September 2001

Briefs : Mechanical & Fluid Systems
Variable-Specific-Impulse Magnetoplasma Rocket

Johnson Space Center has been leading the development of a high-power, electrothermal plasma rocket — the variable- specific-impulse magnetoplasma rocket (VASIMR) — that is capable of exhaust modulation at constant power. An electrodeless design enables the rocket to operate at power densities...

Briefs : Electronics & Computers
Current-Signature Sensor for Diagnosing Solenoid Valves

The "smart" current-signature sensor is an instrument that noninvasively measures and analyzes steady-state and transient components of the magnetic field of (and, thus, indirectly, the electric current in) a solenoid valve during normal operation. The instrument is being developed to...

Briefs : Electronics & Computers
Si Microsensor Baseplates With Low Parasitic Capacitances

An improved design for baseplates in silicon microsensors reduces parasitic capacitances between adjacent coplanar electrodes. It also reduces thermal-expansion mismatches, which are present in baseplates of older design.

Briefs : Mechanical & Fluid Systems
Carbon Nanotube Bimorph Actuators and Force Sensors

A proposal has been made to develop bimorph actuators and force sensors based on carbon nanotubes. The proposed devices could make it possible to generate, sense, and control displacements and forces on a molecular scale, and could readily be integrated with conventional electronic circuits....

Briefs : Physical Sciences
Built-in "Health Check" for Pressure Transducers

"Health check" would be built into pressure transducers, according to a proposal, to enable occasional, rapid, in situ testing of the transducers between normal pressure-measurement operations. The health check would include relatively simple devices that, upon command, would provide known...

Briefs : Electronics & Computers
Improvements in a Fast Transient-Voltage Recorder

Some improvements have been made in an instrument designed expressly for recording lightning-induced transient voltages on power and signal cables. The instrument as it existed prior to the improvements was described in "Fast Transient-Voltage Recorder" (KSC-11991), NASA Tech Briefs, Vol. 23,...

Briefs : Electronics & Computers
Improved Field-Emission Cathodes

Microscopic cathodes based on field emission (in contradistinction to thermionic emission) are undergoing development with a view toward using them as miniature or scalable sources of electrons in diverse applications that could include spacecraft thrusters, semiconductor-fabrication equipment, flat-panel...

Briefs : Software
LabVIEW as Flight Software With VxWorks Operating System

A development effort under way at the time of reporting the information for this article is directed toward producing a version of the LabVIEW data-acquisition software that would be suitable for use as flight software that could be executed in the VxWorks real-time operating system....

Briefs : Mechanical & Fluid Systems
Robot for Positioning Sensors in a Plant-Growth Chamber

The Advanced Life Support Automated Remote Manipulator (ALSARM) is a three-degree-of-freedom robotic system that positions an array of sensors inside a closed-system hydroponic chamber used in research on the production of biomass and the use of hydroponic subsystems of life-support...

Briefs : Software
MPP Port of PVM to a Beowulf Computer System

The latest version of the Parallel Virtual Machine (PVM) computer program, denoted PVM 3.4.3, incorporates a massively-parallel-processor (MPP) software port that enables a user working on a computer outside a Beowulf system (a cluster of personal computers that run the Linux operating system) to...

Briefs : Software
Software for Iterative Optimization of Plans

The Iterative Plan Optimization computer program automatically optimizes plans with respect to preferences expressed by human planners. This program incorporates a generalization of commonly occurring plan-quality metrics to provide a language for expression of preferences. The program...

Briefs : Software
Software for Planning an SAR Antarctic Mapping Mission

The AMM Automated Mission Planner computer program was developed to save time and money by automating much of the planning of the Second RADARSAT Antarctic Mapping Mission (AMM), which was scheduled to take place at the time of writing this article. The planning problem for this and...

Briefs : Materials
Predicting Stresses in Thermal-Barrier Coatings

A methodology for predicting stresses and the resultant cracking in plasma-sprayed thermal-barrier coatings (TBCs) has been developed. The methodology is built around a computer code that implements a finite-element model that simulates the evolution of stresses, strains, and related phenomena in a...

Briefs : Materials
Enhancing the Removal of Chlorocarbons From Groundwater

Experiments have shown that ultrasound could be an effective means of enhancing the removal of chlorinated hydrocarbon contaminants from groundwater by the zero-valent-metal treatment process. This process, which has been a subject of research in recent years, is attractive because it does...

Briefs : Mechanical & Fluid Systems
Magnetic/Extendible Boom Mechanism for Docking of Spacecraft

The magnetic/extendible boom docking aid is an improved mechanism that enables two spacecraft to capture and structurally mate with each other without inducing the large (and frequently excessive) loads encountered in docking by use of prior docking mechanisms. The capability afforded...

Briefs : Mechanical & Fluid Systems
Vapor-Compression Solar Refrigerator Without Batteries

A solar-powered vapor-compression refrigeration system developed for Johnson Space Center operates without batteries. The design of this system will make the cost of solar-powered refrigeration systems competitive and enable the use of such systems in long-distance spaceflights, military...

Briefs : Manufacturing & Prototyping
Thermal-Stress Technique for Cutting Thin Glass Sheets

A technique based on the generation of highly localized thermal stresses has been devised as a means of cutting both flat and curved glass sheets of thicknesses between 30 and 600 µm. The technique is reliable, accurate, and economical. The technique can be used, for example, to cut thin...

Briefs : Medical
Microwave-Sterilizable Access Port

The microwave-sterilizable access port is an apparatus that functions in a simple, quick, and reliable manner to reduce significantly the risk of contamination during transfer of materials into or out of bioreactors or other microbially vulnerable closed systems. A major improvement over equipment developed...

Briefs : Medical
Treatment With Ferrates Eliminates DNA and Proteins

Ferrate (VI) salts have been proposed for use in sterilizing water (perhaps also in sterilizing air). The iron in ferrate (VI) salts is in its highest oxidation state (VI), and these salts are extremely strong oxidants. In laboratory experiments, it was shown that treatment of DNA solutions...

Briefs : Physical Sciences
All-Pressure Fluid-Drop Model Applied to a Binary Mixture

A report presents a computational study of the subcritical and supercritical behaviors of a drop of heptane surrounded by nitrogen, using the fluid-drop model described in "Model of a Drop of O2 Surrounded by H2 at High Pressure" (NPO-20220) and "The Lewis Number...

Briefs : Physical Sciences
Validation of All-Pressure Fluid-Drop Model

A report presents a computational study of the subcritical and supercritical behaviors of a drop of heptane surrounded by nitrogen. The subject matter is basically same as that of the report described in the preceding article, except that the Lewis-number issue is not addressed in detail; however, this...

Briefs : Information Technology
Generating Commands for the Mars Polar Lander Robotic Arm

A report discusses the use of the Web Interface for Telescience (WITS) for visualization and command sequence generation in the Mars Polar Lander (MPL) mission. WITS, which has been described in prior articles in NASA Tech Briefs, is an Internet-based software system that enables...

Briefs : Electronics & Computers
The Future of Electronic Device Design

An article discusses anticipated advances in the design of increasingly capable integrated circuits containing ever smaller electronic devices. The article emphasizes the emergence of technology computer-aided design (TCAD) — a discipline in which computer-aided design is combined with computational...

Briefs : Materials
Multi-Shock Blankets for Protecting Spacecraft

A report discusses multi-shock blankets, which are under investigation for use in protecting spacecraft against orbiting debris from prior spacecraft missions. Multi-shock blankets are described in comparison with early protective metallic "bumpers" and with a somewhat more recent invention called...

Briefs : Mechanical & Fluid Systems
Airlocks for Pressurized Rovers

A report presents a survey of the design engineering and scientific literature on airlocks and on planetary-exploration vehicles ("rovers"), from the perspective of evaluating existing and potential design concepts for airlocks for pressurized rovers. The airlocks are the key to designing a pressurized rover...

Briefs : Medical
Spacecraft-Facility Microbes Tolerate H2O2, NaCl, and Heat

A report describes experiments that were performed to isolate and characterize microbes that survive conditions of controlled circulation of air, desiccation, low nutrient concentrations, and moderately high temperatures in a spacecraft-assembly facility. These conditions are more severe...

Briefs : Materials
Study of High-Performance Polyimide Foams

This report describes an experimental study of thermal-stability, mechanical, and flammability properties of foams of several different densities made of three different polyimides. The study was performed because (1) prior such studies were performed on polyimide films rather than foams and (2)...

Briefs : Physical Sciences
Subgrid Analysis of Mixing Layer With Evaporating Droplets

This report presents an analysis of a database from computational simulations of a droplet-laden mixing layer (i.e., evaporating droplets of a liquid fuel in air) undergoing a transition to turbulence. The basic governing equations were those of transport of discrete droplets through a...

Briefs : Physical Sciences
Validated Model of a Fluid Drop for All Pressures

The report "A Validated All-Pressure Fluid Drop Model and Lewis Number Effects for a Binary Mixture" presents one in a series of theoretical and computational studies of the subcritical and subpercritical behaviors of a drop of fluid and, in particular, a drop of heptane surrounded by nitrogen...

Briefs : Photonics/Optics
Closed-Loop Microsphere Laser for Optoelectronic Oscillator

A prototype ring laser in which a transparent microsphere serves as an electromagnetic-mode selector has been constructed in a continuing effort to develop optoelectronic oscillators for generating light signals amplitude-modulated by microwave signals, all with low phase noise....

Briefs : Physical Sciences
Photonic Switching Devices Using Light Bullets

A class of proposed photonic switching devices would utilize interactions among light bullets that have been studied theoretically. Because they function at speeds much greater than those of electrically, magnetically, and acoustically actuated switching devices, these and other photonic switching...

Briefs : Photonics/Optics
Miniature Optoelectronic Oscillators Based on Microspheres

The figure depicts an example of a proposed type of optoelectronic oscillator (OEO) based on some of the same principles as those described in the preceding article. In the proposed OEOs as in the OEOs of the preceding article, transparent (e.g., glass) microspheres that exhibit...

Briefs : Photonics/Optics
Low-Power Shutter Mechanism for a Cryogenic Infrared Camera

An assembly that includes electromechanical rotary actuators has been developed specifically for use as the shutter mechanism of a cryogenic infrared camera that will be part of an astronomical telescope. The camera will be cooled, by use of superfluid helium, to an operating...

Briefs : Photonics/Optics
Optoelectronic Oscillators Based on Fiber-Optic Resonators

Optoelectronic oscillators (OEOs) of a proposed type would be based partly on the use of fiber-optic linear or ring resonators in place of the long fiber-optic delay lines that have been used to obtain low phase noise in some previously developed OEOs. Although the proposal to use...