Abstract: A system and computer-implemented conflict resolution method for resolving air traffic conflicts involving a plurality of aircraft. The system may comprise an air traffic control system having a computer that implements a conflict resolution method, and a radar coupled to the traffic control system that provides position and velocity information for each aircraft. A communication subnetwork is used to communicate between aircraft and the traffic control system. Each aircraft may have a computer that implements the conflict resolution method, and a data link for transferring position and velocity information between the aircraft and the traffic control system over the communication subnetwork. Thus, either the aircraft, or the air traffic control system, or both implement the present method.

Abstract: An umbrella-like antenna reflector assembly for use on an orbiting spacecraft. The reflector has a main rib and a plurality of secondary ribs each connected to a hub assembly by a respective hinge mechanism such that activation of the hub assembly causes the reflector to move between collapsed and opened configurations. The reflector further has a mesh member attached to the ribs. A deployment boom connects the main rib of the reflector to the spacecraft. The deployment boom is operable with the main rib and the spacecraft to move the reflector between a collapsed and stowed configuration proximate the spacecraft and an open and deployed configuration outside the spacecraft. The storage profile is sufficiently slim to permit launching of a 6-25 meter diameter reflector attached to a full-sized spacecraft on one or more commercially available launch vehicles without the need for mid-rib hinges. A feed assembly is connected to the spacecraft.

Abstract: A collector for collecting an electron beam in a traveling wave tube is disclosed. The collector includes at least one collector stage provided with two annularly arranged stage segments. The stage segments include overlapping end portions to prevent impingement of electrons of the electron beam against an isolator surrounding the collector stage. The stage segments facilitate the realization of transverse electric field distributions from one stage segment to the other stage segment within the collector by application of selected voltages to the stage segments.

Abstract: A coaxial "M" switch having three coaxial input connectors (A, B, C) spaced evenly from each other, and three coaxial output connectors (1, 2, 3) identically arranged. In a cylindrical barrel embodiment (10) the input and output connectors are located at opposite ends of a cylindrical configuration. In one planar embodiment (30), the input and output connectors alternate with each other and define a hexagonal configuration (40). In another planar embodiment, the input connectors (A, B, C) define an inner triangular configuration (70) that is surrounded by the output connectors (1, 2, 3) defining an outer triangular configuration. In each embodiment, reeds are actuated in predetermined configurations to define three switch positions.

Abstract: Electrostatic propulsion systems for spacecraft include a plurality of electrostatic thrusters that are continuously coupled to power forms of a power supply system. Ionizable gas is fed to a selected one of the thrusters to selectively initiate the thrust of that electrostatic thruster. In other embodiments, heater power forms are coupled only to the selected thruster to reduce power consumption and increase cathode lifetime. The propulsion system has a reduced complexity and is especially suited for spacecraft in which only one thruster is ever fired at a given time.

Abstract: A tracking analog-to-digital converter (ADC) which incorporates an input device, such as a superlattice, which produces a pulsating output current corresponding to the voltage level of an analog input voltage and an encoding device to provides a unique digital code which can be read to yield an approximation of the analog input voltage level. By simultaneously tracking the analog input voltage, the device operates at higher speeds than previously attainable. The resolution of the new ADC is increased by composing the input device to respond to narrow voltage ranges. When the input device is a superlattice, narrow response ranges are accomplished by composing the superlattice to have an increased number of resonances or by vertically stacking a plurality of superlattices.

Abstract: A ceramic-polymer composite material such as part of a microelectronics package is formed of a ceramic mixture of aluminum nitride and boron nitride, and a low-loss polymeric material. The amount of aluminum nitride is preferably from about 50 to about 90 weight percent of the ceramic mixture, but the relative amounts of the two ceramics may be adjusted to achieve thermal expansion and thermal conductivity properties required for a particular application. A mixture of the ceramics and uncured thermosetting polymeric resin is formed, pressed into the shape of the microelectronics base and/or lid, and heated (either concurrently or subsequently) to compress the mixture and cure the polymer.

Abstract: A face sheet is bonded to a porous core by contacting adhesive to the porous core at the bonding face, placing a screen stripping sheet overlying the adhesive, and pressing on the stripping sheet while heating the core and adhesive. The adhesive is thereby forced against the exposed portions of the cell walls at the bonding face and into the interstices of the stripping sheet. The excess adhesive not contacting the exposed cell walls is removed by cooling the stripping sheet and adhesive, and peeling the stripping sheet and excess adhesive from the core. A face sheet is bonded to the porous core with the remaining adhesive that adhered to the exposed cell walls.

Abstract: A method and system for use as a modeling tool accurately estimates propellant remaining aboard a spacecraft at the completion of a transfer orbit by iterating mass flowrate in a linear optimized fashion until the difference between a predicted .DELTA.V and observed .DELTA.V is minimized. Actual flight pressure telemetry data is used to calculate a corresponding mass flowrate which must have been produced by a liquid apogee motor (LAM) for the spacecraft to reach the desired position. A thruster specific impulse value (ISP) is derived from ground test data to allow computation of the amount of propellant consumed during transfer orbit. When this value is subtracted from the known initial propellant load, the propellant remaining at the beginning of life (BOL) of a satellite can be calculated.

Abstract: A reconfigurable multiple beam array antenna for transmitting beams includes a reflector and radiating elements for feeding beam signals to the reflector. The array antenna includes a reconfigurable beam forming network having a plurality of dividers, a plurality of adjustable phase shifter and attenuator pairs, and a plurality of combiners to form beam signals from beam signals input to the beam forming network. A first hybrid matrix formed by an association of couplers is connected to the beam forming network for receiving the beam signals. Amplifiers receive and amplify the beam signals from the first hybrid matrix. A second hybrid matrix formed by an association of couplers is connected to the amplifiers for receiving the beam signals. The second hybrid matrix provides the amplified beam signals to the radiating elements for the reflector to transmit beams.

Abstract: A spacecraft traveling in a volume of space receiving radiation from a radiation source and having 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 body rotates about a rotation axis, T, which defines a nonzero angle of inclination .lambda. relative to the Z axis. A radiation receiving element is rotatably attached to the spacecraft body along an axis, S. A control system is employed on the spacecraft for rotating the spacecraft body about the rotation axis T by an angular amount .gamma. and rotating the radiation receiving element by an amount so that the radiation receiving element is normal to the radiation source.

Abstract: A reconfigurable multiple beam phased array antenna has radiating elements arranged in a planar array and variable phase shifters. Each one of the phase shifters is connected to a respective one of the radiating elements. The array antenna further includes a beam forming network for forming spot and regional beam signals. The beam forming network forms a regional beam signal from a combination of spot beam signals. The beam forming network has two dimensional stacks of Rotman lenses provided with a first set of ports. Each one of the first set of ports is connected to a respective one of the radiating elements with. The Rotman lenses generate frequency invariant spot beam signals which are communicated between the radiating elements and the Rotman lenses via the first set of ports for transmission and reception of spot beams and regional beams by the radiating elements. The phase shifters are adjusted to steer the spot and regional beams to desired locations.

Abstract: A traveling wave tube and method of operation is disclosed. The traveling wave tube includes a slow wave structure such as a helix member provided with input and output ends and located within a tube member. An electron gun assembly is adjacent the input end for injecting electrons as an electron beam along an axial path through the helix member. A magnetic focusing device generates a magnetic field having a given strength to confine the beam to the axial path. The given strength of the magnetic field is sufficient to confine the beam only when the power level of the microwave input signal is selected such that the given power level of the microwave output signal is at least 6 dB lower than the power level of the microwave output signal at saturation. Boron Nitride (BN) supporting rods are engaged between the tube and helix members for supporting and transferring heat away from the helix member.

Abstract: Antenna apparatus having a fixed dipole and a rotating cup. The cup is formed from a cylindrical conductor shorted at its base to a conducting plate. The fixed dipole is recessed within the cup and has a coaxial transmission line feed that penetrates through a base plate of the cup and is coupled to the dipole. The present invention achieves beam scanning by mechanically rotating only the cup, and wherein the dipole and feed remain fixed. The antenna may further comprise a second fixed dipole oriented orthogonal to the fixed dipole. The dipole feed may be a hybrid coupler network coupled by way of a plurality of coaxial transmission line feeds and a four-post balun to the fixed dipoles. The first and second crossed dipoles lie in a plane that is generally orthogonal to a central axis of the antenna. In an alternative embodiment, the dipole feed may be a turnstile, crossed-dipole feed. In another embodiment, a transmission line feed is directly coupled to a crossed dipole having asymmetrical arms.

Abstract: A plasma source uses radio frequency electromagnetic radiation to ionize and dissociate gas molecules into reactive species within a plasma generation tube and emits the species to react with and remove contaminants from surfaces on a spacecraft. The source of the radiation is an antenna brazed to the outside of the plasma generation tube. Permanent magnets ring the plasma generation tube within a metallic housing to generate a magnetic field. Pole pieces are provided to improve the strength of the field and to improve its uniformity and axial orientation within the plasma generation tube. A plenum and a gas diffusing element distribute gas entering the plasma generation tube.

Abstract: Active electronic circuits are immersed in photonic bandgap crystals (PBC's) that form part of transmission lines for propagation of output signals of the electronic circuits. The output signals of the electronic circuits are accompanied by noise signals that result from spontaneous emission in emission frequency bands which are associated with the active electronic circuits. The PBC's are configured to have photonic bandgaps that include at least a portion of the emission frequency bands. Because the active electronic circuits are immersed in the photonic bandgap crystal, the launch of at least a portion of the noise signals into the transmission line is thereby inhibited. Consequently, the output signal and less than all of the noise signals are propagated along the transmission line, i.e., the noise content of the circuit output is reduced.

Abstract: An earth chord sensor on board a satellite produces an electrical pulse as the satellite spins and sweeps the sensor across the earth. If the satellite is spinning at a low spin rate or if the sensor is measuring a long earth chord, the sensor produces an irregular pulse with sharp voltage peaks rather than a near trapezoidal pulse. The present invention digitizes the output of the earth chord sensor and a processor processes the digitized output through a data buffer to detect the leading edge peak and trailing edge peak of the pulse. The processor may detect the peaks through parabolic curve fitting among the digitized data points of the sensor output. The processor calculates the earth chord time as the time width of the pulse between the detected leading edge peak and trailing edge peak of the pulse and transmits, by telemetry, the calculated earth chord time to a ground station for use in satellite positioning.

Abstract: A circuit and method are presented for making differential voltage measurements when one or both measurement points are at voltages that exceed those allowed by a typical differential amplifier, and is particular useful for monitoring the individual cell voltages of a number of series-connected cells that make up a rechargeable battery in which some cell voltages must be measured in the presence of a high common mode voltage. Each measurement point is connected to an input of a respective voltage divider, with all the divider outputs connected to a multiplexer having two outputs. The two multiplexer outputs are connected to a differential amplifier. When the voltage dividers are "closely matched," the output of the differential amplifier is directly proportional to the differential voltage between the pair of points to which the dividers are connected, and the differential voltage between those two points is accurately determined.

Abstract: A waveguide horn has septums to decrease the side lobes in its E-plane radiation pattern and the input ends of the septums are spaced from the horn's rectangular input port to improve the return loss of the horn. The input ends are preferably spaced from the input port >3a in which a is the dimension of the broad side of the input port.

Abstract: A glass fiber laser system includes a laser resonator cavity having a resonant path and an erbium-doped glass fiber lasing element with an output of from about 1.5 to about 1.6 micrometers within the laser resonator cavity. A light source directed into an input end of the glass fiber lasing element optically pumps the lasing element to emit light. A passive Q-switch lies along the resonant path within the laser resonator cavity. The Q-switch is formed of a host material having a concentration of uranium ions therein, so as to be a saturable absorber of the light emitted by the lasing element. The Q-switch is preferably a uranium-doped fluoride crystal such as U:CaF.sub.2, U:SrF.sub.2, or U:BaF.sub.2.