Abstract: A three-axis stabilized spacecraft having roll, pitch, and yaw axes and when on station in orbit about the earth having a north face and a south face is equipped with a first and second thruster which may be electric thrusters. A first support device mounts the first thruster adjacent the north face and the first thruster is positioned a spaced distance away from the north face in a first direction parallel to the pitch axis and spaced from the pitch axis in a second direction normal to the pitch axis. A second support device mounts the second thruster adjacent the south face, the second thruster being positioned a spaced distance away from the south face in a third direction opposite the first direction and spaced from the pitch axis in the second direction. A gimbal mechanism pivotally mounts the first and second thrusters on the first and second support devices, respectively, for selectively positioning the attitude of the first and second thrusters.

Abstract: A charge control circuit for use with lithium ion satellite batteries that provides for both charge control and cell bypass features. The charge control circuit reconfigures the battery from a series array of cells to a parallel array of cells using switches (that are part of the battery) in order to implement the cell bypass function. The switches are preferably implemented using low resistance mechanical relays to lessen the thermal dissipation of the circuit. The charge control circuit minimizes the amount of current passing through the parallel battery circuit by breaking the battery down into sub-modules for purposes of charging, and using distributed low voltage power supplies for charging. The charge control circuit may also implement sequential charging of the battery along with bus cross strapping to ensure that the satellite electrical bus is always supported by one battery during battery recharging.

Abstract: A solar cell assembly with current limiting protection comprises a rectangular planar solar cell having four corner locations including first and second opposed surfaces and a beveled edge at one of the corner locations. Parallel spaced longitudinally extending conductors are provided on a first opposed surface and a metallic coating overlies an entire second opposed surface. Interconnect members mount a protective bypass diode, electrically intermediate and in series with the first and second conductor members, on the solar cell in a mutually coplanar relationship proximate to but spaced from the beveled edge, accommodating relative in-plane motion between the bypass diode and the solar cell.

Abstract: Two helical resonator filters for applications in wireless and satellite communication systems. The present invention provides for single mode and dual mode microwave filters that employ evanescent waveguide cavities loaded with helical resonators. The structure of the present invention provides for a high Q factor in a miniature package. Two helical resonator filters are well adapted for use in wireless and satellite communication systems. The present invention provides for miniature filters utilizing single mode, high dielectric constant material loaded helical resonators, as well as higher order dual mode helical resonator loaded cavities. Both configurations can be used to realize advanced filters with non-adjacent coupling. The helical resonators may be loaded with high dielectric constant materials or ferrite materials for additional miniaturization and tunability. Either voltage or current tuning may be provided by the single mode and dual mode microwave filters.

Abstract: In drive circuitry for powering an arc jet or ion engine aboard a spacecraft carrying solar panels, a start-up circuit interconnects an array of series-parallel connected solar panels to establish and maintain an arc and plasma in the engine. In the start-up circuit, an electric switch is placed in parallel with an electrode assembly of the engine. One terminal of the engine connects directly with the solar panel array, and another terminal of the engine connects via an inductor to the solar panel array. A capacitor connects across terminals of the solar panel array. A series connection of solar panels increases the voltage from that which is available from a single panel. Conduction of current from the solar panel via the inductor is initiated by the switch to store magnetic energy within the conductor. Thereupon, upon an opening of the switch, the inductor produces a relatively high voltage which strikes an arc in the engine.

Abstract: A battery cell bypass module comprises a sensor for detecting an operating condition of a battery cell such as voltage or temperature and a controller connected across the battery cell of a lithium ion battery, for example, and having a conductive mode and a normally non conductive mode. The controller is operable to change to the conductive mode when an operating condition of the battery cell exceeds a predetermined value to thereby shunt current around the battery cell. The sensor may be a temperature transducer such as a thermistor for measuring battery cell temperature and a cell temperature comparator such as an operational amplifier is operable to generate a temperature excessive signal when the signal from the temperature transducer exceeds a predetermined value, the controller then being operable to change to the conductive mode and thereby shunt current around the battery cell.

Abstract: A method and system is disclosed for imaging a celestial object, typically the Earth, with a spacecraft orbiting the celestial object. The method includes steps of (a) operating an imager instrument aboard the spacecraft to generate data representing an image of the celestial object; (b) processing the image data to derive the location of at least one predetermined landmark in the image and a location of edges of the celestial object in the image; and (c) further processing the detected locations to obtain the attitude of the imager instrument. The method includes a further step of outputting the image and the imager instrument attitude to at least one end-user of the image, and/or using the imager instrument attitude to revise the image before outputting the image to the at least one end-user of the image. The generated data preferably represents a one half frame image, and the steps of processing and further processing thus occur at a one half frame rate.

Abstract: A software-controlled select and test system for use with a spacecraft. The system reduces the assembly, integration, test time and improves performance of the payload and spacecraft by optimizing the performance using standardized algorithms. The system also reduces the DC power required by the spacecraft, and the thermal dissipation, battery size, solar array size and mass of the spacecraft. This is achieved by optimizing traveling wave tube amplifiers for each channel instead of meeting minimum power requirement over the entire range, wherein most channels have excess power. A serial interface adapter performs the optimization functions via software.

Abstract: A system for managing the operation of a battery such as a lithium ion battery having a plurality of serially connected individual cells comprises a bypass module electrically in parallel with each individual cell or, alternatively, with at least one of the cells or alternatively again with an individual cell and its associated grouping of one or more parallel cells. The module includes a sensor for detecting an operating condition of its associated cell and a charger operable for charging the cell. A charge controller is electrically connected with each bypass module and is operable in response to an operating condition of a cell detected by the sensor which is outside a predetermined range of magnitudes to change the bypass module to the conductive mode and thereby shunt current around the battery cell, while leaving unaffected each of the remaining cells.

Abstract: An onboard star tracking system is used to provide continuous attitude data based on a fixed star catalog. An orbital position reference for the sensed star data is estimated from uploaded data. The attitude is calculated based solely on the star sensor data referenced to the estimated orbital position and compared to mission attitude to generate an attitude adjustment.

Abstract: Self-latching deployment apparatus for a multi-paneled solar array comprises at least first and second in-line panels pivotally connected together for rotation about an in-line hinge axis between stowed and deployed positions. A first deployment and locking mechanism maintains the in-line panels in the deployed position. First and second side panels are pivotally attached to opposite edges of the second in-line panel for rotation between stowed and deployed positions about secondary and tertiary hinge axes, respectively, transverse to the in-line hinge axis between the first and second in-line panels. A first restraint mechanism is engaged with the first side panel to temporarily overpower a drive mechanism for the first side panel and thereby temporarily maintain the first side panel in the stowed position but becomes disengaged from the first side panel when the first and second in-line panels reach the deployed position to enable the first side panel to move to the deployed position.

Abstract: A thinned multiple beam phased array antenna which includes, in a sending array configuration, an antenna element, beam forming network, feeding circuits, a phase and gain controller, and a phase control algorithm storage unit. A feeding circuit is coupled to an associated antenna element and the beam forming network, and passes a beam forming signal between the antenna element and the beam forming network. The antenna element preferably includes a plurality of radiators and a plurality of band pass filters, wherein a band pass filter is dedicated to each radiator. The beam forming network preferably includes a stripline power divider and a power distributor. The feeding circuits preferably include a plurality of impedance-matching isolators, a plurality of solid state power amplifiers, a plurality of n:1 signal combiners, a plurality of monolithic microwave integrated circuits (MMICs), and a plurality of phase shifters.

Abstract: A series of solar panels are assembled into an array for use as a source of solar power for a satellite. The panels are designed with diminishing thickness from the yoke to the tip to obtain a constant stress distribution.

Abstract: An extended band, multiple channel multiplexer 10 well-suited for use with satellite communications systems. The multiplexer utilizes a low attenuation, contiguous diplexer 18 containing contiguous diplexer filters 18a to combine two sections 11a, 11b of the multiplexer respectively containing contiguous channel filters 14a, 14b. The multiplexer comprises low attenuation, contiguous diplexer filters 18a tuned in tandem with channel filters 14a, 14b to provide contiguous multiplexing. This approach takes advantage of the constructive interaction between these filters to realize an equivalent contiguous multiplexer. This enables realization of a wide band contiguous multiplexer, which heretofore was impossible to tune. The contiguous diplexer eliminates spurious modes of the channel and diplexer filters, spurious waveguide modes, and out of band interaction between the two portions of the multiplexer. Therefore, tuning of the multiplexer is possible.

Abstract: Solar panels having a lightweight honeycomb core as a support for an upper surface array of solar cells. The upper surface of the core is bonded to an upper insulation/faceskin laminate, and the lower surface of the core is bonded to a heat dissipation/faceskin laminate having an undersurface for absorbing heat from the solar cells and dissipating the heat into space for cooler operation and increased power efficiency of the solar panel. The invention resides in the use of a heat dissipation layer of curable resin and carbon powder having increased heat-emission properties.

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.

Abstract: A pre-distortion type linearizer circuit for use in linearizing the performance of power amplifiers such as traveling wave tube and solid state power amplifiers. The linearizer circuit comprises linearizer bridge that includes a phase shifter and a fixed delay in a linear arm, and a distortion generator and an attenuator in a nonlinear arm. The output of the linearizer bridge is coupled through an output amplifier and an output attenuator. The RF output signal from the linearizer circuit is coupled to the power amplifier. A control circuit receives on and off input command signals, and outputs a bilevel telemetry signal that is used as a mode indicator for ground command control. The control circuit adjusts settings of the linearizer bridge, and adjusts gain and attenuation settings of the output amplifier and output attenuator. All circuits of the linearizer circuit may be integrated onto a single alumina substrate, for example.

Abstract: A method in accordance with this invention for maintaining a spacecraft in a desired orbital configuration, comprises the steps of: (a) recording a history of yaw momentum stored in momentum wheels; (b) estimating an average inertial torque and momentum over a previous time interval (such as one day); (c) determining a desired change in inertial torques using PID control law; (d) commanding a change in satellite trim tab and solar array position from a desired change in solar torque; and (e) slewing the trim tab and solar array a desired amount.

Abstract: A spacecraft ground loop controller (GLC), located on the Earth, interfaces with a satellite ground station receiving spacecraft telemetry from the downlink baseband equipment and automatically sending spacecraft commands through the command uplink baseband equipment to control the attitude of an orbiting spacecraft and achieve partial orbit control using commanded thruster firings and magnetic torquer polarity and magnitude. A cooperative approach of using all available thrusters, of both the primary and redundant strings, provides greater fuel savings.

Abstract: A spacecraft battery system is of a mass efficient design without voltage regulation of the battery resulting in increased satellite reliability, lower bus voltage noise and EMI susceptibility, and lower cost. It calls for a battery which includes a plurality of electrically connected cells, each of the cells having a positive electrode, a graphitic negative electrode, and a dielectric separator intermediate the positive electrode and the graphitic negative electrode and an unregulated bus electrically connecting the battery and a load for the operation thereof. The battery is preferably a lithium ion battery in which the material of the positive electrode is selected from the group consisting of Li.sub.x Mn.sub.2 O.sub.4, Li.sub.x NiO.sub.2, Li.sub.x CoO.sub.2, Li.sub.x Co.sub.y Ni.sub.1-y O.sub.2 where x and y >/=1 and in which the material of the positive electrode is selected from the group consisting of petroleum coke, graphite, and SnO.sub.2.