Special Coverage

Technique Provides Security for Multi-Robot Systems
Bringing New Vision to Laser Material Processing Systems
NASA Tests Lasers’ Ability to Transmit Data from Space
Converting from Hydraulic Cylinders to Electric Actuators
Automating Optimization and Design Tasks Across Disciplines
Vibration Tables Shake Up Aerospace and Car Testing
Supercomputer Cooling System Uses Refrigerant to Replace Water
Computer Chips Calculate and Store in an Integrated Unit
Electron-to-Photon Communication for Quantum Computing

Method for Detecting Perlite Compaction in Large Cryogenic Tanks

This technique could be applied by companies using rail cars and trucks to deliver liquid cryogens.

Perlite is the most typical insulating powder used to separate the inner and outer shells of cryogenic tanks. The inner tank holds the low-temperature commodity, while the outer shell is exposed to the ambient temperature. Perlite minimizes radiative energy transfer between the two tanks. Being a powder, perlite will settle over time, leading to the danger of transferring any loads from the inner shell to the outer shell. This can cause deformation of the outer shell, leading to damaged internal fittings.

Posted in: Briefs, TSP, Physical Sciences, Finite element analysis, Sensors and actuators, Containers, Insulation

Directional Spherical Cherenkov Detector

Incident particles could be sorted by direction, speed, and electric charge.

A proposed radiation-detecting apparatus would provide information on the kinetic energies, directions, and electric charges of highly energetic incident subatomic particles. The apparatus was originally intended for use in measuring properties of cosmic rays in outer space, but could also be adapted to terrestrial uses — for example, radiation dosimetry aboard high-altitude aircraft and in proton radiation therapy for treatment of tumors.

Posted in: Briefs, TSP, Physical Sciences, Sensors and actuators, Medical equipment and supplies, Radiation, Test equipment and instrumentation

Using Thin-Film Thermometers as Heaters in Thermal Control Applications

A cryogenic sensor maintains calibration at ≈4.2 K to better than 2 mK (

Posted in: Briefs, TSP, Physical Sciences, Sensors and actuators, Thermal management

System for Hydrogen Sensing

A low-power, wireless gas-sensing system is designed to safeguard the apparatus to which it is attached, as well as associated personnel. It also ensures the efficiency and operational integrity of the hydrogen-powered apparatus. This sensing system can be operated with lower power consumption (less than 30 nanowatts), but still has a fast response. The detecting signal can be wirelessly transmitted to remote locations, or can be posted on the Web. This system can also be operated by harvesting energy.

The electrical signal response of the sensor to the hydrogen gas can be amplified by a differential detection interface (DDI) connected to the low-power gas sensor. A microcontroller is connected and programmed to process the electrical signal, which is then wirelessly transmitted. The system also includes a central monitoring station with a wireless receiver configured to receive the sensor data signal from the wireless transmitter of the sensor device. The system further includes a power source with at least one vibrational energy harvester, solar energy harvester, and a battery.

This work was done by Jenshan Lin, David P. Norton, Stephen J. Pearton, and Fan Ren of the University of Florida for Glenn Research Center. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Physical Sciences category.

Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center, Innovative Partnerships Office, Attn: Steve Fedor, Mail Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. Refer to LEW-18484-1.

Posted in: Briefs, TSP, Physical Sciences, Sensors and actuators, Hydrogen fuel, Gases, Reliability, Fueling safety

K-Band Traveling-Wave Tube Amplifier

This amplifier can be used for high-data-rate transmission from communications satellites.

A new space-qualified, high-power, high-efficiency, K-band traveling-wave tube amplifier (TWTA), shown in the figure, will provide high-rate, high-capacity, direct-to-Earth communications for science data and video gathered by the Lunar Reconnaissance Orbiter (LRO) during its mission. The TWTA is designed for 20 years of operational life, well in excess of the expected 7 years of mission life. It is a vacuum electronics device that is used to amplify microwave communications signals. TWTs are needed for high-frequency and high-power applications, such as communications from the Moon, because they have significantly higher power capability and efficiency than solid-state devices. Amplification in a TWT is by a factor of about 100,000. The RF power and data rate values for the LRO TWTA, when compared with other space based K-band transmitters, are an order of magnitude higher and represent a new state of the art.

Posted in: Briefs, Electronics & Computers, Amplifiers, Waveguides, Wireless communication systems, Satellites

Sideband-Separating, Millimeter-Wave Heterodyne Receiver

Researchers have demonstrated a sub-millimeter-wave spectrometer that combines extremely broad bandwidth with extremely high sensitivity and spectral resolution to enable future spacecraft to measure the composition of the Earth’s troposphere in three dimensions many times per day at spatial resolutions as high as a few kilometers. Microwave limb sounding is a proven remote-sensing technique that measures thermal emission spectra from molecular gases along limb views of the Earth’s atmosphere against a cold space background.

Posted in: Briefs, TSP, Electronics & Computers, Radio equipment, Remote sensing, Product development, Thermal testing, Spacecraft

Simplified Load-Following Control for a Fuel Cell System

A load-dependent voltage would be used to control a parasitic device.

A simplified load-following control scheme has been proposed for a fuel cell power system. The scheme could be used to control devices that are important parts of a fuel cell system but are sometimes characterized as parasitic because they consume some of the power generated by the fuel cells.

Posted in: Briefs, Electronics & Computers, Electronic control systems, Energy consumption, Fuel cells

Loosely Coupled GPS-Aided Inertial Navigation System for Range Safety

The Autonomous Flight Safety System (AFSS) aims to replace the human element of range safety operations, as well as reduce reliance on expensive, downrange assets for launches of expendable launch vehicles (ELVs). The system consists of multiple navigation sensors and flight computers that provide a highly reliable platform. It is designed to ensure that single-event failures in a flight computer or sensor will not bring down the whole system. The flight computer uses a rules-based structure derived from range safety requirements to make decisions whether or not to destroy the rocket.

Posted in: Briefs, Electronics & Computers, Flight guidance systems, Global positioning systems, Global positioning systems (GPS), Systems engineering, Expendable launch vehicles

Modified Phasemeter for a Heterodyne Laser Interferometer

An FPGA-based design could be exported to other heterodyne laser interferometers.

Modifications have been made in the design of instruments of the type described in “Digital Averaging Phasemeter for Heterodyne Interferometry” (NPO-30866), NASA Tech Briefs, Vol. 28, No. 9 (September 2004), page 6a. To recapitulate: A phasemeter of this type measures the difference between the phases of the unknown and reference heterodyne signals in a heterodyne laser interferometer. This phasemeter performs well enough to enable interferometric measurements of displacements with accuracy of the order of 100 pm. This is a single, integral system capable of performing three major functions that, heretofore, have been performed by separate systems: (1) measurement of the fractional-cycle phase difference, (2) counting of multiple cycles of phase change, and (3) averaging of phase measurements over multiple cycles for improved resolution. This phasemeter also offers the advantage of making repeated measurements at a high rate: the phase is measured on every heterodyne cycle. Thus, for example, in measuring the relative phase of two signals having a heterodyne frequency of 10 kHz, the phasemeter would accumulate 10,000 measurements per second. At this high measurement rate, an accurate average phase determination can be made more quickly than is possible at a lower rate.

Posted in: Briefs, TSP, Electronics & Computers, Architecture, Lasers, Performance upgrades, Reliability

Coaxial Propellant Injectors With Faceplate Annulus Control

These injectors are simpler and less expensive, relative to prior coaxial injectors.

An improved design concept for coaxial propellant injectors for a rocket engine (or perhaps for a non-rocket combustion chamber) offers advantages of greater robustness, less complexity, fewer parts, lower cost, and less bulk, relative to prior injectors of equivalent functionality. This design concept is particularly well suited to small, tight-tolerance injectors, for which prior designs are not suitable because the practical implementation of those designs entails very high costs and difficulty in adhering to the tolerances.

Posted in: Briefs, Manufacturing & Prototyping, Propellants, Fuel injection, Rocket engines

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