Abstract: A method for estimating motion of a dual-spin spacecraft having a gimballed momentum wheel. The method disengages the gimbal from its drive train in anticipation of a short disturbance. Then, the gimbal slip resulting from the disturbance is measured. The method may be used to stabilize any dual-spin spacecraft that uses a gimballed momentum wheel. To stabilize the dual-spin spacecraft, the gimbal angle and gimbal rate are measured during and after the disturbance to provide an indication of the inertial spacecraft motion along gimbal axes. The magnitude and direction of the disturbance are determined by comparing motion of the gimbal before and after the disturbance. Then, torques are applied to the gimbal to counteract the spacecraft motion resulting from the disturbance.

Abstract: A charging sensor that uses photoemission to directly measure the electrical potential of a spacecraft in orbit relative to the space environment. The photoemission based charging sensor uses photoemission from a photoemitting conductive plate of a charge probe as a reference point for voltage readings and provides direct measurements of spacecraft charging.

Abstract: An integrated transformer and inductor assembly for use in soft switching or resonant power converters, and the like. The assembly has a planar structure and includes a planar transformer and a parallel inductor. The assembly has a transformer core with a central gap. Planar interleaved primary and secondary winding are separated by insulating layers and are disposed within the transformer core. The parallel inductor is provided by a concentric inductor (reactive) winding disposed adjacent the center of the transformer core, which may be wound around a bobbin. The concentric inductor (reactive) winding carries inductor current, while load current flows mostly in the planar windings. Loss due to magnetizing current is substantially reduced in the present invention.

Abstract: A control method and improved equatorial-normal body-stabilized spacecraft that operates in an inclined orbit. The control method controls pointing of payloads (communication antennas and instruments) and solar arrays disposed on the spacecraft. The method controls the spacecraft to provide Earth-pointing payloads and sun-pointing solar arrays so that the spacecraft body and solar arrays each rotate only around a single axis, a pitch axis of the spacecraft.

Abstract: A method for use on a satellite that automatically inhibits scanning of an Earth sensor to handle sensor intrusions by the sun, moon, or other celestial bodies. In implementing the method, a predicted state vector for the satellite, derived from an orbit propagator, is generated. An attitude profile for the satellite is generated. Then, the satellite state (predicted state vector) and attitude profile are processed to determine Earth, sun, and moon vectors in a satellite body frame of reference at any instant. The Earth, sun, and moon vectors are compared to the Earth sensor field of view and sensor field of view limit boxes to determine if scan inhibiting or Earth sensor switching should occur. The affected Earth sensor is inhibited or switched if an intrusion of the sun and/or moon into the field of view of the Earth sensor is predicted.

Abstract: A method of controlling the orbit of an inclined, eccentric geosynchronous satellite by maintaining its perigee location while simultaneously preventing a reference point on the orbit from moving too far relative to a normal position over the Earth. Doing this changes the semimajor axis of the orbit, which when perturbed away from the geosynchronous value, creates a drift rate relative to the Earth. To correct the argument of perigee and maintain the prescribed tolerance on ground track position, multiple maneuvers must be performed to control the drift rate. The relationship between maximum allowable velocity change and time between maneuvers is defined by the required correction to the argument of perigee and the allowable motion of the reference point.

Abstract: Thermal interface materials for use in space applications. The thermal interface materials comprise a plurality of graphitized thermally conductive (carbon based) fibers 6 that are contained, immersed, or embedded, in one or more substantially non-outgassing polymer matrix materials. Both relatively stiff and relatively stiff and compliant polymer matrix materials may be used to secure the thermally conductive fibers. The thermally conductive fibers and non-outgassing polymer matrix material may be additionally cured to improve their conductive properties. The polymer matrix materials contain volatile condensable material of less than 0.1 percent and exhibit a total mass loss of less than 1.0 percent per an ASTM E595 procedure.

Abstract: An automated spacecraft orbit compensation system and method that maintains a spacecraft in a desired orbit. The spacecraft orbit compensation system and method is automated to minimize human intervention. The system includes apparatus for determining orbital errors (ranging data) and apparatus for determining the duration and orbital location of thruster firings to correct the orbit. Each of the apparatus are located at a ground station. The system and method generates ranging data indicative of the range of the spacecraft. The ranging data are processed to estimate the orbit of the spacecraft. The estimated orbit is used to compute a thruster burn plan for the following N days. The thruster burn plan is uploaded to the spacecraft. The above steps are repeated at regular intervals.

Abstract: A spacecraft having nested reflectors that are released and deployed during a single release event using one or more dual reflector holddowns. The nested reflectors are held in place prior to release by the holddowns and are released during the single release event. The nested reflectors are secured to the body of the spacecraft by hinges attached to respective reflector backup structures and are releasably secured to the body using the one or more dual reflector holddowns. The reflector backup structures are secured by reflector interface brackets of the respective holddowns. An exemplary holddown has a separable tubular housing that is longitudinally secured together between an end cap and a release device. A threaded shaft 28 extends through the tubular housing, the end cap and the release device. A retraction spring is disposed around the exterior of the housing. The reflector interface brackets are secured to the outer and inner housings that attach the plurality of reflectors to the holddown.

Abstract: Rain fade mitigation methods and data broadcast systems that provide improved performance in a rain fade environment. The systems distribute data derived from a transmitting processor by way of a data distribution system to one or more receivers located at remote locations. The transmitting processor may include forward error correction processing software that is used to add forward error correction bits to data packets to be transmitted. When error correction bits are added to the data prior to transmission, the receivers include forward error correction software that processes the received data packets to reconstruct the original data. Data packets with or without error correcting bits may be transmitted two times to the remote locations, which times are separated by a time delay having a duration that is related to a rain fade event, which time delay is sufficient to allow data reconstruction in the presence of the rain fade event.

Abstract: A communication system and antenna system for use on a satellite. The communication system includes a transmitter and/or a receiver that are respectively coupled to the antenna system. The antenna system includes a plurality of stepped slot waveguides that each have a plurality of slots disposed in a broadwall thereof that form an array of slots. Adjacent slots of each waveguide are offset from a centerline of the respective waveguide and are spaced at half guide wavelength intervals, and selected slots are thus located at a different axial positions relative to other slots in the array. A feed waveguide having in input/output port is provided that couples RF energy between the plurality of stepped slot waveguides and the communication system. The stepped waveguide slot array antenna system provides phase control of the beam pattern produced thereby.

Abstract: A ceramic resonator element having high Q, high dielectric constant, and a low temperature coefficient of resonant frequency is enclosed within a cavity to form a composite microwave resonator having reduced dimensions and weight as compared to a simple cavity resonator. In an exemplary embodiment, a pair of tuning screws extend into the cavity along orthogonal axes to tune the structure to resonance along these axes at frequencies near the fundamental resonance of the ceramic element. Several such cavities can be formed in a short length of waveguide by the use of transverse partitions at spaced intervals and coupling between cavities can be accomplished by using simple slot, cross or circular irises. In each cavity, a mode-perturbing screw is positioned along an axis 45° from each of the orthogonal tuning screws, such that resonance along either of the orthogonal axes is coupled to excite resonance also along the other.

Abstract: A thermal harness comprising one or more tows of braided or bundled thermally conductive fiber extending from each of a plurality of heat generating devices to one or more heat dissipating devices. The harness may include an encapsulating membrane to contain the multiple tows. At each end or node of the tows, they are fanned out and splayed onto a patch of nonoutgassing polymer matrix material. A second piece of nonoutgassing polymer matrix material may be used to encapsulate the splayed tows at each node. The nonoutgassing polymer matrix material comprises high conductivity, small diameter fibers thermally coupled to the splayed tows of fiber and to the heat generating and heat dissipating devices. The node may be attached to the heat generating and dissipating devices using an adhesive or pyrolytic graphite flakes disposed between the polymer matrix material and the heat generating and dissipating devices.

Abstract: Improved wavelength division multiplexed optical links and signal processing methods that employ cross tap equalization to reduce crosstalk arising from inadequate optical filtering. After optical filtering and photodetection, the wavelength division multiplexed signals adjacent either side of a signal whose crosstalk is to be reduced are sampled, weighted and are then subtracted from the signal whose crosstalk is to be reduced. This is done using adaptive correlation, performed simultaneously on all signals, each with respect to its respective adjacent channels. The present invention enables more closely spaced optical carriers to be used in the wavelength division multiplexed optical link.

Abstract: Low-cost, miniature, noninvasive power and continuity testing tools for diagnosing and troubleshooting electrical and electronic systems. The tools may be used to diagnose the condition of electrical equipment such as power cords, ignition wires, and ignition systems. Certain tools do not require a power source to operate, while others are battery powered. One tool comprises a liquid crystal display and an antenna connected a LCD element of the display. RF energy radiated by a tested circuit is sensed by the antenna and is coupled to the LCD element which causes the element to emit light. Another tool comprises a battery, a light emitting diode, and a semiconductor integrated circuit switch. The light emitting diode and integrated circuit switch are coupled in series with the battery. The integrated circuit switch is closed when it is in the presence of RF energy, which completes the circuit and turns on the light emitting diode.

Abstract: Nonintrusive tools for testing power and continuity of AC circuits and wiring. Each tool has a conductive probe extending therefrom that is coupled to a positive terminal of power source or is electromagnetically coupled to a coupling wire that is coupled to the power source. A switching/amplifying device is coupled in series with an indicator between terminals of the power source. A contact is coupled to a switching terminal of the switching/amplifying device that is used to operate the tool when touched by a user. An external coupling device having two electrically isolated wires that are twisted around each other to provide electromagnetic coupling therebetween may be employed when the coupling wire is not used. Physical touching of the contact by the user activates the tool. Once the user activates the tool, the probe may used to directly contact “hot” AC terminals or contact a gel placed on unexposed wires to enhance operation of the tool to determine the presence of power or continuity.

Abstract: Improved solar cell circuit layouts and cell structures that protect solar arrays located on spacecraft disposed in geosynchronous earth orbit from electrostatic discharge. An insulating material, such as RTV adhesive, for example, is used as a barrier that disposed in intercell gaps between solar cells. The use of the insulating material modifies sparking in the gaps caused by electrostatic discharge so that, while the spark still occurs, it has different non-destructive characteristics. The use of the insulating material causes no damage to other solar cell materials, such as a Kapton insulating layer or substrate used to support the solar cells. Furthermore, unique solar cell wiring schemes are provided that limit the voltage between adjacent solar cells to 50 volts or less.

Abstract: A Gregorian reflector antenna system optimized for an elliptical antenna aperture. The Gregorian reflector antenna system comprises a main reflector, a subreflector, and a feed horn for illuminating the subreflector. The subreflector illuminates the main reflector with an elliptically shaped feed cone of energy. The subreflector has a surface defined by the equation x 2 a 2 + y 2 b 2 + z 2 c 2 = 1 , where x, y, and z are three axes of the Cartesian coordinate system.

Abstract: A linearized channel amplifier comprising a linear channel amplifier circuit 20 and a nonlinear linearizer circuit located immediately before a high power amplifier. A common control circuit controls the linear channel amplifier circuit and the nonlinear linearizer circuit. The linearized channel amplifier functions as a driver amplifier and improves the linearity and efficiency performance of the high power amplifier across a desired frequency bandwidth. The linearized channel amplifier employs low cost temperature compensation circuits in an interface circuit and a temperature compensation network circuit, and uses a novel methodology to provide for command and control functions that includes a measurement, analytical calculation and setting process. An external personality plug may be to set the performance of the channel amplifier and linearizer.

Abstract: Satellite attitude control methods for use during orbit raising operations to follow a predefined thrust trajectory that meets geometric constraints imposed by sensor and/or telemetry and control antenna fields of view while optimizing the sun angle on the solar array. The method uses low thrust electric propulsion for geosynchronous satellite orbit raising from a transfer orbit to the final geosynchronous orbit. In implementing the methods, a predefined thrust trajectory is generated that is designed to raise a satellite from a transfer orbit to a geosynchronous orbit. A direction-cosines matrix, or quaternion, is generated that aligns a thrust vector defined in the satellite body frame with the predefined thrust trajectory and rotates the satellite body about that vector.