Abstract: A system, apparatus and method provide wireless communications to a geographical area. The system includes at least one atmospheric platform serving as a central relay or node using a star network topology for the geographic area. The atmospheric platform carries a payload that comprises communications equipment. The system further includes a plurality of user equipment units located within the geographic area and at least one ground station or gateway for providing an information pathway between the user equipment units. The gateway has network processing and switching equipment for routing the information between the users. A wireless trunkline carries signals between the gateway and the atmospheric platform. The apparatus and method comprise gateway and payload uplink portions and downlink portions. The downlink portions aggregates and de-aggregates user generated information from the platform to the gateway.

Abstract: A signal transfer device measurement system and method of the present invention measures the signal transfer characteristics of a device under test (DUT) having an analog input port and either an analog output port or a digital output port. The measurement system and method comprise a stimulus waveform generator that produces a stimulus waveform. The stimulus waveform comprises a time sequence of pairs of narrow bandwidth, modulated signals. The stimulus waveform is applied to the input port of the DUT thereby producing an output response signal at the output port of the DUT. For a DUT with an analog output port, the measurement system and method further comprise an analog-to-digital converter (ADC) for digitizing the output response signal and producing digital data and a signal processor for processing the digital data thereby producing measured results.

Abstract: A method of making full-length oligonucleotide arrays provides for the purification of pre-synthesized full-length oligonucleotides from shorter length oligonucleotides and other impurities at the same time the oligonucleotides are deposited on the array. A synthesized mixture that includes desired full-length oligonucleotides and some capped shorter length or "failed" oligonucleotide sequences, is reacted with a linking agent to add a linking group on to the free-end of the full-length oligonucleotides but not the shorter-length oligonucleotides. The resulting mixture is deposited on an array without first separately purifying the mixture to remove the unwanted shorter-length oligonucleotides. After deposition, unbound material, including the shorter length oligonucleotide sequences and other impurities, is removed.

Abstract: In a spacecraft that controls its position and attitude by a plurality of bipropellant thrusters, controlled ejection and vaporization of a single remaining propellant species generates a thrust force to adjust the spacecraft's position and attitude, thereby allowing an extension of the spacecraft's useful life after the other propellant has been exhausted.

Abstract: A nickel-hydrogen energy storage cell includes a hermetic pressure vessel having a wall made of a nickel-base alloy, and a hollow tube made at least in part of palladium and joined to the wall of the pressure vessel such that an interior of the hollow tube is in communication with an interior of the pressure vessel. A heater controllably heats at least a portion of the hollow tube to increase the diffusion rate of hydrogen through the wall of the hollow tube and thereby controllably vent hydrogen from the pressure vessel. The energy storage cell further includes at least one plate set within the wall of the pressure vessel, an electrolyte, and a pair of electrical leads extending from the at least one plate set and through an electrical feedthrough in the wall of the pressure vessel.

Abstract: A mesh material for a spacecraft antenna reflector is disclosed. The mesh material has a base material made from a dielectric fabric. A conductive material, such as nickel, is applied to the dielectric mesh. The type and thickness of the conductive material is adjusted to regulate the final conductivity of the reflective surface to a predefined range. The present invention utilizes a range that reduces PIM while at the same time maintains a high degree of RF reflectivity. The preferred range is 0.01 to 10 ohms per square.

Abstract: A method and system for controlling uplink power for signal transmission in a satellite communication system employing on-board demodulation and remodulation and having a plurality of user terminals that are linked by and that communicate with each other by way of a satellite relay system. A downlink error rate of the data in a downlink data stream is determined based on known data bits. An end-to-end error rate of the uplink data stream and the downlink data stream is determined. An error rate of the signal transmission is then determined based on the downlink error rate and the end-to-end error rate. The signal transmission is then controlled based on the error rate of the signal transmission.

Abstract: A two-terminal voltage or current matched solar cell has up to four photovoltaically active junctions which efficiently convert solar radiation into electricity. The solar cell comprises GaInP, GaAs, and GaInAsP, and in the four junction case, GaInAs is used as well. The invention allows the solar spectrum to be converted into electricity more efficiently than previously.

Abstract: An adhesive is provided for bonding cyanate ester composite parts together which is also plateable with metal once chemically etched. The adhesive comprises a polymeric matrix and a filler of cyanate ester polymer. The polymeric matrix comprises at least one polyepoxide resin and a curing agent, while the cyanate ester polymer filler is present in the adhesive as a powder. In practice, the present adhesive is applied to the surface of cyanate ester composite articles to be bonded and is allowed to cure at room temperature. Thereafter, the surface of the assembly is chemically etched and then plated with metal. The present adhesive enable the complete coverage of the cyanate ester composite assembly with the plated metal, including the adhesive bondlines.

Abstract: An electrical terminal provides an electrical interconnection between the exterior and the interior of the pressure vessel of an energy storage cell. The terminal includes an external electrical conductor exterior to the pressure vessel and an internal electrical conductor within the interior of the pressure vessel. An electrically nonconductive support mounts the electrical conductors to the wall of the pressure vessel. The two electrical conductors are cooperatively engaged, preferably by matching threads. A compliant seal is positioned between the external electrical conductor and the internal electrical conductor, on the one hand, and the wall of the pressure vessel, on the other, and a biasing washer set applies a force between the seal and the electrical conductors to maintain hermeticity in the event that the seal deforms during service.

Abstract: Multiple gain stages are provided in a single traveling wave tube amplifier (TWTA). Each gain stage comprises an interaction circuit, an associated RF input, and an associated RF output. The gain stages are separated by a drift length that is selected to achieve a desired interaction between gain stages. In one embodiment that uses only one TWT, couplers, and adjustment blocks external to the TWT, feed-forward and feedback connections remove intermodulation distortion introduced by the TWTA.

Abstract: Methods for performing attitude maneuvers of a spinning satellite without the use of thrusters, or with a minimal number of thrusters, are disclosed. The attitude maneuvers are primarily achieved through the use of gimballed momentum wheels and solar wing drives. Various maneuvers can be performed depending on whether the satellite has near-zero net momentum or significant net momentum. The maneuvers include sun acquisition, sun hold, Earth acquisition and inversion.

Abstract: A spacecraft with 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 has four thrusters. A control system is provided on the spacecraft which is in electrical contact with the first, second, third and fourth thrusters and which controls the activation and deactivation of the first, second, third and fourth thrusters so that the attitude and orbital velocity of the spacecraft can be controlled only by the first, second, third and fourth thrusters.

Abstract: A paint is a liquid or solid mixture of a plurality of particles and an inorganic binder such as a silicate. The particles have a composition A?xAl(1-x)Ga!.sub.2 O.sub.4 (.delta.In), wherein A is zinc or cadmium, the value of x is from 0 to 1, and the value of .delta. is from 0 to about 0.2. In the liquid mixture, a paint vehicle is also typically present to impart the desired fluidity to the mixture. The solid paint made using this material is white, has very low solar absorptance, and may be made electrically conductive by doping the particles with indium or other appropriate dopant.

Abstract: The invention provides a method for controlling the precession of a spinning spacecraft (20) which allows the spacecraft body to respond to an input torque without the nutation normally attendant when an input torque is applied about one transverse axis to accelerate a spinning spacecraft about that one axis. Dynamic decoupling eliminates nutation through the impression of additional derived feedback torques (44,46) to the input torque control of a spinning spacecraft to oppose or cancel the intrinsic cross-coupling terms (34,36) of the spinning spacecraft's gyrodynamics that give rise to the nutation.

Abstract: There is disclosed a radio frequency device having a housing, a cover disposed atop the housing, and a rod. A fastener such as a nut is attached to the rod and engages the cover. When the fastener is rotated, the cover moves with respect to the housing, thereby changing the volume of the cavity defined by the housing. In this fashion, the device may be tuned to different frequencies. In alternative embodiments, the rod is internally threaded and receives a screw that engages the cover. When the screw is rotated, the volume of the cavity is changed and the device may be tuned.

Abstract: An active microwave notch filter is formed by connecting a photonic bandgap crystal (PBC) in a feedback loop around a microwave amplifier. The PBC has an attenuation bandgap which establishes a frequency range of preferential amplification. Frequency selectivity can be achieved by applying signals to the dielectric members which form the PBC to vary their dielectric constants, and thus the bandgap, or by selecting among multiple parallel PBCs. Antennas are provided to transduce the electrical input to the PBC into electromagnetic radiation, and then back to an electrical signal after the radiation has been filtered by the PBC.

Abstract: A spacecraft traveling in a volume of space receiving radiation from the sun and encountering an undesired force. The spacecraft has a solar panel movably attached to said spacecraft. The spacecraft further includes a solar panel controller which controls the movement of the solar panel, wherein the controller moves the solar panel in a time modulated manner so that a torque is generated which compensates for the undesired force.

Abstract: A method of repairing an area of metallization that has lifted from a circuit board substrate uses a dry film epoxy placed between the lifted metallization and the substrate. Downward pressure and heat are simultaneously applied to the lifted area to rebond it to the substrate. Both metallization pads and traces may be repaired with the method, and the resulting bond may be stronger than that originally present. When heated, the dry film epoxy will melt and cure very quickly, requiring no further processing. The method is particularly useful when repairing circuit boards intended for microwave circuitry, in which conductive ribbons are gap welded to metallization pads. A metallization pad repair operation may be combined with a ribbon attachment operation, accomplishing both with one gap welding operation. The gap welder provides the downward force and heat necessary to bond the ribbon and repair the lifted pad.

Abstract: A method and sensor for accurately measuring DC current includes an electromagnetic circuit component, such as a current transformer, having a saturated state and an unsaturated state which generates a DC current based on the DC current being measured. The current transformer includes a first circuit for generating the DC current being measured. A second circuit is electromagnetically coupled to the first circuit to generate a constant DC offset current so as to minimize error at low levels of the measured DC current. A third circuit is electromagnetically coupled to the first circuit for generating a third DC current representative of the first DC current. The first DC current is then measured based on the third DC current. The measured first DC current is then adjusted based on the added second DC current. A sampling circuit is operatively coupled to the third circuit component for sampling the third DC current during a sampling interval.