October 2001

Briefs : Software
Software for Automated Ortho-Rectification of SAR Images

The Automated SAR Ortho-rectification Software System enables users of synthetic-aperture-radar (SAR) data to form processed images that are free of the distortion caused by the SAR imaging geometry and topography. The software consists of four modules:

Briefs : Mechanical & Fluid Systems
Actuated Ball-and-Socket Joints

The term "actuated ball-and-socket" (ABS) characterizes a proposed class of ball-and-socket joints that would incorporate ultrasonic motors and other piezoelectric actuators to generate multidimensional actuation. In some applications, ABS joints could supplant traditional joint-and-actuator assemblies that...

Briefs : Materials
End Caps Increase Thermo-Oxidative Stability of Polyimides

Latently reactive end caps have been investigated as improved means to increase the thermo-oxidative stability of polyimides of the polymerization of monomeric reactants (PMR) type, which are often used as the matrix resins of high-temperature-resistant composite materials. The present...

Briefs : Materials
End Caps for More Thermo-Oxidative Stability in Polyimides

An additional class of end-cap compounds that increase the thermo-oxidative stability of polyimides of the polymerization of monomeric reactants (PMR) type has been invented. The prior class of end-cap compounds in this line of development is described in the preceding article.

Briefs : Materials
Low-Density, Ablative Resin-Impregnated Ceramic Insulation

Low-density, ablative thermal-protection panels can be made by impregnating fibrous ceramic substrates with organic polymers. With proper design and fabrication, these panels can protect temporarily against temperatures up to 3,500 °C or heat fluxes up to 16 MW/m2.

Briefs : Materials
Solar Heating for Deployment of Foam Structures

Solar heating has been proposed as a means of deployment of structures of the type described in "Cold Hibernated Elastic Memory (CHEM) Expandable Structures," (NPO-20394), NASA Tech Briefs, Vol. 23, No. 2 (February 1999), page 56. A few examples of structures that would be amenable to the CHEM...

Briefs : Materials
Fluorinated Diamondlike Carbon Coatings

Some experiments directed toward the development of improved hard, lubricious coating materials have involved direct fluorination of proprietary diamondlike coats on various substrates. The idea is to retain the hardness of the diamondlike material while adding surface molecular structures that impart the...

Briefs : Electronics & Computers
Ultra-Efficient Ka-Band MMIC Power Amplifier

A proposed monolithic microwave integrated circuit (MMIC) power amplifier has been designed to operate at frequencies around 28 GHz. According to a computer simulation of performance, this amplifier would operate at a power-added efficiency of more than 60 percent, which is more than 20 percent above...

Briefs : Electronics & Computers
Implementing Permutation Matrices by Use of Quantum Dots

Integrated circuits of a proposed type based on quantum-dot cellular automata (QCA) would implement permutation matrices. These circuits would serve as prototype building blocks for demonstrating the feasibility of quantum-dot-based computing and for the further development of increasingly...

Briefs : Software
Software for Concurrent Development of Reusable Software

The YaM computer program provides a conceptual framework (including configuration management) and a set of software tools that support the concurrent development of reusable software by members of a team. YaM favors development of software in modules that can be assembled into packages and...

Briefs : Software
Adaptive Problem Solving for Refining Control Strategy

A computer program implements an adaptive problem-solving (APS) algorithm for real-time development, refinement, and maintenance of the control strategy of an autonomous system that must operate in an environment about which little or no detailed information is available in advance. In the...

Briefs : Software
Advanced Software for Two-Phase Thermohydraulic Systems

Recent improvements in the SINDA/FLUINT computer program have made the program into a highly capable, commercially viable software product for general mathematical modeling of thermohydraulic systems. Versions of SINDA/FLUINT have been described in a number of previous NASA Tech Briefs...

Briefs : Software
Test Automation Software for AI Planning Software

This test automation software reduces the burden of testing artificial-intelligence (AI) planning software written in the Heuristic Scheduling Testbed System (HSTS) [a software architecture for planning and scheduling]. It automates what would otherwise be the labor intensive and...

Briefs : Software
Software for Simulation of 3D, Three-Phase Combusting Flow

A computational fluid dynamics (CFD) code has been developed to enable simulation of spray combustion near the fuel injectors in a liquid-fueled rocket engine. This code reflects the three-dimensional (3D), multiphase nature of the flow field in a rocket engine and is capable of modeling...

Briefs : Mechanical & Fluid Systems
Flex Wedges

Flex wedges have been proposed for use in brakes and clutches like those in which, heretofore, basic wedges have been used. Flex wedges (see Figure 1) offer advantages of superior braking and clutching performance and less weight, relative to basic wedges.

Briefs : Mechanical & Fluid Systems
Heat-Shield Panels in a 2D Shingling Arrangement

Figure 1 depicts mockups of lightweight metal heat-shield panels that have been proposed for use on spacecraft of the reusable-launch-vehicle type. These panels are designed for simplicity of insertion and removal. The design could also be adapted to both insulating and noninsulating panels in...

Briefs : Physical Sciences
Improved Automate System for Transferring Liquid Helium

An improved automated system for transferring liquid helium from a supply tank to an end-use cryostat has been proposed. Like automated systems developed previously for the same purpose, this system would reduce the time that must be spent by technicians in replenishing cryostats in...

Briefs : Physical Sciences
Algorithm for Computing Dynamics of Molecules

The Newton-Euler Inverse Mass Operator (NEIMO) algorithm and software that implements the algorithm have been developed to reduce the amount of time needed to perform computational simulations of the dynamics of macromolecules. The NEIMO algorithm and the associated software are intended, in...

Briefs : Physical Sciences
Improving Thin Foil X-Ray Mirrors

A proposal has been made to develop improved thin foil, replicated conical mirrors for use in x-ray astrophysics. In the NASA astrophysical programs in which such mirrors are used, they are required to be lightweight, and to offer moderate angular resolution and high throughput to afford required sensitivity in...

Briefs : Information Technology
An Improved Genetic Algorithm for Optimal Spacecraft Scheduling

A method of computing globally optimal schedules and plans in the face of possibly temporally varying constraints involves the use of an improved genetic algorithm. The method and computer program are directed toward the eventual use to schedule tasks to be performed on...

Briefs : Information Technology
Timeout Algorithm for Communications With Long Delays

A query timeout detection algorithm has been proposed to support a protocol for reliable communications over links that are characterized by long delays because of (1) propagation of signals over interplanetary distances and/or (2) intermittency. The protocol could be an interplanetary...

Briefs : Materials
Solar Sails Would Be Made From Carbon Nets

A report proposes that solar sails for spacecraft be made from nets of carbon fibers. The reason for choosing carbon nets over thin polymeric films is that nets offer greater capability for carrying tensile loads. The sails could be made from carbon-fiber nets of various thicknesses: nets used for...

Briefs : Materials
Solar Sails Would Be Segmented To Minimize Stresses

A report proposes that solar sails for spacecraft be constructed in segments in such a way as to minimize stresses. The segments could be made of metallized fabric or film and could be connected by short, strong tethers. Alternatively, the segments could be like islands, held loosely in...

Briefs : Mechanical & Fluid Systems
Modular Propulsion Clusters

A report proposes the development of modular propulsion clusters (MPCs) — small, self-contained propulsion systems that would be standardized, mass-produced, and readily installed on a variety of miniature future spacecraft. The MPCs would be inexpensive, "turn-key" alternatives to expensive conventional...

Briefs : Mechanical & Fluid Systems
Positioning System for a Human Habitat in a Large Centrifuge

A report describes the system for controlling the radial position and tilt of a spacecraftlike habitat for humans in NASA's Space Flight Environmental Simulator (SFES) — a 16-m-diameter centrifuge used previously to evaluate effects of hypergravitational acceleration on...

Briefs : Mechanical & Fluid Systems
Launch-on-Demand Servicing Microsatellites

A report describes an emerging class of miniature, highly capable, relatively inexpensive satellites that could be launched rapidly by nontraditional methods. Of particular interest is a subclass of proposed launch-on-demand microsatellites for inspecting and servicing other satellites (targets)...

Briefs : Physical Sciences
First-Generation Integrated Free-Flying Micro-Spacecraft

The concept of free-flying micro-spacecraft was to develop a miniature spacecraft system fully integrated with a scientific sensor. A fleet of such tiny spacecraft would be deployed in space for multi-probe measurements of a three-dimensional phenomenon and to separate the...

Briefs : Mechanical & Fluid Systems
Miniature Electrothermal Thruster

A report proposes a miniature electrothermal spacecraft engine. The engine would include a chamber with an inside length of ≈1.5 cm and inside diameter of ≈0.25 cm, with a dielectric (ideally diamond) sidewall lining, a metal-coated expansion nozzle at one end, and a metal electrode at the other end. A...

Briefs : Medical
Using Photosynthetic Bacteria To Make Oxygen on Mars

A report presents a proposal to harness photosynthetic bacteria to generate essential materials needed during human and robotic exploration on the surface of Mars. Utilizing an extremely small amount of H2O and an ample amount of CO2 (and N2 and/or...

Briefs : Physical Sciences
DNS of a Transitional Supercritical C7H16/N2 Mixing Layer

This report discusses direct numerical simulations (DNS) of a mixing layer, between a nitrogen stream and a heptane stream initially flowing at different velocities, under supercritical conditions and undergoing a transition to turbulence. Thermodynamically, supercritical conditions...

Briefs : Photonics/Optics
Commercial-Tolerance Superachromatic Near-IR Lens System

The figure depicts the optical layout and meridional-plane ray-trace diagram of a four-element superachromatic near-infrared (IR) lens system. The system features a 30-mm-diameter entrance pupil, a focal-length-to-diameter ratio (ƒ/ number) of 4, and a field of view with a...

Briefs : Motion Control
Subsurface-Explorer Robot With Spinning-Hammer Drive

A proposed robotic apparatus for underground exploration would propel itself downward in a percussive manner reminiscent of a jackhammer, pile driver, or hammer-and-chisel combination. Called a "subsurface explorer" (SSX), the apparatus (see figure) would include a hammer that would be moved...

Briefs : Photonics/Optics
Software for Multidisciplinary Concurrent Optical Design

The Integrated Optical Design Analyzer (IODA) is a computer program that facilitates multidisciplinary concurrent engineering of highly precise optical instruments. (IODA should not be confused with a multidisciplinary optical-system-analysis program, called "IMOS," that has been reported...

Briefs : Robotics, Automation & Control
Ultrasonic Detector and Identifier of Land Mines

A robotic apparatus equipped with ultrasonic probes and other instrumentation has been proposed to reduce the danger and cost and increase the speed of searching for land mines. The apparatus would implement modified versions of the proven techniques used by human searchers (delicately probing...

Briefs : Photonics/Optics
Multibeam Beacon Laser Assembly

An optical assembly that combines the output of mutually incoherent lasers into a multibeam source for transmission into free space was designed, assembled, and tested. This design was motivated by the need for ground-based beacon sources required for broadcasting laser beams to spaceborne, satellite-to-ground...

Briefs : Motion Control
Software for Selecting Modes of Vibration of a Structure

A computer program facilitates the selection of the dominant modes of vibration of a structure - especially the dominant modes that interact with specific locations on the structure. This program is intended for use in conjunction with any of the various vibration-mode-analysis programs...

Briefs : Photonics/Optics
Improved Fiber-Pigtailed Non-Planar Ring Oscillator Laser

An improved non-planar ring oscillator (NPRO) of the fiber-pigtailed type has been developed. The improvements over prior lasers of this type lie in details of design and construction that are intended to enhance mechanical stability and thereby increase the stability of optical...

Briefs : Photonics/Optics
Computing Atmospheric Profiles From Spectral Measurements

The SEASCRAPE computer program estimates the composition, temperature, and pressure of the atmosphere as a function of position by fitting remote-sounding spectroscopic data to a mathematical model of the transfer of radiation through the atmosphere. SEASCRAPE consists of two integrated...

Briefs : Photonics/Optics
Magnetically Actuated Miniature Paraboloidal Mirrors With Variable Radii of Curvature

Design and development of miniature paraboloidal mirrors that would be deflected magnetically to vary their radii of curvature (and thus their focal lengths) are under study. These mirrors, which belong to the class of microelectromechanical systems (MEMS),...

Briefs : Motion Control
Miniature Electroactive-Polymer Rakes

Miniature electroactive-polymer rakes (MEARs) are undergoing development for eventual use as simple, lightweight, inexpensive low-power-consumption devices that would remove soil, dust, and/or other loose particulate matter from the surfaces of solid objects. In the original intended application, MEARs is...

Briefs : Motion Control
Vibrational and Thermal Isolator for Spacecraft Electronics

Engineers at Johnson Space Center have invented a relatively inexpensive, lightweight device that provides vibrational and thermal isolation for low-power electronic equipment. The device was developed for use in outer space, where it has already proven successful in connection with...

Briefs : Photonics/Optics
Study of Stitching Errors in Shot-Shifted E-Beam Lithography

A report presents a study of the efficacy of shot shifting for reducing stitching errors in diffraction gratings made by electron-beam (E-beam) lithography. Stitching errors arise from fabricating a grating as a mosaic of smaller gratings by frequently translating the grating blank....


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