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

High-Precision Shape Control of In-Space Deployable Large Membrane/Thin-Shell Reflectors

Real-time reflector surface figure control uses piezoelectric polymer actuators.

This innovation has been developed to improve the resolutions of future spacebased active and passive microwave antennas for earth-science remote sensing missions by maintaining surface figure precisions of large membrane/thinshell reflectors during orbiting. The intention is for these sensing instruments to be deployable at orbit altitudes one or two orders of magnitude higher than Low Earth Orbit (LEO), but still being able to acquire measurements at spatial resolution and sensitivity similar to those of LEO. Because active and passive microwave remote sensors are able to penetrate through clouds to acquire vertical profile measurements of geophysical parameters, it is desirable to elevate them to the higher orbits to obtain orbital geometries that offer large spatial coverage and more frequent observations. This capability is essential for monitoring and for detailed understanding of the life cycles of natural hazards, such as hurricanes, tropical storms, flash floods, and tsunamis.

Posted in: Briefs, Mechanical Components, Mechanics, Antennas, Remote sensing, Weather and climate

Rapid Active Sampling Package

A field-deployable, battery-operated tool enables rock sampling in the field.

A field-deployable, battery-powered Rapid Active Sampling Package (RASP), originally designed for sampling strong materials during lunar and planetary missions, shows strong utility for terrestrial geological use. The technology is proving to be simple and effective for sampling and processing materials of strength. Although this originally was intended for planetary and lunar applications, the RASP is very useful as a powered hand tool for geologists and the mining industry to quickly sample and process rocks in the field on Earth.

Posted in: Briefs, Mechanical Components, Mechanics, Soils, Tools and equipment, Test equipment and instrumentation, Mining vehicles and equipment

Miniature Lightweight Ion Pump

This lightweight pump with no moving parts eliminates the need for a backup pump.

This design offers a larger surface area for pumping of active gases and reduces the mass of the pump by eliminating the additional vacuum enclosure. There are three main components to this ion pump: the cathode and anode pumping elements assembly, the vacuum enclosure (made completely of titanium and used as the cathode and maintained at ground potential) containing the assembly, and the external magnet. These components are generally put in a noble diode (or differential) configuration of the ion pump technology. In the present state of the art, there are two cathodes, one made of titanium and the other of tantalum. The anodes are made up of an array of stainless steel cylinders positioned between the two cathodes.

Posted in: Briefs, Mechanical Components, Mechanics, Product development, Gases, Pumps

Cryogenic Transport of High-Pressure-System Recharge Gas

Advantages include low pressure and high density during transport.

A method of relatively safe, compact, efficient recharging of a high-pressure room-temperature gas supply has been proposed. In this method, the gas would be liquefied at the source for transport as a cryogenic fluid at or slightly above atmospheric pressure. Upon reaching the destination, a simple heating/expansion process would be used to (1) convert the transported cryogenic fluid to the room-temperature, high-pressure gaseous form in which it is intended to be utilized and (2) transfer the resulting gas to the storage tank of the system to be recharged.

Posted in: Briefs, TSP, Physical Sciences, Gases, Refueling, Fueling safety

Water-Vapor Raman Lidar System Reaches Higher Altitude

Signal-to-noise ratios are increased over those of prior such systems.

A Raman lidar system for measuring the vertical distribution of water vapor in the atmosphere is located at the Table Mountain Facility (TMF) in California. Raman lidar systems for obtaining vertical water-vapor profiles in the troposphere have been in use for some time. The TMF system incorporates a number of improvements over prior such systems that enable extension of the altitude range of measurements through the tropopause into the lower stratosphere.

Posted in: Briefs, TSP, Physical Sciences, Measurements, Lidar, Humidity

Compact Ku-Band T/R Module for High-Resolution Radar Imaging of Cold Land Processes

This module can be used in phased-array antennas for radar or communications.

Global measurement of terrestrial snow cover is critical to two of the NASA Earth Science focus areas: (1) climate variability and change and (2) water and energy cycle. For radar backscatter measurements, Ku-band frequencies, scattered mainly within the volume of the snowpack, are most suitable for the SWE (snow-water equivalent) measurements. To isolate the complex effects of different snowpack (density and snowgrain size), and underlying soil properties and to distinctly determine SWE, the space-based synthetic aperture radar (SAR) system will require a dual-frequency (13.4 and 17.2 GHz) and dual-polarization approach.

Posted in: Briefs, Physical Sciences, Antennas, Radar, Cold weather, Soils, Water, Weather and climate

Performance Bounds on Two Concatenated, Interleaved Codes

It is now possible to calculate tight bounds at high SNR.

A method has been developed of computing bounds on the performance of a code comprised of two linear binary codes generated by two encoders serially concatenated through an interleaver. Originally intended for use in evaluating the performances of some codes proposed for deep-space communication links, the method can also be used in evaluating the performances of short-block-length codes in other applications.

Posted in: Briefs, TSP, Information Sciences, Communication protocols, Wireless communication systems, Performance tests, Test procedures

Mission Reliability Estimation for Repairable Robot Teams

An analytical model demonstrates autonomous and intelligent control systems capable of operating distributed, multi-planetary surface vehicles for scouting or construction.

A mission reliability estimation method has been designed to translate mission requirements into choices of robot modules in order to configure a multi-robot team to have high reliability at minimal cost. In order to build cost- effective robot teams for long-term missions, one must be able to compare alternative design paradigms in a principled way by comparing the reliability of different robot models and robot team configurations. Core modules have been created including: a probabilistic module with reliability-cost characteristics, a method for combining the characteristics of multiple modules to determine an overall reliability-cost characteristic, and a method for the generation of legitimate module combinations based on mission specifications and the selection of the best of the resulting combinations from a cost-reliability standpoint.

Posted in: Briefs, TSP, Information Sciences, Mathematical analysis, Fleet management, Cost analysis, Robotics, Reliability

Algorithm for Stabilizing a POD-Based Dynamical System

This algorithm provides a new way to improve the accuracy and asymptotic behavior of a low-dimensional system based on the proper orthogonal decomposition (POD). Given a data set representing the evolution of a system of partial differential equations (PDEs), such as the Navier-Stokes equations for incompressible flow, one may obtain a low-dimensional model in the form of ordinary differential equations (ODEs) that should model the dynamics of the flow. Temporal sampling of the direct numerical simulation of the PDEs produces a spatial time series. The POD extracts the temporal and spatial eigen-functions of this data set. Truncated to retain only the most energetic modes followed by Galerkin projection of these modes onto the PDEs obtains a dynamical system of ordinary differential equations for the time-dependent behavior of the flow.

Posted in: Briefs, Information Sciences, Computational fluid dynamics, Mathematical analysis, Mathematical models

Parameterizing Coefficients of a POD-Based Dynamical System

This parameterization enables accurate prediction of temporal evolution of certain flow dynamics.

A method of parameterizing the coefficients of a dynamical system based of a proper orthogonal decomposition (POD) representing the flow dynamics of a viscous fluid has been introduced. (A brief description of POD is presented in the immediately preceding article.) The present parameterization method is intended to enable construction of the dynamical system to accurately represent the temporal evolution of the flow dynamics over a range of Reynolds numbers.

Posted in: Briefs, Information Sciences, Computational fluid dynamics, Mathematical models

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