Abstract: In a satellite transponder architecture employing digital signal processing, a power monitor samples the data stream of carrier frequency samples on board the transponder and computes a power level for each of the carriers. This provides accurate and high frequency resolution power measurements within the communications link. These measurements are useful for computing critical transponder characteristics such as the effective isotropic radiated power (EIRP), receiver sensitivity, uplink sensitivity, operating points and, in a system using a phased array antenna, the total and component powers for each beam. The power monitor eliminates problems associated with external measurement methods, and improves the overall accuracy and reliability.

Abstract: A method of loading propellant into a spacecraft that comprises storing and transferring propellant in a portable propellant loading tank, temperature conditioning and helium saturating the propellant in the propellant loading tank, transferring the loading tank to a launch site, coupling the loading tank to the propellant storage tank, and pressurizing the portable propellant loading tank to transfer the propellant to the propellant storage tank in the spacecraft. The method may further comprise weighing the propellant loading tank during propellant transfer, venting the propellant storage tank in the spacecraft to a receiver tank, and weighing the receiver tank during propellant transfer. The amount of propellant transferred to the propellant storage tank is equal to the difference between the measured weights of the respective loading and storage tanks.

Abstract: A method for residual coding of model failure regions in compressed video sequences in which a database of residuals for previous model failures is maintained at both the encoder and the decoder. The residuals for each determined model failure regions are compared with the residuals for previous model failures for the same region. In the event a current residual is identified in the database, only the index to the residual in the database needs to be sent. An additional residual taken after the model failure region has been partially corrected with a current residual identified in the database may also be transmitted. This mode provides increased quality at reduced bit rates by maximizing the utilization of previously transmitted or stored data. The process continuously updates the database at both the encoder and decoder when the current residual is not found. The process uses residuals of residuals to provide increased quality of reduced bit rates.

Abstract: Frequency multiplexers that incorporate either a power divider network or a power coupling cavity in conjunction with photonic bandgap filters. The frequency multiplexers comprise a signal input and a plurality of signal outputs. In a first embodiment of the multiplexer, a 1-to-N power divider network is coupled to the signal input, and a predetermined number of photonic bandgap filters are coupled between the divider network and the plurality of signal outputs and that are driven by the divider network. Each photonic bandgap filter has an predetermined bandpass characteristic such that the plurality of filters cover the total input signal bandwidth. In a second embodiment of the multiplexer, a cavity is formed between the signal input and the plurality of filters. The spatial locations of the filters tailor the propagation properties of the cavity so that a corresponding plurality of propagating modes are established linking the different input frequency bands and the signal output.

Abstract: A closed-loop heat pipe transport design for a deployment application having a flexible section which connects to a payload structure and a deployable structure. The flexible section folds over itself while the deployable structure is stowed. Upon rotation of the deployable structure around a predetermined axis, the flexible section unfolds, with a portion of the flexible section passing through the predetermined axis. When the deployable structure has completed its rotation and is fully deployed, the components of the flexible section will lie in substantially the same plane.

Abstract: A method and system of orienting a payload of an orbiting spacecraft (14) to maintain a desired pointing profile in the presence of orbit inclination. A cone (12) is determined which is traced in inertial space by a pitch axis of the payload to maintain the desired pointing profile throughout an orbit. A bias momentum vector of the spacecraft (14) is oriented at an attitude which lies along the cone (12). The attitude has a nonzero angle with respect to a plane spanned by an orbit normal vector and an equatorial normal vector. The payload is rotated about a single body-fixed axis perpendicular to the pitch axis to align the pitch axis along the cone (12). As a result, the desired pointing profile is maintained throughout the inclined orbit.

Abstract: The present invention relates to an apparatus for transferring heat in a spacecraft. The apparatus includes a flexible heat pipe having a first section, a second section, and a flexible section. A first member of a spacecraft is coupled to the first section of the flexible heat pipe, and a second member of the spacecraft is coupled to the second section of the flexible heat pipe. The first member of the spacecraft is in a rigidly fixed relationship to the second member of the spacecraft. A method of using a heat transport system for transferring heat in a spacecraft is also provided. The method includes providing a flexible heat pipe having a first section, a second section, and a flexible section, coupling the first section of the flexible heat pipe to a first member of a spacecraft, and coupling the second section of the flexible heat pipe to a second member of the spacecraft rigidly fixed with respect to the first member.

Abstract: A method for estimating high frequency components of a compressed image normally lost during a data compression stage and an encoder and a decoder for carrying out same. The image is compressed to obtain unquantized and quantized frequency domain coefficients. An inverse quantization is performed on the quantized coefficients to obtain lossy frequency domain coefficients. Loss characteristics of the high frequency components are then determined based on the unquantized frequency domain coefficients and the lossy frequency domain coefficients according to one of several methods. Finally, the loss characteristics are coded to obtain encoded loss data corresponding to the lost high frequency components.

Abstract: A spacecraft having a spacecraft body and a heat radiator attached to the spacecraft body. The heat radiator is in thermal contact with the spacecraft body and the heat radiator moves from an initial position to a deployed position where heat is emitted therefrom. The predetermined deployed position is located at an angular position .theta. as measured relative to the initial position, wherein .theta. ranges from approximately 135.degree. to less than 180.degree..

Abstract: An improved broad band "Y" junction isolator/circulator at V-Band is disclosed. A "star"-shaped ferrite structure is positioned in the isolator housing. The ferrite structure comprises two triangular-shaped ferrite members positioned 180.degree. from each other and bonded together.

Abstract: A method is provided for removing metal oxide debris from various types of surfaces, both metallic and nonmetallic. Specifically, the surface to be cleaned is treated (preferably by immersion) with a preheated solution of 65 to 71 wt % (55.3 to 62.0 vol %) nitric acid, which is roughly equivalent to reagent grade nitric acid. The temperature of the solution is within the range of about 160.degree. to 175.degree. F. (71.degree. to 79.degree. C.). The preheated solution dissolves any metal oxide debris present on the surface, which may then be rinsed away following treatment. The method effects the removal of metal oxide residue from surfaces without further degrading the surfaces being cleaned. Further, the method is capable of cleaning internal surfaces of components without requiring disassembly of sealed or welded components, since all that is needed to effect cleaning is contact between the surface to be cleaned and the preheated solution.

Abstract: A monolithically integrated solar cell microarray includes an isolation layer or multiple isolation layers between a substrate and a solar cell layer, and a trench in the solar cell layer that exposes the isolation layer. Together the isolation layer and trench define solar cells that are spaced apart and electrically isolated on the monolithic substrate. The solar cells are scaled to provide a desired current. Base contacts and integral emitter contact/interconnects connect a number of the scaled solar cells in series to sum their voltages to supply a desired output voltage and current. The trench and integral emitter contact/interconnects are formed using photolithographic etching and liftoff processes, respectively, which are much quicker and less expensive than the conventional dicing and soldering processes.

Abstract: An apparatus and method for translating a spacecraft (102, 108) from an injection orbit (114) about a central body (100) to synchronous orbit (122) in a time efficient manner. The spacecraft (102, 108) includes propulsion thrusters (50) which are fired in predetermined timing sequences controlled by a controller (64) in relation to the apogee (118) and perigee (120) of the injection orbit (114) and successive transfer orbits (114). During transfer orbit, the spacecraft's inertial attitude is adjusted to track sun movement. The spacecraft is injected into a particular injection orbit that offsets moments created by tracking sun movement to maintain stable transfer orbits.

Abstract: An energy storage cell includes a cylindrical pressure vessel, a porous ceramic coating on the interior surface of the pressure vessel, a plurality of insulating stripes of an electrically insulating polymeric coating on the interior surface of the porous ceramic coating, and a plurality of catalytic stripes of a catalytic material overlying the plurality of insulating stripes. The insulating material is preferably a polymer such as polytetrafluoroethylene. The catalytic material catalyzes the chemical combination of hydrogen and oxygen, and is preferably a mixture of platinum powder, polytetrafluoroethylene, and methocel. The insulating stripes and catalytic stripes lie around the circumference of the cylindrical pressure vessel and extend parallel to the cylindrical axis of the cylindrical pressure vessel. The energy storage cell further includes a plate stack having a plurality of plate sets within the wall of the pressure vessel, with the plate sets lying perpendicular to the cylindrical axis.

Abstract: A method and system of attitude steering and momentum management for a spacecraft suitable over a wide range of orbit altitude and inclination parameters and a similar wide range of mission steering profiles is provided. The system utilizes two active momentum wheels positioned with their spin axes nominally coaligned on the spacecraft pitch axis. Each wheel is pivoted by jackscrew type mechanisms which allow the angular momentum to be tilted (e.g. within the range 0-45.degree. from the nominal alignment with respect to the spacecraft body). The spacecraft control processor generates wheel torque commands for the wheel speed electronics and jackscrew drive commands for the platform assemblies in order to adjust the speed and amount of tilt of the momentum wheels. The invention provides a two-momentum wheel array that allows use of either momentum bias steering or large angle zero-momentum steering and accommodates multiple orbit geometries and varying degrees of attitude steering agility.

Abstract: A full shunting BVL with current sense capability includes a pair of parallel connected switches that switch with the same duty cycle D/2 but 180 degrees out of phase to provide current from a power source through a coupled power inductor to a bus. A current transformer is provided with first and second windings connected in series with the pair of switches, respectively, and a third winding. The alternating conduction of current through the first and second windings produces a bidirectional voltage across the third sensor winding that automatically resets the current transformer's ferrite core during each cycle. As a result, the bidirectional voltage can be rectified to produce a current sense signal. The current sense signal is used to provide current-mode control to regulate the bus voltage and supply the demanded load current. The current sense signal can also be used to provide current limiting and current sharing, which allows multiple BVLs to be connected to the same solar array.

Abstract: A packaged electronic structure includes an electronic device, and a package to which the electronic device is affixed. At least a portion of the package is made of a composite material of aluminum nitride dispersed in aluminum. The composite material is preferably prepared by mixing powders of the aluminum nitride and aluminum, and thereafter pressing and sintering the mixture.

Abstract: A method of and system for applying single gimbal control moment gyros to spacecraft attitude control employing two control moment gyros with nominal spin axes anti-parallel and gimbal axes displaced at a fixed angle in the plane normal to the nominal spin axes to achieve two orthogonal body fixed control torques using two wheels. If the gimbal axis displacement of each of three wheels is 120 degrees, two wheels provide independent uncoupled orthogonal two-axis control, and the third can substitute, in the event of failure, for either of the two requiring no change in control law or performance.

Abstract: A pair of dual-gridded shaped reflectors (10) and (20) are arranged one behind the other for transmitting and receiving orthogonally polarized energy waves. A front reflector (10) has a first shaped reflective surface (12) formed on a first body surface (14) for providing a first shaped beam coverage. A rear reflector (20) has a second reflective surface (22) formed on a second body surface (24) for providing a second shaped beam coverage. The first and second reflective surfaces (12) and (22) have substantially identical surface contours and include reflective grids (13) and (23). The reflective grids (13) and (23) are orthogonal with respect to each other so as to handle orthogonally polarized energy. The first and second shaped reflective surfaces (12) and (22) are arranged offset and tandem from each other so as to provide first and second focal points (16) and (26) separate from each other while providing substantially identical first and second shaped beam coverages (15) and (25).

Abstract: Methods and systems for stabilizing satellite spin about an intermediate inertia axis (Z) are disclosed. A set of gyros (22) sense the X component and the Y component of the angular velocity of the satellite body. A single degree of freedom momentum wheel (26) has a fixed transverse orientation with respect to the intermediate axis in order to store momentum. In one embodiment, the momentum wheel (26) is oriented to store momentum parallel to the Y axis. A tachometer (30) senses the rotation rate of the momentum wheel (26). A processor (24) forms a control signal representative of a control torque to be applied to the momentum wheel (26). The control torque is based upon the X component and the Y component of angular velocity of the satellite, and the angular velocity of the momentum wheel (26).