Abstract: An electronic embedded command module to control devices located in spacecraft includes a serial command decoder to decode serial digital input commands and control a switch matrix, a command buffer to provide a compatible serial digital input command to the serial command decoder, a standby circuit to control power to the serial command decoder, and a switch matrix to provide output commands. A method for controlling devices located in a spacecraft in response to a serial digital command signal. The method includes receiving the serial digital command signal, changing from an inactive state to an active state, processing the command signal while maintaining the active state, generating an output signal, and returning to the inactive state. This electronic command module controls its own power status and consumes negligible current when in the inactive state. This electronic command module reduces wire harness and command module weight and lowers system design, wire harness and command module cost.

Abstract: A 3D microwave switch having a plurality of waveguide transmission lines configured in a polyhedron and with I/O microwave ports at the corners. An actuator selectively moves respective reeds in the waveguide transmission lines between a signal-attenuating position abutting the interior surface of the waveguide transmission line and a signal-conducting position substantially coaxial with the waveguide transmission line and abutting the signal lines of the I/O microwave ports coupled to opposite ends of the waveguide transmission line. Preferably, the transmission lines and ports are formed in a tetrahedral-shaped conductive cavity with a single 4-pole magnet at its center for actuating the reeds or in an octahedral-shape with different actuators for each reed.

Abstract: A system for simultaneously measuring strains in a test member includes spatial-position members which are coupled to different portions of the test member and first and second displacement sensors which are spaced apart by a sensor space and coupled to the spatial-position members. Linear and bending deformations of the test member are calculated as functions of the responses of the displacement sensors and of the sensor space.

Abstract: A digital spacecraft antenna tracking system and method are provided which utilize an array of antenna feed elements oriented relative to a shaped spacecraft reflector antenna system each of which generates an output signal corresponding to a received incident signal. The outputs can be processed by a mixer/multiplexer (M/MUX) before processing by a digital tracking control receiver. The direction of a beacon signal incident on the spacecraft reflector antenna system is obtained by the TCR by comparing the beacon response of the M/MUX to a set of premeasured responses to incident signals having a known direction or orientation relative to a reference tracking grid. The premeasured responses are stored in a memory as a set of reference responses. Once the direction of the signal is obtained, the TCR assigns control voltages which are used by the spacecraft to steer the spacecraft antenna to a desired pointing direction relative to the beacon signal.

Abstract: Transponder systems are disclosed for routing signals from a plurality of input frequency channels at each of a plurality of receive antennas to a plurality of output frequency channels at each of a plurality of transmit antennas. The routing is preferably processed at an intermediate frequency. A plurality of bandpass filters are coupled to each receive antenna to define input signal paths. First and second mixers are positioned in series with each bandpass filter. A mixing signal at the first mixer adjusts the frequency of a selected one of the input signals to pass it through the bandpass filter and onto the respective input signal path. A mixing signal on the second mixer translates the frequency of that input signal to have a frequency order in the intermediate frequency band that corresponds with the frequency order of a selected one of the output frequency channels at its respective transmit antenna. Each of the transmit antennas is coupled to a common signal path of an adder.

Abstract: A structure protected by a sunshield film includes an article, for example a spacecraft radio-frequency antenna, and a sunshield film protecting the article surface. The sunshield film is formed as a sheet substrate made of a material that is transparent to radio frequency energy, a white coating on one side of the sheet substrate, and a black coating on the other side of the sheet substrate. The white coating and the black coating each have a surface resistivity of from about 10.sup.8 to about 10.sup.9 ohms per square.

Abstract: A mechanically pumped heat pipe having an evaporator section and a condenser section disposed at a location below the evaporator section. A solenoid actuated cavitation-free mechanical pump returns a working fluid from the condenser section to the evaporator section. An armature connected to the piston head of the mechanical pump is disposed inside the condenser section and the solenoid coil is disposed outside of the condenser section in the vicinity of the armature permits the piston head to be periodically reciprocated without any electrical or mechanical feedthroughs.

Abstract: In order to control the deployment of secondary deployment structures in a deployment system that includes both a primary and a secondary deployment, an improved deployment sequencer utilizes the rotational motion of primary deployment structures. In particular, the rotational motion serves to control the retention and release of the secondary deployment structures during the primary deployment. Still more specifically, the deployment sequencer restrains the deployment of the secondary deployment structures until the primary deployment structures have deployed or rotated far enough so that collisions between the secondary deployment structures are avoided.

Abstract: A circuit for canceling cross polarization interference has a first signal input and a second signal input. An adjustable cancellation network circuit is coupled to the first input and the second input. The adjustable cancellation network circuit has a first programmable vector modulator having a first weight and a second programmable vector modulator having a second weight. The first weight is correlated to the first input signal to obtain a first output signal. The second weight is correlated with the second input signal to obtain a second output signal. A performance measurement circuit is coupled to the cancellation network circuit and receives the first output signal and the second output signal. The performance measurement circuit generates a first correlated signal corresponding to the amount of interference in the first correlated signal and a second correlated signal corresponding to the amount of interference in the second correlation signal.

Abstract: A fully regulated multiple source power bus subsystem for a satellite having at least a solar panel array and a battery providing unregulated sources of electrical power. The battery and solar panel array are connected to one or more multiple source bus regulators to produce a fully regulated bus output at one or more preselected voltages. Each multiple source bus regulator automatically switches between the battery and solar panel array and may produce either a positive or a negative bus voltage. A battery charge controller controls the charging of the battery when the output voltage of the solar panel array is greater than the output voltage of the battery.

Abstract: A limiter for a solid state power amplifier (SSPA) protects the amplifier against large peak, short duration noise signals while controlling drive level related phase shifts. The limiter limits noise signals to a safe input level for the power output section of the SSPA. It also uses a pair of resistor networks at its input and output to dampen reflected energy and thus control drive level related phase shifts.

Abstract: There is disclosed an angle positioning platform for positioning objects around first and second axes and a gearbox for same. The platform comprises a base, an intermediate stage, and an upper stage. The platform may have motors and first and second output gearboxes connected to the motors for driving the platform. The orientation of the stages of the platform permits the platform to be relatively compact in a stowed position and to have high angular rotation from the stowed position to a maximum travel position. The gearboxes may have a mechanism for isolating worm shafts and wormgears from heavy loads when the platform is in the stowed position. Another aspect of the invention is an output gearbox with a wormgear having stops for stopping rotation of a matingly engaged worm. Another aspect of the invention is a gearbox having torsion springs to counter backlash in the gearbox.

Abstract: A spacecraft has internal structure which generates heat, and a radiator element in thermal communication with the spacecraft internal structure. The radiator element has a radiating surface and a coating on the radiating surface including a white thermal control paint. The paint has an initial solar absorptance of not greater than about 0.20 and an initial infrared emittance of not less than about 0.80. The standard end-of-life projected solar absorptance is not more than about 0.3 for a paint with an inorganic binder, and the standard end-of-life projected solar absorptance is not more than about 0.6 for a paint with an organic binder.

Abstract: A method for simultaneously controlling satellite nutation, sun angle and attitude walk using a dual-slit sun sensor and thrusters. The sun angle and nutation angles are computed from sun sensor data, and the thrusters are fired when their use improves both sun angle and nutation. Precession around the sun line is controlled by constraining firing, in the simplest case, firing only when the angular momentum is precessed directly toward or away from the sun. Precession maneuvers are implemented by commanding a new sun angle and precession plane spin phase.

Abstract: A BJT, an inductor, and an RTD are configured to define a negative resistance oscillator circuit that is suitable for monolithic integration. The BJT is forward biased so that the RTD operates at a DC operating point (I.sub.Q,V.sub.Q) on its characteristic I-V curve in its negative differential resistance region. The thermal noise inherent in the circuit causes it to start oscillating about the DC operating point (I.sub.Q,V.sub.Q) where the RTD's negative resistance R.sub.n provides positive feedback that amplifies the oscillations until equilibrium is established thereby producing a sinusoidal waveform. The low power BJT/RTD oscillator operates at power levels approximately one-tenth those of known integrated feedback oscillators and oscillates at frequencies in the hundreds of Ghz range that are currently only achievable using waveguide oscillators.

Abstract: Microwave power divider/combiners are provided which divide received powers at each of 2.sup.n input ports transmit the divided powers to each of 2.sup.n output ports and combine the transmitted powers at each of the output ports. They have through transmission lines which each couple respective pairs of the input and output ports. In addition, they include shunt transmission lines, an input network of transmission lines which couples the input ports to first ends of the shunt transmission lines and an output network of transmission lines which couples second ends of the shunt transmission lines to the output ports to thereby provide transmission paths from each of the input ports to each of the output ports. The input and output transmission-line networks are configured to be identical and to cause the power divider/combiner to have interport symmetry between the input and output ports and intraport symmetry between any equal sets of input and output ports.

Abstract: An attenuation ring assembly for mounting between the payload section and the booster section of a launch vehicle is disclosed. The ring assembly acts as a transient filter to delete or minimize harmful shock and vibration frequencies which might otherwise reach and possibly damage delicate electronic components and the like in the launch vehicle payload.

Abstract: An article such as a spacecraft thermal radiator includes a substrate having a white thermal control coating thereon. The thermal control coating is formed of a matrix of a silica/silicate transformation product of a ceramic precursor, and a plurality of doped zinc oxide pigment particles distributed in the matrix. The zinc oxide pigment particles are doped with an element that forms shallow donorlike states in the zinc oxide. The coating has a solar absorptance of from about 0.2 to about 0.3 and an initial electrical resistivity of from about 1.times.10.sup.6 ohms per square to about 1.times.10.sup.8 ohms per square. The coating is stable at continuous operating temperatures of 225.degree. C., with short-term exposures of up to 800.degree. C.

Abstract: A positioner includes an output platform and a two axis bearing-suspension which permits the output platform to rotate about two orthogonal axes. The output platform is positioned by a pair of actuators which are mounted, as is the bearing suspension, to a positioner base. The actuators include bevel gears which engage ratchets to couple the actuators and the platform.

Abstract: A method of making a lightweight, microwave electronic structure includes the steps of forming a rigid, glass structure having a desired density by a sol-gel process and thereafter uniformly coating the formed glass structure with an adherent and uniform conductor. The sol-gel process may be carried out by polymerizing a mixture comprising silicon alkoxide, water and an alcohol. The coating process may be carried out by coating the glass structure with a solution comprising an organic compound of a metal dissolved in an organic solvent and thereafter volatizing the organic solvent.