Search

Only a small portion of a hyperspectral image is useful to identify any given material. The sheer volume of data in the image causes many material classification programs to run slowly and produce poor results, as they search the full image dataset for the information they need. The same algorithm can produce more accurate results in less time if it is given a reduced dataset that contains only the information most useful for detecting the target material. This technology is a system that creates reduced datasets tailored for each potential application. The system can operate on archived hyperspectral imagery from NASA's EO-1 Hyperion instrument or on data from future missions, such as the Hyperspectral Infrared Imager (HyspIRI), as they become operational. Other agencies with hyperspectral imagers, including the defense and intelligence communities, can also use the system in their applications. Additionally, the system can operate on-board these spacecraft, allowing them to quickly and autonomously analyze the imagery they collect. Spacecraft with this capability could detect emerging situations and then intelligently re-task themselves to collect more data, or alert scientists or emergency personnel on the ground. This innovation includes an algorithm to convert hyperspectral images to a progressive format, along with another algorithm to quickly analyze hyperspectral images in this progressive format and select the most important bands for a given science application.

An array of carbon nanotubes (CNTs) in a substrate is connected to a variable-pulse voltage source. The CNT tips are spaced appropriately from the second electrode maintained at a constant voltage. A sequence of voltage pulses is applied and a pulse discharge breakdown threshold voltage is estimated for one or more gas components, from an analysis of the current-voltage characteristics. Each estimated pulse discharge breakdown threshold voltage is compared with known threshold voltages for candidate gas components to estimate whether at least one candidate gas component is present in the gas. The procedure can be repeated at higher pulse voltages to estimate a pulse discharge breakdown threshold voltage for a second component present in the gas. The CNTs in the gas sensor have a sharp (low radius of curvature) tip; they are preferably multiwall carbon nanotubes (MWCNTs) or carbon nanofibers (CNFs), to generate high-strength electrical fields adjacent to the current collecting plate, such as a gold plated silicon wafer or a stainless steel plate for breakdown of the gas components with lower voltage application and generation of high current. The sensor system can provide a high-sensitivity, low-power-consumption tool that is very specific for identification of one or more gas components. The sensors can be multiplexed to measure current from multiple CNT arrays for simultaneous detection of several gas components.

A resistor-type sensor was fabricated which has a network of cross-linked SWCNTs with purity over 99%. An ordinary cellulose paper used for filtration was employed as the substrate. The filter paper exhibits medium porosity with a flow rate of 60 mL/min and particle retention of 5-10m. The roughness and porosity of the papers are attractive because they increase the contact area with the ambient air and promote the adhesion to carbon nanotubes. The SWCNTs were functionalized with carboxylic acid (COOH) to render them hydrophilic, thus increasing the adhesion with the substrate. The functionalized SWCNTs were dispersed in dimethylformamide solution. The film composed of networks of cross-linked CNTs was formed using drop-cast coating followed by evaporation of the solvent. Adhesive copper foil tape was used for contact electrodes. Our sensors outperformed the oxide nanowire-based humidity sensors in terms of sensitivity and response/recovery times.

This invention is a system and associated method for causing a fine-grained powder in a sample holder to undergo at least one of three motions (vibration, rotation or translation) at a selected motion frequency in order to expose a statistically relevant population of grains in random orientation to a diffraction or fluorescent source. One or more measurements of diffraction, fluorescence, spectroscopic interaction, transmission, absorption and/or reflection can be made on the sample, using x-rays or light in a selected wavelength region. In one embodiment, the invention allows the relaxation of sample preparation and handling requirements for powder X-ray Diffraction (pXRD). The sample, held between two thin plastic windows, undergoes granular convection similar to a heated liquid, causing the individual grains to move past a collimated X-ray beam in random orientation over time. The result is an X-ray diffraction pattern having the correct diffracted intensities without a requirement for specialized mechanical motions. A major improvement over conventional sample preparation and handling techniques for pXRD is the potential to characterize larger grain-size material, resulting in a significant relaxation of the constraints on sample preparation (grinding). The powder handling system as described extends the range of useful grain sizes for XRD/ X-ray fluorescence (XRF) from a few micrometers (m) to several hundred m. Inclusion of the powder handling system enables automated instruments such as CheMin, a robotic XRD/XRF instrument designed and developed by NASA, to analyze as-received or coarsely powdered samples on NASAs Mars Science Laboratory rover, or in extreme, toxic or hazardous environments on Earth.

These connectors are designed to be used in harsh environments and to withstand rough handling, such as being stepped on or rolled over by wheelbarrows or light vehicles. If the demated connectors are dropped or placed on the ground, the end caps will shield them from damage and contaminants. When mated, the seal between the housings and end caps keeps contaminants out. The end caps are latched to the housings so that the caps cannot be unintentionally opened; this latch can be opened only by depressing the levers. The spring used to open or close the cap is constructed of a shape memory alloy, allowing the cap to be opened and closed an almost infinite number of times. The cap actuation levers are designed so that only a 3/4-inch pull is needed to open the cap a full 190 degrees. The housings can accept most commercial-off-the-shelf electrical or fluid connectors (including those designed for cryogenics), thus eliminating the need for specialized connectors in hostile environments. The housings can also be grounded and scaled up or down to accommodate connectors of different sizes. The housings can be constructed of steel, aluminum, composites, or even plastic, depending on the environment in which they will be used and material cost constraints.

The low-temperature oxidation catalyst technology employs a novel catalyst formulation, termed platinized tin oxide (Pt/SnOx). The catalysts can be used on silica gel and cordierite catalyst supports, and the latest developments provide sprayable formulations for use on a range of support types and shapes. Originally developed for removal of CO, the catalyst has also proven effective for removal of formaldehyde and other lightweight hydrocarbons. NASA researchers have also extended the capability to include reduction of NOx as well as developed advanced chemistries that stabilized the catalyst for automotive catalytic converters via the engineered addition of other functional components. These catalyst formulations operate at elevated temperatures and have performed above the EPA exhaust standards for well beyond 25,000 miles. In addition, the catalyst can be used in diesel engines because of its ability to operate over an increased temperature range. For use as a gas sensor, the technology takes advantage of the exothermic nature of the catalytic reaction to detect formaldehyde, CO, or hydrocarbons, with the heat being produced proportional to the amount of analyte present.

Langley has developed various technologies to enable the portable detection system, including: - 3-inch electret condenser microphone - unprecedented sensitivity of -45 dB/Hz - compact nonporous windscreen - suitable for replacing spatially demanding soaker hoses in current use - infrasonic calibrator for field use - piston phone with a test signal of 110 dB at 14Hz. - laboratory calibration apparatus - to very low frequencies - vacuum isolation vessel - sufficiently anechoic to permit measurement of background noise in microphones at frequencies down to a few Hz - mobile source for reference - a Helmholtz resonator that provides pure tone at 19 Hz The NASA system uses a three-element array in the field to locate sources of infrasound and their direction. This information has been correlated with PIREPs available in real time via the Internet, with 10 examples of good correlation.

Large aircraft can generate air vortices in their wake, turbulence that can prove hazardous to aircraft that follow too closely. Because wake vortices are invisible, all takeoffs at busy airports are spaced several minutes apart. This separation gives the vortices time to dissipate, even though they only occur 10% of the time, with resulting loss of operational efficiency. Similarly, clear air turbulence is invisible and can also be hazardous to aircraft. By detecting such disturbances through their infrasound emissions, precautions can be taken to avoid them. Other phenomena can be detected through infrasound, including tornadoes, helicopters on the other side of mountains, underground nuclear explosions and digging tunnels. Through the unique properties of infrasound, many of these can be detected from hundreds of miles away. NASA's infrasound sensor is a highly refined microphone that is capable of detecting acoustic waves from 20 Hz down to dc, the infrasound range. The design is robust and compact, eliminating the bulk and weight found in other technologies. Where most alternative methods are restricted to certain weather conditions and locations, the NASA sensor filters noise from wind and other sources, allowing its use under any weather or geographic conditions.

The MiDAR transmitter emits coded narrowband structured illumination to generate high-frame-rate multispectral video, perform real-time radiometric calibration, and provide a high-bandwidth simplex optical data-link under a range of ambient irradiance conditions, including darkness. A theoretical framework, based on unique color band signatures, is developed for multispectral video reconstruction and optical communications algorithms used on MiDAR transmitters and receivers. Experimental tests demonstrate a 7-channel MiDAR prototype consisting of an active array of multispectral high-intensity light-emitting diodes (MiDAR transmitter) coupled with a state-of-the-art, high-frame-rate NIR computational imager, the NASA FluidCam NIR, which functions as a MiDAR receiver. A 32-channel instrument is currently in development. Preliminary results confirm efficient, radiometrically-calibrated, high signal-to-noise ratio (SNR) active multispectral imaging in 7 channels from 405-940 nm at 2048x2048 pixels and 30 Hz. These results demonstrate a cost-effective and adaptive sensing modality, with the ability to change color bands and relative intensities in real-time, in response to changing science requirements or dynamic scenes. Potential applications of MiDAR include high-resolution nocturnal and diurnal multispectral imaging from air, space and underwater environments as well as long- distance optical communication, bidirectional reflectance distribution function characterization, mineral identification, atmospheric correction, UV/fluorescent imaging, 3D reconstruction using Structure from Motion (SfM), and underwater imaging using Fluid Lensing. Multipurpose sensors, such as MiDAR, which fuse active sensing and communications capabilities, may be particularly well-suited for mass-limited robotic exploration of Earth and the solar system and represent a possible new generation of instruments for active optical remote sensing.

A typical sensor device includes a set of interdigitated microelectrodes fabricated by photolithography on silicon wafer or an electrically insulating substrate. In preparation for fabricating the SWCNT portion of such a sensor, a batch of treated (coated or doped) SWCNTs is dispersed in a solvent. The resulting suspension of SWCNTs is drop-deposited or injected onto the area containing the interdigitated electrodes. As the solvent evaporates, the SWCNTs form a mesh that connects the electrodes. The density of the SWCNTs in the mesh can be changed by varying the concentration of SWCNTs in the suspension and/or the amount of suspension dropped on the electrode area. To enable acquisition of measurements for comparison and to gain orthogonality in the sensor array, undoped SWCNTs can be similarly formed on another, identical set of interdigitated electrodes. Coating materials tested so far include chlorosulfonated polyethylene. Dopants that have been tested include Pd, Pt, Au, Cu and Rh nanoparticle clusters. To date, the sensor has been tested for NO2, NH3, CH4, Cl2, HCl, toluene, benzene, acetone, formaldehyde and nitrotoulene.