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: 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 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 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 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.

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 method and an apparatus for a multibeam phased array antenna transmission based on heterodyning to produce the RF transmission signals with appropriate phase shift and thereby reducing the effect of certain space constraints in the confined area of the transmitter as higher and higher frequencies of transmission are employed. In the present invention, RF signals at an intermediate frequency, not the ultimate frequency of transmission, comprise the signal frequencies of a beam forming network which provides input to a multiplexed power divider. The power divider outputs the phase shifted signals to an input at each of a number of multiplexed combiners. The output of each combiner is fed to a mixing device which then shifts the input frequency to a higher frequency, using an appropriate local oscillator signal. The mixer outputs are coupled to separate power amplifiers, whose outputs are fed to the elemental radiators.

Abstract: An onboard star tracking system is used to provide continuous attitude and orbital position data independent of the image generating instruments. Such data is instantaneously and continually supplied to the onboard computer which translates such information into mirror position coordinates which is added to the mirror position set based on estimated data from the ground control. An error signal is generated which is used to further adjust the position of the mirror.

Abstract: The invention relates to a Common Direct Broadcasting Service (CDBS) system for a communications spacecraft. The CDBS system comprises N uplink antennas for receiving uplinks from terrestrial transmitting stations. Each uplink includes left-hand circular polarized (LHCP) signals and/or right-hand circular polarized (RHCP) signals. The LHCP signals and the RHCP signals have frequencies within predetermined channels of a first and/or second predefined frequency band. The CDBS system also comprises means for separating the LHCP signals of the uplinks received by each uplink antenna from the RHCP signals of the uplinks received by each uplink antenna. The CDBS system further comprises a plurality of receivers for converting the separated LHCP signals and RHCP signals of the uplinks to first signals and second signals, respectively, of the uplinks. The first and second signals have frequencies within channels of a third and/or fourth predefined frequency band.

Abstract: A lens is fabricated of an array of parallel rod-shaped dielectric waveguides extending from a generally planar front surface of the array, this front surface constituting a front surface of the lens, to a concave back surface of the array, this back surface constituting a back surface of the lens. The wavguides vary in length, from a maximum length at an outer region of the lens to a minimum length at a central region of the array, to provide the concave back surface. The back lens surface envelops a receptor of radiant energy located at a focus of the lens. This configuration of lens provides an increased spherical angle of impingement of the incident radiation upon the receptor.

Abstract: A broadband linearizer for use with a power amplifier. The broadband linearizer includes a broadband linearizer bridge, a preamplifier/attenuator, a post amplifier/attenuator, and a control circuit. The broadband linearizer bridge includes a power divider and a power combiner interconnected by linear and nonlinear arms. The linear arm has a phase shifter, a passive equalizer, and a first delay line that are serially coupled together. The nonlinear arm has a distortion generator, an attenuator and a second delay line that are serially coupled together. The control circuit controls respective settings of the broadband linearizer bridge, preamplifier/attenuator and post amplifier/attenuator. The control circuit provides bias circuitry and sends command and telemetry signals to control operation of the broadband linearizer. The broadband linearizer provides for independent, flexible gain and phase control that can mate with different kinds of power amplifiers having various gain and phase performance.

Abstract: A precise, spacecraft camera image navigation and registration system and method wherein a computer 36 on-board the spacecraft and a ground system comprising at least two ground stations precisely compute image navigation and registration data from precise data measurements. The computer on-board the spacecraft (spacecraft control system) uses precise star tracker, gyro, and earth sensor attitude data to precisely point the spacecraft and the camera. The ground system utilizes precise star measurement data from the camera and range data from the ground stations time tagged with GPS precise clock data. The ground system uses these precise measurements to determine precise orbit and attitude coefficients and uploads these coefficient to the spacecraft. The computer on-board the spacecraft uses these precise coefficients to generate and apply precise signals to compensate for slow orbit and attitude variations and register camera images in real time.

Abstract: A battery system for an body stabilized satellite traveling in a geosynchronous orbit comprises east and second battery modules and similarly facing radiators for discharging beat to deep space. Heat conduction arteries connect each battery module to its associated radiator. An east thermal switch is operable for thermally connecting the first battery module to and from the east facing radiator. Similarly, a west thermal switch is operable for thermally connecting the second battery module to and from the west facing radiator. A computer selectively operates the east and west thermal switches such that, in one instance, for a time between the satellite's emergence from the earth's shadow and its position nearest the sun, the respective thermal switches thermally connect the first battery module to its radiator while thermally disconnecting the second battery module from its radiator.

Abstract: A spacecraft includes a plurality of thrusters mounted at predetermined locations on a spacecraft structure, individual ones the plurality of thrusters being fired for generating a torque about a desired axis. The firing of a thruster is partitioned into two firings that are offset in time by an amount .DELTA.t, wherein .DELTA.t=(1/2).times.(1/F).times.SF, where F is a dominant modal frequency, in Hertz, for any particular axis (nominally the 1st mode) of the spacecraft structure, and where SF is a scale factor that is adjustable about the frequency. In a presently preferred embodiment the thruster is a low thrust thruster that is mounted on a solar array panel, and the thrusters are fired in pairs.

Abstract: For a switching of a magnitude of system gain in the driving of a load by a control system, a method of inhibiting formation of switching transients has a step of distinguishing between an estimate of a plant state, such as the attitude of a spacecraft, and an integral control state which allows the control system to provide actuation in response to long term disturbances, such as solar pressure, in operation of the system. In the case of a feedback configuration to the system with controller in a forward branch and an estimator in a feedback branch, a loop error signal serves to drive an actuator of the load via the controller. The method includes a further step of evaluating a portion of a controller input signal which is exclusive of an integral control state and which comprises a difference between a desired state and an estimate of the plant state.

Abstract: An antenna, forming a part of an antenna system, is suitable for use on a communication satellite encircling the earth, and has a reflector illuminated by a set of feed elements wherein one of the feed elements generates a primary beam. The reflector is shaped to establish a specific configuration of the beam, and, upon illumination of the earth, there results a specific shape to the beam footprint. A mechanical positioning device connects the antenna with a body of the spacecraft for adjusting an orientation of the feed antenna and its beam relative to the body of the spacecraft. Control circuitry for adjustment of signal strengths and phase shifts of signals sent to respective ones of the feeds is accomplished by electronic circuitry including a memory which stores coefficients employed in the operation of variable power dividers and variable phase shifters of a feed network supplying electromagnetic signals to the feed.

Abstract: A very large number of small electric cells are assembled electrically in parallel into a cell module to provide a large ampere-hour capacity and, in turn, multiple cell modules are series connected into a spacecraft battery having the power necessary to satisfy the requirement of the spacecraft. The invention provides for (a) three-dimensional packaging of parallel cells, (b) rejecting the internal heat from such a package, and (c) providing redundant electrical fuse protection for the internal cell array. Thus, at least first and second layers are provided, each being of plural commonly aligned, parallel bussed, electric cells, each cell including opposed ends and an outer peripheral surface. The cells are disposed in a planar side-by-side relationship, and each layer includes a plurality of outermost cells encompassing an interior region. The layers are connected electrically in parallel and are laterally coextensive and aligned in an end-to-end relationship.

Abstract: An antenna is shaped to provide a predetermined contour and is mounted for universal movement on its support. An electronically controlled drive mechanism is operatively associated with the antenna to rotate the antenna to preselected positions corresponding to specific target locations. A fixed feed horn excites the antenna to generate a first radiation pattern which conforms to the shape of a primary desired target location when the antenna is moved to a first position and a second radiation pattern which conforms to the shape of a secondary desired target location when the antenna is moved to a second position. By further designing the antenna shape, multiple contoured beams for multiple target locations are obtained.

Abstract: A technique of operating a lithium-ion (Li-ion) battery is proposed for maximizing battery life. In a first instance, this technique calls for charging the battery at a lower temperature than the temperature at which discharge begins. Preferably, the battery is charged at a temperature T.sub.1 in the range between about +5.degree. C. and -20.degree. C.; and discharged at a temperature T.sub.2, in the range of about +5.degree. C. to +30.degree. C., T.sub.2 being higher than T.sub.1. In another instance proposed by the invention, the battery is charged to an elevated state of charge which is above an initial state of charge at a temperature T.sub.1 between about +5.degree. C. and -20.degree. C. which is lower than a temperature T.sub.2, in the range of about +5.degree. C. to +30.degree. C., at which discharge begins.