Abstract: Heat transfer systems and methods 30 for use on a spacecraft that use a loop heat pipe to transfer heat from a remotely located heat source to a thermal radiator or other heat dissipating apparatus. The loop heat pipe is a two phase heat transfer device that has an evaporator coupled to the heat source and a condenser coupled to the thermal radiator or other heat dissipating apparatus. The loop heat pipe comprises thin walled tubing to connect the evaporator and condenser. The thin walled tubing allows the loop heat pipe to be flexible.

Abstract: Dynamic resource allocation that provides differentiated services over a broadband communication network. The system comprises a gateway that interfaces to an Internet service provider or corporate network, a local area network edge device, a satellite that provides a communication link between the gateway and the local area network edge device, and one or more personal computers coupled by way of a network to the local area network edge device. The dynamic resource allocation system supports differentiated services with different levels of priority and comprises an Internet protocol network that includes a classifier for identifying specific types of messages, and a dynamic assignment/multiple access (DAMA) communication protocol for transmitting data over the system.

Abstract: A spacecraft heat dissipation method, and a spacecraft having an improved thermal radiator system that uses two-sided deployable thermal radiators that dissipates heat from both front and back surfaces thereof. The use of the two-sided deployable thermal radiators enables the thermal radiator system to have approximately 50% more heat dissipating capability than a system with just one surface exposed to dissipate heat. The spacecraft includes a body, one or more solar arrays, and the present radiator system which comprises opposite facing fixed payload radiators that are thermally coupled to selected ones of the deployable radiators by way of heat pipes. In an exemplary method a spacecraft is configured to have a body, one or more solar arrays opposite facing fixed payload radiators, and one or more two-sided deployable radiators selectively coupled to the fixed payload radiators. The spacecraft is launched into orbit.

Abstract: A momentum wheel configuration that may be used on a spacecraft having a momentum bias that prevents zero wheel speeds. The momentum wheel configuration comprises three or more momentum wheels. The momentum wheels are oriented such that their wheel axes are not parallel to each other. The momentum wheels are oriented such that their axial momentum vectors are not coplanar. None of the momentum wheels have their wheel axis parallel to the momentum bias direction of the spacecraft. No two of the momentum wheels are oriented such that their axial momentum vectors are coplanar with the momentum bias direction of the spacecraft.

Abstract: A spacecraft embedded in a reference frame rotating relative to inertial space. The spacecraft generally includes actuators for maneuvering the spacecraft with respect to the reference frame, an attitude measurement device that measures the pitch and roll attitude of the spacecraft with respect to the reference frame, a control device adapted to keep the roll and pitch angles of the spacecraft close to the commanded roll and pitch angles, and a harmonic torque estimator adapted to read the commanded angular velocity of the spacecraft relative to an inertial frame, read momentum wheel speeds, read known predicted external torques and combine angular velocity, measured wheel speed and known external torque to produce an estimated observable periodic torque.

Abstract: Thermal apparatus that reduces passive intermodulation products generated on a satellite or other spaceborne vehicle. Exemplary passive intermodulation free thermal blankets comprise a reflector stack including multiple polyimide layers with metallized film on one side thereof, a binding layer that secures the reflector stack together, and an outer cover layer that wraps around the binding layer and reflector stack to cover an outer surface of the thermal blanket and form a hem on an inner surface of the thermal blanket. Multiple small thermal blankets or patches may be bound together using grounding inserts and polyimide tape to form a quilt-like assembly. The quilt-like assembly is enclosed by an outer cover layer that wraps around the multiple patches to cover one surface thereof and form a hem on an opposite surface thereof.

Abstract: An improved soft switched AC power distribution system for minimizing electromagnetic interference and AC losses in an AC power distribution system. The improved AC power distribution system comprises a flyback transformer comprising a primary winding and at least one intermediate secondary winding. A synchronization control circuit is connectable to the primary winding while at least one load transformer is connectable to the at least one intermediate secondary winding. The at least one load transformer connectable to the at least one intermediate secondary winding is connectable via an EMI shielded connection with controllable voltage and current rise times.

Abstract: A communications satellite payload provides for efficient communications between user devices, such as hand held cellular telephones, and terrestrial gateways that may be connected to world-wide public telephone and telegraph (PTTs) networks. The satellite payload simultaneously supports a plurality of independent antenna beams, for example 12 or 16 beams, on both the uplink and downlink for user devices employing full duplex communications. The satellite payload furthermore supports an identical number of full duplex channels between a terrestrial gateway and the satellite. The communications satellite payload is carried by one satellite of a plurality of such satellites in a low earth orbit (LEO) constellation to provide world-wide communications. Downlink beam forming occurs prior to final amplification of transmitted signals, thereby reducing losses within the beam forming equipment.

Abstract: A bilateral power converter (10) for a satellite power system comprises a battery (12), an inductor (14), a switching means (18, 20), and a controller (16). The battery (12) preferably has a first and second terminals. The inductor (14) is coupled to the first terminal of the battery (12) and the switching means (18, 20). The switching means (18, 20) selectively couples the second end of the inductor (14) to a bus (28) or to ground ill response to a control signal. The controller (16) monitors the bus (28) voltage, current flow to the battery (12) and the current flow through the switching means (18, 20). The controller (16) also receives control signals from the satellite's computer (13) and automatically regulates the voltage on the bus (28) by adjusting the duty cycle of the signal output by the controller (16) to the switching means (18, 20).

Abstract: A spacecraft (201) maintains its north-south positioning by using one of two pairs of single-gimballed throttled thrusters (221-224) on a face of the spacecraft (201). The throttles (118) and gimbals (116) of the thrusters (221-224) are controlled to produce torques on the spacecraft (201) that will maintain a desired attitude for the spacecraft (201) while simultaneously desaturating the momentum stabilizing wheels ( 120, 121 ) of the spacecraft (201).

Abstract: An electrochemical energy cell for use in a satellite or other environment where failure of the cell can cause great harm or inconvenience is disclosed in which the cell operates within a sealed pressure vessel in which a gas is maintained under high pressure and which is subject to bombardment by meteorites which can cause holes or cracks in the pressure vessel, thereby rendering the cell incapable of conducting an electric current therethrough, which in turn renders a battery of such cells useless. To prevent this, a pressure sensitive switch is provided in each cell which is connected in a circuit which by-passes the current generating discs of the cell when the switch is closed. The switch is normally maintained open by the pressure within the vessel, and is biased to close in the event that the pressure in the vessel drops below a predetermined minimum, so that the damaged cell will still conduct current therethrough to maintain the integrity of the entire battery.

Abstract: A push-push microwave oscillator has two branch oscillators fabricated of a transistor and transmission line elements extending from terminals of the transistor, and a resonator which is fabricated of an annulus of superconductor material and serves to phase lock oscillations of the two branch oscillators. The superconductor material is a composite of a rare earth element and copper oxide such as yttrium-barium-copper oxide. A first transmission line in each of the branch oscillators extends past the resonator with a spacing to provide for electromagnetic coupling between the branch oscillator and the resonator. A second transmission line in each of the branch oscillators has a length equal to approximately one-quarter wavelength of the oscillation frequency to tune the branch oscillator to a common oscillation frequency.

Abstract: An active transmit phased array antenna system for generating multiple independent simultaneous antenna beams to illuminate desired regions while not illuminating other regions. The size shape of the regions is a function of the size and number of elements populating the array and the number of beams is a function of the number of beam forming networks feeding the array. All the elements of the array are operated at the same amplitude level and beam shapes and directions are determined by the phase settings. The active transmit phased array antenna includes a plurality of antenna elements disposed in a hexiform configuration. Each antenna element is identical and includes a radiating horn capable of radiating in each of two orthogonal polarizations. The horn is fed by a multi-pole bandpass filter means whose function is to pass energy in the desired band and reject energy at other frequencies. The filter means is coupled into an air dielectric cavity mounted on substrate.

Abstract: Digital signals are converted to phase and amplitude altered, periodic, analog signals and emplaced on an output link. The system is adaptive and includes a plurality of simple quadrature phase shift keying modulators, each modulator having a plurality of controlling digital inputs, the states of which determine which of a plurality of phase displaced signals will be outputted. A local oscillator provides a periodic sinusoidal signal to each QPSK modulator. Summing circuits combine the outputs of the modulators so as to produce a constellation of phase and amplitude-displaced output sinusoidal signals. A processor/mapper combination enables conversion of a first set of digital inputs to a different set of digital outputs in accordance with a control input. Thus, the processor enables the alteration of the constellation of outputs in accordance with a control input, which may be indicative of the condition of a transmission facility.

Abstract: A bilateral power conversion circuit (30) includes a current sensor that includes a resistance (R.sub.s) coupled in series between a first terminal of a switch (SW2) and a ground potential. The current sensor has an output for providing an over-current signal to an input of a control circuit (24) during a time that the circuit is sinking current from a load and also during a time when the circuit is sourcing current to the load.