Abstract: A method of front end preparation for efficient coupling of light into a fiber while preventing fiber damage from an incident beam, includes the steps of stripping an end of an outer cladding of the fiber. The step of stripping produces a stripped end of the fiber. The stripped end is then coated with a polymer to produce a polymer coating such that a length of a core of a multi-mode fiber (or an inner cladding of a single-mode double cladding fiber) is bare beyond the polymer coating. Thereby, an extended end of the core or inner cladding is left. For a portion of an incident beam that misses the core or inner cladding, such portion is allowed to diffract from the extended end, while leaving the fiber undamaged.

Abstract: A method is provided for using at least two lunar flyby maneuvers to transfer a satellite from a quasi-geosynchronous transfer orbit having a high inclination to a final geosynchronous orbit having a low inclination. The invention may be used to take the inclination of a final geosynchronous orbit of a satellite to zero, through the use of a first leading-edge lunar flyby and subsequent successive leading or trailing edge lunar flybys resulting in a geostationary orbit.

Abstract: The present invention is directed to improved coupling mechanisms for TE.sub.011 and TE.sub.01.delta. mode resonators. In one embodiment, the coupling mechanism provides an adjustable connection for transferring electromagnetic energy from a first resonator to a second resonator. Once the resonators are coupled, the coupling mechanism is adapted to allow adjustment of the magnitude and/or the phase of the electromagnetic energy while preserving the electromagnetic connection between the resonators. In another embodiment, the coupling mechanism provides a connection of the resonators using a waveguide. By varying the connection of the resonators with respect to the waveguide, positive relative coupling and/or negative relative coupling of the electromagnetic energy transferred between the waveguide and the resonators is provided.

Abstract: An improved solar cell interconnect comprises a first connecting portion for connection to a first solar cell and a second connecting portion for connection to a second solar cell immediately adjacent the first solar cell. A stress portion is disposed between the first and second connecting portions such that the stress portion can be positioned between the first and second solar cells. The stress portion has a plurality of alternating loop portions that form an undulating pattern.

Abstract: An improved photovoltaic cell, according to one embodiment, includes a base layer; a primary window layer having a first type of doping, with the primary window layer being disposed over the base layer; and a secondary window layer having the first type of doping, with the secondary window layer being disposed over the primary window layer. In another embodiment, the improved photovoltaic cell has a multilayer back-surface field structure; a base layer disposed over the back-surface field structure; and a primary window layer disposed over the base layer. In yet another embodiment, the photovoltaic cell includes a base layer; and a primary window layer disposed over the base layer, with the primary window layer having a thickness of at least about 1000 Angstroms.

Abstract: An optical display employs a liquid crystal cell with a d.DELTA.n/.lambda. of approximately 0.2-0.8, allowing the cell's optical transmissivity to be modulated by an applied electric field through a dominant non-polarization rotation effect. For visible wavelengths, d.DELTA.n is approximately 0.1-0.4 microns, with a preferred value of about 0.25 microns. Applications include a reflective projection display in which input light is polarized at a greater than 0.degree. and less than 90.degree. angle, preferably about 20.degree., to the input LC directors of a twisted nematic cell; a reflective direct view system in which a quarter-wave plate is substituted for a polarization analyzer; and both a reflective and a transmissive guest-host system in which optical absorption by dye molecules is the dominant modulation mechanism.

Abstract: A unique feed structure for improving the cross-polarization performance of a reflector antenna system is disclosed. According to the present invention, the feed structure is an array including a number of feeds, which are rotated in a predetermined fashion to yield superior cross polarization performance of the antenna system. The array feed in the center of the feed structure is positioned approximately in the focus of the antenna reflector. The array feeds located on the y-axis are slightly rotated in either a clockwise or a counter-clockwise manner. The magnitude of the rotation is proportional to the distance of the feeds from the x-axis along the y-axis. The rotation of the feeds yields significant performance in cross polarization performance, while having little or no co-polarization effect.

Abstract: An attitude sensing system utilizing simplified techniques and apparatus includes a spacecraft control processor which receives signals from an inertial measurement unit and two attitude sensors. The spacecraft control processor calculates a time-varying gain matrix for estimating attitude errors and gyroscope drifts corresponding to the axes of the inertial measurement unit. In special cases where the separation angle between the attitude sensor vectors is less than approximately 10 degrees, the time-varying gain matrix is computed as a fixed gain matrix and a corresponding desensitizing factor.

Abstract: A system and method for determining the location of a source of interference for a communications satellite. The system has an antenna array located on the earth facing panel of the communications satellite. The method and system determine the direction of a source of interference relative to the satellite's own coordinate system. The angle of arrival of the interference signal is determined with respect to the horizontal and vertical baselines of the coordinate system and by comparing the outputs of the appropriate antennas in the antenna array.

Abstract: In a SIMD architecture having a two dimensional array of processing elements, where a controller broadcasts instructions to all processing elements in the array, a dynamically reconfigurable switching means useful to connect four of the processing elements in the array into a group in accordance with either the broadcast instruction of the controller or a special communication instruction held in one processing element of the group, the switch includes at least one dataline connected to each processing element in the group. A multiplexer is connected to each data line and to the controller and to a configuration register. It is adapted to load the special communication instruction from the one processing element in the group into a configuration register and to operate in accord with either the broadcast instruction from the controller or the contents of the configuration register to select one of the four data lines as a source of data and applying the data therefrom to a source output port.

Abstract: A rocket engine is prepared by fabricating a combustion chamber having an annular wall as a single piece of material. The wall has a first axial region with a first inner diameter, a second axial region with a second inner diameter greater than the first inner diameter, and an inner wall step transition between the first axial region and the second axial region. The combustion chamber is attached to an injector by bonding an annular metallic deposit to the first axial region of the combustion chamber, providing an annular adaptor ring, first welding the adaptor ring to the metallic deposit, and second welding the adaptor ring to the injector.

Abstract: Autonomous slewing of a spacecraft about a desired axis using reaction wheels permits a maximum slew rate without wheel saturation even with one wheel failure. The slew is carried out if the total angular momentum of the spacecraft is less than a momentum storage threshold determined from reaction wheel availability. The momentum threshold may be found as the radius of a sphere inscribed in a polyhedron in momentum space, the polyhedron based on the maximum single wheel capacity and the geometry of the reaction wheel system as well as the reaction wheel availability. The momentum available for the slew is determined from the total angular momentum and the availability of each reaction wheel. The slew rate magnitude and slew direction are based on the available momentum.

Abstract: A method for controlling orbiting spacecraft uploads a plurality of parameters to an onboard processor, the parameters including a plurality of quaternion elements describing an inertial to orbit reference frame, and including radial position, radial velocity and angular rate of the spacecraft. Parameters are input for processing one of a plurality of propagation algorithms, preferably calculating said propagation algorithms with the uploaded parameters, computing enhanced time of day vectors, and computing ground time of day angles from the enhanced time of day vectors for adjusting the payload pointing angle, such as an antenna pointing angle, of the satellite. Preferably, the calculating step comprises integrating an orbital state vector with a second order Runge-Kutta integration algorithm. In addition, enhanced time of day fault processing provides an internal check on integration accuracy and is checked every time of day update.

Abstract: A Yb-doped fiber laser uses a homogeneously-broadened material. The disclosed laser design is particularly advantageous for operating the fiber laser between 970-980 nm and using this output as a pump for an Er-doped fiber amplifier (EDFA) having an absorption band between 970-990 nm. Using a homogeneously-broadened host glass, for example alumino-germano-silicate or fluoride glass, significantly reduces the inefficiency that can result from the three-level nature of Yb-doped fiber laser transitions that are required for operating it at approximately 976 nm.

Abstract: A spacecraft attitude control system includes a Momentum Wheel Assembly (MWA) or a Reaction Wheel Assembly (RWA), containing a spinning flywheel, mounted by the use of a mounting bracket to a rotary gimbal which is mounted to spacecraft. The operating MWA/RWA unit is rotated by the rotary gimbal about the gimbal's axis of rotation generating a torque which is provide to the spacecraft, resulting in its movement. The system has the added advantage that the majority of the components are commercially available off-the-shelf products.

Abstract: A launch lock mechanism having a clamp assembly that secures multiple independent brackets. The brackets are attached to components to be deployed from a satellite. A pyrotechnic separation device actuates the clamp assembly. Both the pyrotechnic device and the clamp assembly remain independent of the brackets and components after deployment.

Abstract: Methods are provided for accurate insertion of a constellation of satellites into a common orbit plane with a mean inclination .theta.. In an embodiment of the invention, an initial satellite is inserted on an initial insertion date and, for each of subsequent satellites, a respective orbit insertion date is selected. With reference to the latter date, the initial insertion RAAN is updated to find a current RAAN. This updating is accomplished with knowledge of a regression rate of the initial satellite's orbit normal about a Q vector. With reference to the Q vector's inertial position, an instantaneous inclination that corresponds to the mean inclination .theta. and the updated RAAN is then derived. Finally, the subsequent satellite is injected into an orbit having the instantaneous inclination and the current RAAN.

Abstract: An improved optical rotary joint is achieved by transmitting information in the form of an optical signal from a part of the de-spun portion outside the rotational axis to the spun portion, or vice versa, thereby creating a continuous communication path 360.degree. about the rotational axis. The optical rotary joint includes either a plurality of transmitters on one portion and a detector on the other portion, or a transmitter on one portion and a plurality of detectors on the other portion. In the former, the transmitters are controlled such that only the transmitters transmitting optical signals that will be detected by the detector at a given point in the rotation are activated and the remaining transmitters are deactivated. In the latter, the detectors are controlled such that only the detectors detecting the optical signal transmitter by the transmitter at a given point in the rotation are activated and the remaining detectors are deactivated.

Abstract: An article is a liquid or solid mixture of a plurality of particles and a binder. The article may be a paint or a freestanding film. The particles have a composition A[xAl(1-x)Ga].sub.2 O.sub.4+.gamma. (.delta.In), wherein A is zinc, magnesium, and/or cadmium, the value of x is from 0 to 1, the value of .delta. is from 0 to about 0.2, and the value of .gamma. is less than about 0.2. In the liquid paint mixture, a paint vehicle is also typically present to impart the desired fluidity to the mixture. The solid paint or film 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: Flexible, lightweight reflective sheets are positioned to concentrate solar radiation upon spacecraft solar panels. The sheets are positioned with inner and outer spring members which urge each sheet towards a planar configuration and further urge the sheet in a rotation away from a solar panel face. Restraint members in the form of tethers limit this rotation to place the sheet in a deployed position in which it defines an angle with the panel to reflect solar radiation onto the panel face. The increased incident radiation permits a reduction of the number of solar cells with consequent savings in spacecraft cost and weight. The spring members are configured to permit rotation to a stowed position behind the solar panel. In this position, the tethers are received into guides which are configured to initiate automatic deployment of the spring members and their reflective sheets.