Abstract: High precision spacecraft attitude determination is produced by specially positioning the spacecraft's star trackers and then filtering out measurement errors produced from star tracker electronics. In addition to the conventional azimuth and elevation controls used for star tracker pointing, the star tracker detector array is rotationally positioned about its boresight so that its pixels are traversed by the imaged star path at an angle within 20° of diagonal. This forces both vertical and horizontal spatial error components in the detector plane to a high frequency range at which they can easily be filtered out in common.

Abstract: Navigation satellite receiver measurements of the acceleration of a moving vehicle are used to derive valuable attitude information about the vehicle. Three-dimensional accelerometer measurements aboard the vehicle are used to determine the specific force vector in the bow frame. The navigation satellite receiver measurements allow determination of the specific force vector in the earth-fixed frame. The specific force vector measured in both vehicle and earth-fixed frames can be used with additional information to derive vehicle attitude.

Abstract: A method for the on the whole minimum-fuel, computer-assisted control of an optionally determined number of thrusters, arranged as desired on a spacecraft, is to be specified, which method solves this linear optimization problem within the shortest possible time by reducing the computation expenditure. The method depends on the dual simplex algorithm and a suitably provided dual permissible start table. The dual permissible start table is set up on the basis of a previously computed optimum table and the transformation of the actual forces-moments vector belonging to the selected start table. Specific processing steps in the dual simplex algorithm are either not needed at all or are substituted with processing steps that require considerably less computation expenditure. Finally, a reduced table is used in place of the simplex table.

Abstract: An attitude control system and method operative with a thruster controls the attitude of a vehicle carrying the thruster, wherein the thruster has a valve enabling the formation of pulses of expelled gas from a source of compressed gas. Data of the attitude of the vehicle is gathered, wherein the vehicle is located within a force field tending to orient the vehicle in a first attitude different from a desired attitude. The attitude data is evaluated to determine a pattern of values of attitude of the vehicle in response to the gas pulses of the thruster and in response to the force field. The system and the method maintain the attitude within a predetermined band of values of attitude which includes the desired attitude. Computation circuitry establishes an optimal duration of each of the gas pulses based on the pattern of values of attitude, the optimal duration providing for a minimal number of opening and closure operations of the valve.

Abstract: The present invention provides a vibration isolation system. The Airborne Stabilization/Vibration Isolation System (AS/VIS) is a combination of advanced pneumatic passive suspension, high-capacity voice-coil actuators, integrated sensors, a control processor and a commercial system of software development tools. The entire vertical weight load is borne by the pneumatic mounts. Vertical payload motion is accommodated with little or no friction through the use of air bearings at all sliding surfaces of the mounts. The high-force voice-coil actuators provide a variety of performance enhancements to the passive isolation system. Primarily, they allow control of the payload mean position in the presence of low-frequency quasistatic load variations due to aircraft maneuvering. Horizontal and vertical displacement sensors detect the position of each actuator moving element relative to ground. The controller sends a signal to power amplifiers, which drive the horizontal and vertical voice-coil actuators.

Abstract: A method is disclosed for targeting a satellite orbiting earth between to sites on earth based on an access time that is transmitted from a ground station. Control momentum gyros are used to change the satellite's attitude for targeting. A gryo rate is selected based the longest time to target. The longest time is a value selected from the access time, the time to reach the target based on the satellite's attitude and the time to reach the target based on the gyro rate.

Abstract: In an electric propulsion system used for transferring a satellite to its operational orbit, a solar array adjustment system is controlled to compensate on a continuous basis for the attitude gyrations required by electric thrust vector optimization. The solar array control operates to maintain the solar array in a perpendicular orientation to the sun vector for optimum power generation.

Abstract: A tether (FIG. 6) having the special technical feature of multiple primary load-bearing lines (601,603) and normally slack secondary lines (605, 603). These primary and secondary lines are connected together with knotless, slipless interconnections so the tether maintains high strength and some of the lines can be cut without failure of the tether when it is operated near the ultimate failure load of the material from which it is constructed. This tether can safely carry (FIG. 31) load hundreds of times longer than prior art tethers in harsh environments where a single-line tether experiences a substantial risk of failure. The specific industrial applications of an electrodynamic tether system to deorbit satellites and a low Earth orbit to lunar surface tether transport system are all part of the general innovative concept of the invention.

Abstract: A payload control system and payload controller for a payload onboard an outer space vehicle having a host computer system are provided. The payload controller includes a unitary compact control unit mounted on a circuit board. The control unit includes a processor, memory, display device control logic, input device control logic, and data input/output control logic. A plurality of interfaces located about the board surfaces provide communication with payload and host system components. A computer readable storage medium mounted on the circuit board stores information to control the payload when the payload is in outer space. The information stored in the computer readable storage medium is non-permanent so that the payload controller may be re-used for different payload experiments. The unitary compact control unit includes sufficient components to function as a stand alone computer capable of running an operating system while supporting a display device and an input device.

Abstract: A global communications network comprises a plurality of aerial platforms or vehicles deployed at an altitude in or near the stratosphere and permitted to drift in a controlled manner such that each platform adjusts its position relative to other aerial platforms. Each aerial platform has a propulsion system and control surfaces and preferably includes a lighter-than-air component to maintain lift in an economical manner. Each aerial platform also includes a payload, means for communicating with other aerial platforms and a control system including location-finding equipment and a processor adapted for directing the platform's propulsion system and control surfaces to effectuate changes in the aerial platform's position relative to other aerial platforms based on position information, and optionally on other factors such as terrestrial demand for services provided by the payload of the aerial platforms.

Abstract: A navigation system for spinning projectiles using a magnetic spin sensor to measure the projectile roll angle by sensing changes in magnetic flux as the projectile rotates through the earth's magnetic field is disclosed. The magnetic spin sensor measurements are used to despin a body reference frame such that position, velocity, and attitude of the projectile can be determined by using a strapdown inertial navigation system (INS) algorithm. More particularly, a multisensor concept is used to measure pitch and yaw angular rates, by measuring Coriolis acceleration along the roll axis and demodulating the pitch and yaw rates therefrom.

Abstract: A method for use in a spacecraft for controlling yaw angle deviations from a desired yaw angle profile. The method includes the steps of: (a) operating a profile generator to output roll angle, pitch angle, yaw momentum, and yaw angle profiles, the profiles being calculated to meet spacecraft pointing requirements while operating in an inclined orbit; (b) inputting to an observer raw roll-axis sensor measurements, commanded and measured yaw-axis wheel momentum storage, measured pitch-axis wheel momentum storage, and external roll-axis and yaw-axis torques, the observer generating a yaw angle estimate and a yaw momentum estimate; (c) subtracting the yaw angle profile from the yaw angle estimate to obtain a difference value; and (d) using the difference value and the yaw momentum estimate to control roll-axis thruster firings to limit spacecraft yaw angle deviations from the yaw angle profile.

Abstract: An attitude control system for a spacecraft which includes a bearing power and transfer assembly. The bearing power and transfer assembly is disposed between a first body and a second body. The first body and the second body are counter-rotated with respect to each other by the bearing and power transfer assembly such that the overall spacecraft momentum about the spin axis of the bearing and power transfer assembly is nominally zero.

Abstract: An attitude sensing system utilizing simplified techniques and apparatus includes a spacecraft control processor which receives signals from an inertial measurement unit and two attitude sensors. The spacecraft control processor calculates a time-varying gain matrix for estimating attitude errors and gyroscope drifts corresponding to the axes of the inertial measurement unit. In special cases where the separation angle between the attitude sensor vectors is less than approximately 10 degrees, the time-varying gain matrix is computed as a fixed gain matrix and a corresponding desensitizing factor.

Abstract: A method for inertially aligning a spacecraft along an axis, comprising the steps of using quaternion feedback control to reorient the spacecraft, and during the step of reorienting, using rate integrating gyroscopes in a pulse rebalance loop. The method operates to orient the spacecraft along an inertial direction of interest by the steps of operating a sensor to provide an initial fix on the inertial direction of interest; repetitively determining a difference between a commanded quaternion and a quaternion estimated based on sensed angular rates; and selectively applying torques to the spacecraft so as to drive the difference towards zero such that a spacecraft vector is aligned with the inertia direction of interest, thereby orienting the spacecraft. One mode of operation maintains the spacecraft fixed in orientation, while another mode of operation rotates the spacecraft about the direction of interest by using a bias-rate blind quaternion propagation technique.

Abstract: The present invention provides a system (200) for determining the ephemeris and attitude for a spacecraft based on optical payload pointing directions and the ephemeris of other spacecraft. An ephemeris determining subsystem (300) obtains ephemeris data (308) for one or more reference spacecraft. Optical payload pointing information (306) is obtained for the optical payload pointed to the reference spacecraft. The spacecraft ephemeris (312) is then calculated with ephemeris determination algorithms (302) based on the ephemeris data (308) and optical payload pointing information (306). Other available information, such as stored results of previous measurements and calculations, time (310), spacecraft attitude (304), information from non-payload sensors and ranging information may be used to enhance the accuracy or decrease the complexity of the ephemeris calculations. Spacecraft attitude can also be determined using reference spacecraft ephemeris data and optical payload pointing information.

Abstract: A device and method for controlling small flows of gas, such as would be used by a satellite (or microsatellite) for orientation thrusters includes a photoetched silicon body etched to provide one or more particular flow paths, and optionally filters, where the flow path is defined by the silicon body and a sealing glass layer bonded thereto. Flow is controlled through the flow path(s) by heating the body to decrease the gas flow.

Abstract: Autonomous slewing of a spacecraft about a desired axis using reaction wheels permits a maximum slew rate without wheel saturation even with one wheel failure. The slew is carried out if the total angular momentum of the spacecraft is less than a momentum storage threshold determined from reaction wheel availability. The momentum threshold may be found as the radius of a sphere inscribed in a polyhedron in momentum space, the polyhedron based on the maximum single wheel capacity and the geometry of the reaction wheel system as well as the reaction wheel availability. The momentum available for the slew is determined from the total angular momentum and the availability of each reaction wheel. The slew rate magnitude and slew direction are based on the available momentum.

Abstract: An automatic apparatus and method that is used to switch actuators, such as momentum wheels, used on a spacecraft without impacting the pointing performance of the spacecraft. The apparatus and method allows an actuator to be automatically deactivated without affecting spacecraft performance such as is caused by a failed actuator. A plurality of local actuator controllers are respectively coupled to a plurality of actuators. A system controller is coupled to the plurality of local controllers and implements a control algorithm corresponding to the present method that determines forces/torques for each of the actuators and outputs force/torque commands to each of the actuators to control the pointing direction of the spacecraft. This is achieved by estimating the drag exerted by or integral control signal produced by each actuator to determine if it is approaching failure.

Abstract: A neural network controller for a pulsed rocket motor tactical missile. The missile includes a fuselage or body, with a propulsion system. The pulsed propulsion system has a need for a logical control of the application of propulsion energy throughout the missile's flight. The controller is trained to provide optimal initiation of individual rocket motor thrust pulses based on tactical information available at various points/times in the missile's flight. The controller training is through use of training cases, in which the network learns to output a specific target value(s) when specific values are input. When trained with a large sample of training cases selected from the multidimensional population of interest, the neural network effectively learns the correlations between inputs and outputs and can predict input/output relationships not previously seen in any training case.

Abstract: A spacecraft attitude control system includes a Momentum Wheel Assembly (MWA) or a Reaction Wheel Assembly (RWA), containing a spinning flywheel, mounted by the use of a mounting bracket to a rotary gimbal which is mounted to spacecraft. The operating MWA/RWA unit is rotated by the rotary gimbal about the gimbal's axis of rotation generating a torque which is provide to the spacecraft, resulting in its movement. The system has the added advantage that the majority of the components are commercially available off-the-shelf products.

Abstract: A method for controlling orbiting spacecraft uploads a plurality of parameters to an onboard processor, the parameters including a plurality of quaternion elements describing an inertial to orbit reference frame, and including radial position, radial velocity and angular rate of the spacecraft. Parameters are input for processing one of a plurality of propagation algorithms, preferably calculating said propagation algorithms with the uploaded parameters, computing enhanced time of day vectors, and computing ground time of day angles from the enhanced time of day vectors for adjusting the payload pointing angle, such as an antenna pointing angle, of the satellite. Preferably, the calculating step comprises integrating an orbital state vector with a second order Runge-Kutta integration algorithm. In addition, enhanced time of day fault processing provides an internal check on integration accuracy and is checked every time of day update.

Abstract: A system for avoiding singularities in a control moment gyro (CMG) array of a satellite uses closed and open loop control of the CMGs for reorientation of the satellite. A control system detects when closed loop control according to pseudo inverse rules will cause a singularity and issues a signal. The CMGs are then controlled open loop to avoid the singularity. The pseudo inverse singularity problem arises where there are more actuators than dimensions in the controlled space. Accordingly, the invention may also be used in a robotic arm manipulator.

Abstract: In a process for identifying an incorrectly measuring sensor which is part of a sensor arrangement on a spacecraft, external directional vectors are measured, relative to external objects, such as the earth, the sun or selected stars, or to external field vectors, such as the earth's magnetic field. Based on actual time and space coordinates of the spacecraft, respective actual external directional vectors are calculated with respect to an inertial system of coordinates, and the angles between these vectors are determined. These angles are compared with corresponding angles which exist between the directional vectors measured by a function of the sensor arrangement relative to a spacecraft-fixed system of coordinates. Based on this comparison a sensor which may measure incorrectly can be identified reliably.

Abstract: The method serves to place a space vehicle, such as a satellite, on a target orbit such as the orbit adapted to normal operation of the space vehicle and starting from an elliptical initial orbit that is significantly different from, and in particular more eccentric than the target orbit.

Abstract: The attitude of a physical platform (62) is altered by a summation of forces from an attitude actuator (74), disturbance forces (80) and random noise (82). Attitude sensors (64) sense the attitude of the physical platform (62) and output measured attitude parameters to a disturbance force effects (DFE) filter (66) and an attitude filter (68). The DFE filter (66) outputs an attitude perturbation command to the attitude filter (68) and a command translator (72). Effects of the attitude perturbation are used by the DFE filter (66) to estimate the effects of disturbances on the physical platform (62). A trigger signal (76) from the attitude actuator (74) is used by DFE filter (66) to select an appropriate gain matrix used in the estimation process.

Abstract: A method and apparatus for autonomous acquisition of attitude in a stellar inertial spacecraft attitude system is disclosed. The present invention uses star trackers, an on-board star catalog, spacecraft steering and inertial sensors to determine spacecraft attitude. The present invention utilizes pattern match and pattern rejection methods and uses multiple stellar snap-shots in conjunction with spacecraft steering and spacecraft inertial measurements to acquire spacecraft attitude. Spacecraft inertial measurements are used to connect multiple stellar snap-shots to provide adequate star information that can be used to acquire spacecraft attitude. In an attitude determination system using star trackers, the star trackers may have a narrow field-of-view or few stars may be available for viewing. The present invention uses pattern matching and pattern rejection on different sets of stars, thereby allowing attitude acquisition when the number of stars in view is small.

Abstract: An apparatus and method for orbit control and maintenance techniques for both individual satellites and for multiple satellites in a constellation utilizing Modern Feedback Control for providing precise autonomous on-board navigation and control. This control system can place any satellite in any orbit position in a constellation, including the acquisition of the initial distribution for the constellation after satellite separation from launched vehicles. This system can also maintain distribution within a constellation, including station relocation and station keeping. Utilizing GPS position information, the orbit state vector is determined and modem advanced multivariable feedback control techniques, for example, linear quadratic Gaussian/loop transfer recovery controllers or optimal H-Infinity Robust Controllers are used to design a navigation and control system.

Abstract: A spacecraft with a reaction wheel system can be autonomously safed by setting the solar wings to continuous tracking, determining a slew rate vector based on the total angular momentum, and slewing the spacecraft using the slew rate vector until commanded to stop autonomous safing. In a typical application, the spacecraft has a reaction wheel assembly with four wheels arranged to form a right regular pyramid. Two reaction wheels on opposite edges of the pyramid form a first pair and the two remaining reaction wheels forming a second pair. The slew axis of rotation is found by determining as a selected pair the first pair if either reaction wheel in the second pair is inoperative, otherwise determining as the selected pair the second pair and determining as the slew axis of rotation the normalized projection of the axes of rotation of the selected pair onto the base. The slew direction is determined by the sign of the total angular momentum component along the slew axis of rotation.

Abstract: Methods are provided for sensing radiation direction over a wide field-of-view. In one process step, radiation is received over a first solid angle and, in response, the direction of that radiation is sensed along a first sensor axis. In a similar process step, radiation is received over a second solid angle and, in response, the direction of that radiation is sensed along a second sensor axis. The first and second solid angles are arranged to spatially intersect over a third solid angle that is a subset of the first solid angle and a subset of the second solid angle. These methods facilitate the determination of inertial planes over a wide field-of-view and the third solid angle facilitates the determination of inertial vectors. Radiation sensor structures in accordance with the methods are also provided.

Abstract: A satellite designed to be spin-stabilized in geostationary orbit which has, coaxial with a spin rotation axis, a satellite body surrounded with a cylindrical solar generator, an apogee maneuver system disposed along the axis and two axially disposed equipments. The apogee maneuver system has opposite one of the equipments at least two thrusters oriented parallel to the axis but offset relative thereto by the same distance. Equi-angularly spaced around the other of the two equipments, the thrusters are connected to a common liquid propellant feed system.

Abstract: Attitude-control methods are provided which eliminate or reduce structural resonances in spacecraft that are excited by momentum wheel imperfections. The methods are preferably practiced with an over-determined attitude-control system which is typically available because spacecraft often carry backup momentum wheels to insure against failure of primary momentum wheels. In a method embodiment, a set of angular-velocity waveforms is selected that substantially realizes a commanded momentum vector when applied to a corresponding set of momentum wheels wherein none of the selected angular-velocity waveforms dwells at a resonant frequency of the spacecraft. The angular velocity of the corresponding set of momentum wheels is then conformed to the selected set of angular-velocity waveforms to realize a spacecraft attitude that corresponds to the commanded momentum vector without exciting the resonance.

Abstract: A system and method for acquiring the Earth by a three-axis stabilized spacecraft in the presence of a significantly time-varying Sun-Earth angle including obtaining an Earth cone described by rotating the nadir vector about the Sun vector, slewing the spacecraft about an axis until the Earth sensor boresight touches an edge of the Earth cone, updating the Earth cone due to the changing Sun-Earth separation angle, performing a spiral coning maneuver about the updated Earth cone until the Earth sensor detects the Earth, and locking onto the Earth so as to hold the Earth sensor boresight coincident with the nadir vector. Additionally, the spacecraft may be rotated about the nadir vector so as to bring the spacecraft into a desired final attitude.

Abstract: Spin-stabilized spacecraft are provided which facilitate simple attitude maneuvers and the use of high-gain antennas and efficient solar panels without the need for complex control systems and an excessive number of thrusters. They include a rotor and first and second spacecraft platforms wherein the rotor and the first and second spacecraft platforms are rotatably coupled together and a spin thruster system is arranged to urge and maintain the rotor in a spacecraft-stabilizing spin about the rotor axis. A first rotary-drive mechanism couples the first spacecraft platform to the rotor and a second rotary-drive mechanism couples the second spacecraft platform to the first spacecraft platform. An attitude thruster is spaced from the rotor axis and oriented to generate an axial thrust component in the rotor for synchronous control of the inertial attitude of the rotor axis.

Abstract: A spacecraft for deployment in geosynchronous orbit about the Earth, comprising six face panels which enclose a compartment containing electronic powering components mounted on the interior surfaces thereof. The panels include opposed north-facing and south-facing panels which do not undergo sun-exposure, remain cool and provide safe interior surfaces for the electronic powering components mounted thereon, and four side panels which are successively rotated into diurnal sun-exposure attitude during which their temperature normally rises so excessively as to damage electronic powering components mounted on the interior surfaces thereof. The invention comprises providing the east-facing and west-facing panels with at least one continuous circulation system containing a heat exchange fluid which absorbs heat from the one of said panels undergoing sun exposure and circulates it to the other of said panels to moderate the temperature of the east-facing and west-facing panels.

Abstract: Solar wing positioning methods are provided which favorably reduce seasonal variation of generated power in a satellite while simultaneously managing the composite system influence that off-pointed solar wing operation imposes on the satellite. The composite system influence includes environmental torques and may also include other system influences such as wing-to-body thermal radiation, thruster plume impingement and antenna/sensor field of view encroachment. In the simplest method embodiment, the solar wings are tilted asymmetrically from a nominal position to reduce seasonal power variations and are further tilted symmetrically to generate a solar pressure torque component which, on a diurnal average basis, compensates a gravity gradient torque component that is substantially generated by the net, off-pointed configuration of the wings.

Abstract: A method for inertially aligning a spacecraft along an axis, comprising the steps of using quaternion feedback control to reorient the spacecraft, and during the step of reorienting, using rate integrating gyroscopes in a pulse rebalance loop. The method operates to orient the spacecraft along an inertial direction of interest by the steps of operating a sensor to provide an initial fix on the inertial direction of interest; repetitively determining a difference between a commanded quaternion and a quaternion estimated based on sensed angular rates; and selectively applying torques to the spacecraft so as to drive the difference towards zero such that a spacecraft vector is aligned with the inertia direction of interest, thereby orienting the spacecraft. One mode of operation maintains the spacecraft fixed in orientation, while another mode of operation rotates the spacecraft about the direction of interest by using a bias-rate blind quaternion propagation technique.

Abstract: A method for controlling the direction of a spacecraft of the type having a controller for calculating thrust forces comprises a plurality of thrusters disposed on said spacecraft in a spaced relationship relative to one another and aligning and locating each of said plurality of thrusters at a predetermined angle on said spacecraft relative to first, second and third orthogonally oriented axes such that the firing of any given pair of thrusters produces a torque about one of said spacecraft axes; and firing of all of said plurality of said thrusters in equal amounts at one time to cause the spacecraft to move in a linear manner along one of said three orthognally disposed axes.

Abstract: Spacecraft attitude is efficiently controlled by utilizing spatial noise and temporal noise in the calculation of gains to a Kalman filter. Spatial noise is modeled in a dynamic fashion so as to provide optimal spatial noise attenuation.

Abstract: Spacecraft stationkeeping and momentum-dumping methods are facilitated by the use of selected diagonal pairs of thrusters which are positioned adjacent to nadir or antinadir spacecraft faces. The methods maintain an elliptical Sun-synchronous orbit, counter triaxiality forces and facilitate momentum-dumping of momentum and/or reaction wheels. They are particularly suited for inclined orbits.

Abstract: Control moment gyros in an array are rotated to reorient a satellite. A pseudo inverse control is employed that adds a term to a Moore-Penrose pseudo inverse to prevent a singularity.

Abstract: Structures and methods are provided to effect satellite maneuvers in the presence of disturbance torques with enhanced fuel efficiency. A thruster control loop is combined with a wheel control loop in which the wheels respond to an estimate of the disturbance torques (e.g., an angular acceleration estimate, a thruster torque command or a filtered thruster torque command) to create a counteracting gyroscopic torque. Simulations of the invention's methods have shown they have the authority of all-thruster control systems and fuel efficiency that rivals that that of all-wheel control systems.

Abstract: The present invention provides an improved intelligent control apparatus and method of a satellite where the orbit and attitude control are executed autonomously onboard the satellite. The satellite makes an intelligent decision whether the satellite should be in normal operations mode or in the contingency mode, and if the satellite is in the normal mode, then attitude and orbit of satellite is controlled autonomously to maintain the predetermined attitude and orbit. If the satellite is in the contingency mode, then the satellite decides whether there is collision danger and executes emergency orbit maneuver automatically if such danger exists. Furthermore the satellite checks for the anomaly functioning sensors and actuators, and discontinues their usage.

Abstract: A sun-referenced safe-hold control system for momentum-biased satellites employs a safe-hold processor responsive to a set of sun sensors to detect attitude errors of the solar wings. Safe-hold processor provides independent control logic which rotates the solar wings to ensure that sunlight is maintained incident on the solar wings to maintain solar power in the safe-hold mode. In addition, the safe-hold processor provides independent control of the momentum wheel to place the spacecraft body in a passively stable nutational state. Passive nutational stability inherent in a momentum-biased satellite about two axes of the spacecraft enables the safe-hold processor to actively control the spacecraft about only one of its axes. The spacecraft safe-hold control system increases the period in which spacecraft health is guaranteed by adding active, closed-loop control of the solar wings.

Abstract: A vibration isolation and precision pointing device, and a related method for its operation, for reducing vibrational disturbances on a payload platform, which is subject to vibration transmitted from a base platform and to other possible vibrational disturbances applied directly to the payload itself or to the payload platform. The invention includes a complementary combination of passive isolation and active isolation in parallel between the base and payload platforms, together with a precision positioning system that greatly reduces vibration at very low frequencies. Each isolation device, of which there are three pairs arranged to damp vibration in three axes, includes, in one embodiment, a passive spring to reduce coupling of vibration at higher frequencies and to fulfill a static load bearing function, and an active actuator element, in the form of a voice coil actuator, for applying active compensation over a selected bandwidth of frequencies below that over which passive isolation is most effective.

Abstract: A system and method for acquiring Sun pointing in a three-axis stabilized spacecraft including slewing at least one solar wing until the Sun is detected, determining an initial Sun vector, performing one or more rotations of the spacecraft body so as to bring the instantaneous Sun vector coincident with a preferred final Sun vector, at least one rotation about an optimal axis, and slewing at least one solar wing to a preferred attitude relative to the Sun. In one embodiment, the optimal axis is chosen so as to minimize the time required to achieve an optimal thermal attitude. In another embodiment, the optimal axis is chosen so as to minimize the time required to align the instantaneous Sun vector with the final desired Sun vector. In a further embodiment, the optimal axis is chosen so as to maintain Earth lock.

Abstract: Apparatus and methods for performing satellite proximity operations such as inspection, recovery and life extension of a target satellite through operation of a "Satellite Inspection Recovery and Extension" ("SIRE") spacecraft which can be operated in the following modes (teleoperated, automatic, and autonomous). The SIRE concept further consists of those methods and techniques used to perform certain (on-orbit) operations including, but not limited to, the inspection, servicing, recovery, and lifetime extension of satellites, spacecraft, space systems, space platforms, and other vehicles and objects in space, collectively defined as "target satellites". The three basic types of SIRE proximity missions are defined as "Lifetime Extension", "Recovery", and "Utility". A remote cockpit system is provided to permit human control of the SIRE spacecraft during proximity operations.

Abstract: Satellite stationkeeping and momentum-dumping methods are facilitated by the use of diagonally-arranged thruster pairs which are positioned on a selected one of a nadir and an antinadir satellite face. A first one of the thruster pairs is directed so that its thruster forces are spaced by moment arms from the satellite's center of mass. Firings of this thruster pair are separated by a momentum-dumping right ascension difference that is chosen to enhance momentum authority. These firings generate momentum-dumping torques and contribute to stationkeeping velocity changes. A second one of the thruster pairs is directed so that its thruster forces substantially pass through the center of mass. Firings of this thruster pair are separated by a stationkeeping right ascension difference chosen to minimize fuel consumption while providing a major portion of stationkeeping velocity changes.

Abstract: One or more deployable thermal panels (24, 28, 70) are actively controlled throughout the orbit of a satellite (20) to provide thermal dissipation. Adjusting the incident angle between the panel (24, 28, 70) and the sun and controlling the flow of fluid through optional flexible heat pipes loads and unloads heat to provide thermal stability for components (62) which have special thermal requirements. An optional antenna panel (70) on a nadir side (64) of the satellite (20) offers an antenna side (74) on one surface and a thermal radiating side (72) on an opposing surface. In addition, thermal panel movements are controlled (96) to provide counter-disturbance torques (140).

Abstract: A feedback motion compensation (FMC) component for use in a spacecraft having a payload. The FMC component includes a controller having sensor data inputs and an open loop dynamics model that is driven by actuator commands to produce a high accuracy attitude estimate suitable for payload motion compensation.