West orbit velocity.

Abstract: A spacecraft uses monopropellant arcjets for velocity change such as for north-south stationkeeping. It has been discovered that, while an arcjet cannot be modulated by pulsing the fuel supply, the amount of thrust can be varied by modulating the power applied to the arc, without extinguishing the arc. While the specific impulse (I.sub.SP) of the arcjet is thereby reduced from the maximum I.sub.SP of which the arcjet is capable, the resulting I.sub.SP may still be larger than the combined I.sub.SP of an unmodulated arcjet in conjunction with a modulated chemical thruster in a typical scenario. According to the invention, attitude control is provided in conjunction with north-south stationkeeping or other velocity change by, in response to an error signal generated by an attitude control system, modulating the arc power(s) of an arcjet thruster(s), which provides the velocity change. The arc is not extinguished during the stationkeeping maneuver, but is varied in magnitude.

Abstract: A triaxially stabilized satellite having a Cartesian axis system with mutually perpendicular X, Y and Z axes, two electric propulsors for orbital maneuvers and attitude control of the satellite and having respective versors including a right angle between them and lying in an X-Y plane, the versors being orientable in the plane about the Z axis to include a variable angle a with the X axis to impart two degrees of freedom of movement to the electric propulsors, the electric propulsors generating thrust vectors in line with the versors away from a center of gravity of the satellite at an intersection of the versors, the electric propulsors being firable independently and for respective angles of arc in their displacement with the degrees of freedom to maneuver the satellite orbitally, control attitude of the satellite and dissipate angular momentum of the satellite. The electric, preferably ionic, pulsars can be used with triaxially stabilized satellites with an LEO or GEO.

Abstract: A unified spacecraft attitude control system includes a memory aboard the spacecraft, in which a linear transformation matrix [.alpha.] is stored, which includes information identifying pseudo-complementary pairs of thrusters, and the characteristics of each pseudo-complementary pair. During each control cycle of the spacecraft attitude control system, the error signal is multiplied by a gain representing a desired slew rate to form pulse-width signals {pw} for the pseudo-complementary paired thrusters. An augmented pulse-width vector matrix {PW} is formed by transformations, to eliminate negative values of pulse width. The actual thruster pulse widths {.DELTA.t} are calculated as {.DELTA.t}=[.alpha.]{PW}. The thrusters are energized by limited values of {.DELTA.t}.

Abstract: A rocket deceleration system for a spacecraft, comprises a first set of active canted rockets for attenuating a horizontal velocity of the spacecraft and a portion of the vertical velocity thereof. A second set of active canted rockets attenuate the remainder of the vertical velocity. A third set of available canted rockets attenuate a wide range of horizontal velocities, regardless of the vehicle roll position about its vertical axis. The first set, second set and third set of rockets form a ring and combine to form a total number of rockets being divisible by the numeral 6. Each rocket is 180.degree. from an opposing rocket on the other side of the ring. A programmable controller identifies rockets to be fired to attenuate horizontal and vertical spacecraft velocities.

Abstract: The three axes thruster modulation (8) of the present invention accepts three axes of input torque commands or angular acceleration commands and generates thruster selection and thruster timing (40) information which is used to fire thrusters (48) for the purpose of spacecraft attitude control and velocity change maneuvers. The modulation logic (8) works in all three axes simultaneously and is suitable for use with an arbitrary thruster configuration, including a configuration in which individual thrusters or thruster groups do not produce torques about mutually orthogonal axes. After thruster selection and on-times have been determined, the modulation logic (8) uses this information to compute a best estimate of the actual rate change (42) which is then compared to the commanded rate change (44) to develop a residual unfired rate change.

Abstract: A space transfer vehicle has a plurality of thrusters for maneuvering in six degrees of freedom about three orthogonal vehicle axes. The space transfer vehicle includes four box-like thruster modules which each house an identically arranged plurality of thrusters. The thrusters are selectively energized in pairs to produce torque about the three orthogonal axes with a first magnitude for maneuvering the space transfer vehicle without a payload, and of a second magnitude for maneuvering the space transfer vehicle with a payload.

Abstract: Roll and yaw attitude control method for a satellite stabilized about its roll, yaw and pitch axes embodying a momentum wheel system generating a continuous angular momentum substantially parallel to the pitch axis and having a variable component at least approximately parallel to the roll-yaw plane and a continuously acting actuator system in which the roll and/or yaw attitude of the satellite is sensed. Control signals are applied to the momentum wheel system that are produced by a fast control loop using a known fast control law and second control signals are applied to the continuously acting actuator system that are produced by a slow control loop using a known slow control law. The continuously acting actuator system is loaded in fixed direction of the satellite parallel to the variable component if the latter has a fixed direction.

Abstract: A spacecraft includes bipropellant and monopropellant engines or thrusters. The oxidizer-fuel mixture ratio of the bipropellant engine is not known exactly. The spacecraft is loaded with only sufficient oxidizer to achieve the velocity for transfer from an intermediate orbit to geosynchronous orbit if the mixture ratio is nominal. Therefore, more fuel can be loaded. If the bipropellant engine burn is nominal, there is no excess oxidizer when on-orbit and more fuel is available for stationkeeping. If the burn is oxidizer-rich, there is a velocity shortfall, which is made up by firing monopropellant engines. If the burn is oxidizer-lean, the geosynchronous orbit is achieved with a load of excess oxidizer, which must be moved during each stationkeeping maneuver. A net gain of stationkeeping time results in any of the three mixture ratio cases by comparison with loading of sufficient oxidizer for a full bipropellant burn under worst-case mixture conditions.

Abstract: A method is disclosed wherein a flexible space craft may be slewed by the application of positive and negative acceleration forces applied about a slewing axis. The method is such that at the end of the application of the slewing forces there is no residual energy in the excited modes. By examination of the response of an undamped and then damped structural mode to a sequence of step forces--entirely within the premises of structural dynamics discipline--a minimum-time zero-residual-energy torque profile with unequal intervening pulses is arrived at heuristically. Rigorous yet simple relationships are then established among the maneuver angle of a rest-to-rest slew, slew time, widths of the intervening pulses, and natural frequency and damping of a critical mode whose energy at the end of slew must be zero.

Abstract: A method for controlling reorientation of a spacecraft's spin from a minor axis spin bias to a desired major axis spin after spin transition. A control system monitors rotational rates about the principal axes to detect a separatrix crossing of a polhode path therein. Controlled thruster firings resulting from spin rate information successively decrease and increase a characteristic parameter and capture the spacecraft during a spin transition to a desired major bias orientation. It is possible to monitor only .omega..sub.1 and .omega..sub.3 in an alternate embodiment.

Abstract: Thrusters in a propulsion system of a spacecraft spin stabilized by rotation about a spin axis are fired to increase the orbital velocity of the spacecraft in a maneuver direction along the orbital velocity vector. The propulsion system comprises a pair of thrusters juxtaposed on a common support at the periphery of the spacecraft. The thrusters have thrust axes perpendicular to the spin axis and offset relative to a transverse axis of the spacecraft by equal and opposite offset angles. Each thruster is fired separately and alternately when its thrust axis is substantially parallel to the maneuver direction while the spacecraft is rotating about its spin axis.

Abstract: A method for controlling reorientation of a spacecraft's spin from a minor axis spin bias to a desired major axis spin after spin transition. A control system monitors rotational rates about the principal axes to detect a separatrix crossing of a polhode path therein. Controlled thruster firings resulting from spin rate information successively decrease and increase a characteristic parameter and capture the spacecraft during a spin transition to a desired major axis bias orientation. It is possible to monitor only .omega..sub.1 and .omega..sub.3 in an alternate embodiment.

Abstract: A satellite adapted to be spin-stabilized in geostationary orbit having, coaxial with a spin rotation axis, a satellite surrounded with a solar generator. At least two equipments including an apogee maneuver system are disposed along the rotation axis. A set of generally annular antennas including at least one picture transmission antenna is disposed on one of the NORTH and SOUTH faces of the satellite so as to leave at its center a cylindrical space along the spin rotation axis to house one of the equipments. The other of the equipments is disposed on the other of the NORTH and SOUTH faces.

Abstract: The attitude of a satellite carrying terrestrial and solar sensors and spin-stabilized about an axis V--V is determined and controlled prior to its transfer from an elliptical transfer orbit to a circular geostationary orbit by means of an apogee motor firing. The attitude is defined relative to an inertial X-Y-Z frame of reference the Z axis of which is directed towards geographical North, by a declination .alpha. between the axis V--V and the X-Y plane and by a right ascension .beta. between the projection of the axis V--V onto the X-Y plane and the X axis. After injection of the satellite by a launch vehicle into the transfer orbit at its perigee, with an initial attitude approximating the predetermined final attitude for the apogee motor firing, the right ascension .beta. of the satellite is modified to confer on it an intermediate attitude such that the earth is in the field of view of the terrestrial sensors for a position of the satellite in the transfer orbit offset at least 10.degree.

Abstract: An improvement to a variable-pressure solid-propellant-powered maneuvering ystem for spacecraft, enabling the system to operate for longer than one propellant burn time. At least two solid propellant gas generators are connected via a manifold to a plurality of nozzle valve clusters; at least one of the gas generators is connected to the manifold via a sequence valve which isolates that generator from the manifold until such time as it is desired to put that generator into operation.

Abstract: A device is disclosed for regulating a set value and/or for stabilizing elastic objects subject to spin and free to move around their axis of rotation, in particular aircraft and spacecraft. For that purpose, the regulating signals required to regulate the set value or to stabilize the freely moving objects can be obtained by means of a regulator having a transfer function with a denominator degree about three orders higher than the numerator.

Abstract: An improved method for satellite station keeping is disclosed. The method provides for station keeping of a three axis stabilized satellite 10 using only two thrusters 20 and 22. The thrusters 20 and 22 can be ion or liquid propulsion thrusters and are mounted on the anti-nadir face 18 of the satellite 10. The north thruster 20 is canted at an angle .THETA. from the north-south axis 16 of the satellite 10 in a northern direction and the south thruster 22 is canted at the angle .THETA. from the north-south axis 16 in a southern direction. Both thrusters 20 and 22 are also translated to the east or west along an east-west axis 14 of the satellite 10 and swiveled at variable angles .alpha..sub.1 and .alpha..sub.2 respectively. A specific teaching of the invention discloses techniques for determining the angles .alpha..sub.1 and .alpha..sub.2 and the firing positions for the thrusters 20 and 22 to maintain the satellite 10 in a stationary orbit.

Abstract: A stabilization system for a spacecraft (10) which enables the spacecraft to be stabilized by rotation about any principal moment of inertia axis. The system includes two pairs of control thrusters (14, 16, 18, 20) for producing positive and negative control moments about two orthogonal axes mutually perpendicular to the axis of rotation of the spacecraft. The control system (40) includes rate gyros (42, 46) which provide error signals which are sent to duty cycle modulators (54). The duty cycle modulators provide a pulse width modulated control signal to the control thrusters to approximate proportional control of spacecraft attitude.

Abstract: A system for controlling the orbit of a satellite by operating a plurality of thrusters is disclosed. In the system, an actual attitude of the satellite is sensed, an evaluation is set up on the basis of the sensed attitude and compared with a threshold which is adequately changing, and the ON-OFF condition of the firing of the thrusters is based on the relationship between the evaluation value and the threshold.

Abstract: An improved thrust vector control system for steering and controlling an aerospace vehicle propelled by a reaction type motor. The improved thrust vector control system simultaneously rotates and laterally translates the reaction motor with respect to the longitudinal axis of the vehicle. This complex motion of the reaction motor generates sufficiently large control moments that allows the reaction motor to be moved very close to the center of gravity of the vehicle. As a result, the vehicle can be shortened and the structure that is typically required to position the reaction motor at a swivel point farther aft eliminated.

Abstract: A spacecraft, and related method for its operation, for transporting a payload, such as a satellite, from a space shuttle in a low-altitude parking orbit, to an operational orbit. Housekeeping functions, such as communications, attitude control, and power-supply, are performed by subsystems integrated into the spacecraft and employed both while in the operational orbit and during ascent from the parking orbit. The payload is secured forward of a payload platform having forward and aft faces of isogrid construction, and the housekeeping subsystems are stored between the faces, an interface of electrical and other connections being provided to the payload through the forward platform face. A liquid bipropellant rocket engine secured behind the payload platform provides low thrust and relatively low acceleration, and is operated in a succession of short perigee burns to extend the orbit to a desired altitude, and then in one or more apogee burns to circularize the orbit, if the payload is a satellite.

Abstract: The two-liquid propulsive system for an artificial satellite is characterized in that the components of the propellant are unequally distributed in at least two pairs of tanks (12, 16) and (14, 18) which are associated in such a way as to provide additional fuel in a first pair of tanks and additional oxidizer in a second pair of tanks, and in that the different pairs of tanks are suitable for being used in succession during predetermined time periods so that the exhaustion of a first propellant component in one tank (14 or 16) indicate that the residual normal lifetime of the satellite is at best approximately equal to said predetermined time period, and that after exhaustion of the second propellant component in the tank (16 or 14), the two tanks (12 and 18) each containing an excess quantity of one of the propellant components are associated in order to extract the satellite.

Abstract: Device and method for aiming a space probe toward a celestial body. It comprises a solar sail (30, 31) having an asymmetry about an axis (Z) and which subjects the probe (S) to a tilting torque of solar pressure. A kinetic wheel (20) turns about a perpendicular axis (X). This results in a rotation of the probe about the axis perpendicular to the two preceding axes (Y). The rotational speed of the wheel (20) is varied by a control system (23, 24) in order to change the rotational speed of the probe.Application of the invention is to space probes that lie in the plane of the ecliptic.

Abstract: An improvement to an integrated valve assembly which generally consists of a cluster of two poppet valves, four electric-solenoid-operated flapper valves, and four thrust nozzles and interconnecting plumbing. The improvement to the integrated valve assembly reduces the force required to operate the flapper valves thereby minimizing solenoid size, weight, and power consumption. The improvement consists of a modified flapper valve tip having a hole bored through the tip in the direction of tip motion, and a free-fitting piston located therein and suitably axially restrained relative to the flapper valve body.