SEARCH · Engineering Papers
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The Next-Generation Precipitation Radar (PR-2) prototyped by NASA/JPL will depend heavily on high-performance digital processing to collect meaningful echo data.
The Next-Generation Precipitation Radar prototyped by NASA/JPL will depend heavily on high performance digital processing to collect meaningful rain echo data.
This paper describes a new process of performing online documentation for large complex projects.
The Planetary Data System Imaging Node maintains and distributes the archives of planetary image data acquired from NASA's flight projects with the primary goal of enabling the science community to perform image processing and analysis on the data. The Node provides direct and easy access to the digital image archives through wide distribution of the data on CD-ROM media and on-line remote-access tools by way of Internet services.
A research program is underway to establish the feasibility of fabricating 15 cm diameter ion engine optics from polycrystalline diamond film. Because of its high thermal conductivity, low CTE, and low sputter yield, diamond film has the potential of mitigating life limiting and performance degrading processes which have hindered flight qualification of ion thrusters to date. Results of experiments are reported.
Explore the source record for details and available documents.
One option under current study for the Terrestrial Planet Finder-Occulter (TPF-O) observatory shares some key features of the Hubble Space Telescope (HST). Both are space telescopes with a primary mirror aperture of around 2.4 meters and designed to observe in the visible to near infrared range of wavelengths, with the major difference in science capability being that TPF-O has an areal FOV on the order of 100 times larger than that of HST. This larger FOV, whose science camera is also expected to provide fine guidance, and other mission differences, mean that most TPF-O SC bus subsystems will have very different requirements than those of HST. Unlike HST in LEO, TPF-O is designed to operate in an orbit around the Sun-Earth lagrange 2 (SEL2) point. The longer communications range to SEL2 and the large FOV require much higher performance data processing and communications than HST. Maintaining a SEL2 orbit requires TPF-O, unlike HST, to have a propulsion system. TPF-O will have a specialized tracking system that allows the formation flying occulter to maintain its required position. However, despite these additional features, the velocity required for reaching SEL2 and the limited capabilities of affordable launch vehicles require TPF-O to have a compact and low-mass design relative to HST. Finally, TPF-O may utilize a modular design to reduce development cost and, if it required, allow servicing using approaches different from those of HST.
A CMOS time-of-flight TOF system-on-a-chip SoC for precise time interval measurement with low power consumption and high counting rate has been developed. The analog and digital TOF chip may include two Constant Fraction Discriminators CFDs and a Time-to-Digital Converter TDC. The CFDs can interface to start and stop anodes through two preamplifiers and perform signal processing for time walk compensation (110). The TDC digitizes the time difference with reference to an off-chip precise external clock (114). One TOF output is an 11-bit digital word and a valid event trigger output indicating a valid event on the 11-bit output bus (116).
A Right qualified micro sun sensor is being developed and flight qualified for future Man missions. The micro sun sensor, which Is basically a small pinhole camera, consists of a small mask with pinholes, placed on top of an image detector. Images of the sun are formed on the image detector when the sun illuminates the mask. Image processing is performed in the sun sensor that outputs sun centroids.
High efficiency III-V multijunction solar cells deposited on metal foil or even polymer substrates can provide tremendous advantages in mass and stowage, particularly for planetary missions. As a first step towards that goal, poly-crystalline p/i/n GaAs solar cells are under development on polycrystalline Ge substrates. Organo Metallic Vapor Phase Epitaxy (OMVPE) parameters for pre-growth bake, nucleation and deposition have been examined. Single junction p/i/n GaAs photovoltaic devices, incorporating InGaP front and back window layers, have been grown and processed. Device performance has shown a dependence upon the thickness of a GaAs buffer layer deposited between the Ge substrate and the active device structure. A thick (2 m) GaAs buffer provides for both increased average device performance as well as reduced sensitivity to variations in grain size and orientation. Illumination under IR light (lambda > 1 micron), the cells showed a Voc, demonstrating the presence of an unintended photoactive junction at the GaAs/Ge interface. The presence of this junction limited the efficiency to approx.13% (estimated with an anti-refection coating) due to the current mismatch and lack of tunnel junction interconnect.
On May 11, 2009, Space Shuttle Atlantis roared off of Launch Pad 39A enroute to the Hubble Space Telescope (HST) to undertake its final servicing of HST, Servicing Mission 4. Onboard Atlantis was a small payload called the Relative Navigation Sensor experiment, which included three cameras of varying focal ranges, avionics to record images and estimate, in real time, the relative position and attitude (aka "pose") of the telescope during rendezvous and deploy. The avionics package, known as SpaceCube and developed at the Goddard Space Flight Center, performed image processing using field programmable gate arrays to accelerate this process, and in addition executed two different pose algorithms in parallel, the Goddard Natural Feature Image Recognition and the ULTOR Passive Pose and Position Engine (P3E) algorithms
A system is proposed for packaging material samples on a remote planet (especially Mars) in sealed sample tubes in preparation for later return to Earth. The sample tubes (Figure 1) would comprise (1) tubes initially having open tops and closed bottoms; (2) small, bellows-like collapsible bodies inside the tubes at their bottoms; and (3) plugs to be eventually used to close the tops of the tubes. The top inner surface of each tube would be coated with solder. The side of each plug, which would fit snugly into a tube, would feature a solder-filled ring groove. The system would include equipment for storing, manipulating, filling, and sealing the tubes. The containerization system (see Figure 2) will be organized in stations and will include: the storage station, the loading station, and the heating station. These stations can be structured in circular or linear pattern to minimize the manipulator complexity, allowing for compact design and mass efficiency. The manipulation of the sample tube between stations is done by a simple manipulator arm. The storage station contains the unloaded sample tubes and the plugs before sealing as well as the sealed sample tubes with samples after loading and sealing. The chambers at the storage station also allow for plug insertion into the sample tube. At the loading station the sample is poured or inserted into the sample tube and then the tube is topped off. At the heating station the plug is heated so the solder ring melts and seals the plug to the sample tube. The process is performed as follows: Each tube is filled or slightly overfilled with sample material and the excess sample material is wiped off the top. Then, the plug is inserted into the top section of the tube packing the sample material against the collapsible bellowslike body allowing the accommodation of the sample volume. The plug and the top of the tube are heated momentarily to melt the solder in order to seal the tube.
The Change Request (CR) assessment process is essential in the display development cycle. The assessment process is performed to ensure that the changes stated in the description of the CR match the changes in the actual display requirements. If a discrepancy is found between the CR and the requirements, the CR must be returned to the originator for corrections. Data was gathered from each of the developers to determine the type of discrepancies and the amount of time spent assessing each CR. This study sought to determine the most common types of discrepancies, and the amount of time required to assessing those issues. The study found that even though removing discrepancy before an assessment would save half the time needed to assess an CR with a discrepancy, the number of CR's found to have a discrepancy was very small compared to the total number of CR's assessed during the data gathering period.
With over 500,000 gallons of liquid hydrogen and liquid oxygen, it is of vital importance to monitor the space shuttle vehicle (SSV) from external tank (ET) load through launch. The Hazardous Gas Detection System (HGDS) was installed as the primary system responsible for monitoring fuel leaks within the orbiter and ET. The HGDS was designed to obtain the lowest possible detection limits with the best resolution while monitoring the SSV for any hydrogen, helium, oxygen, or argon as the main requirement. The HGDS is a redundant mass spectrometer used for real-time monitoring during Power Reactant Storage and Distribution (PRSD) load and ET load through launch or scrub. This system also performs SSV processing leak checks of the Tail Service Mast (TSM) umbilical quick disconnects (QD's), Ground Umbilical Carrier Plate (GUCP) QD's and supports auxiliary power unit (APU) system tests. From design to initial implementation and operations, the HGDS has evolved into a mature and reliable launch support system. This paper will discuss the operational challenges and lessons learned from facing design deficiencies, validation and maintenance efforts, life cycle issues, and evolving requirements
The Change Request (CR) assessment process is essential in the display development cycle. The assessment process is performed to ensure that the changes stated in the description of the CR match the changes in the actual display requirements. If a discrepancy is found between the CR and the requirements, the CR must be returned to the originator for corrections. Data will be gathered from each of the developers to determine the type of discrepancies and the amount of time spent assessing each CR. This study will determine the most common types of discrepancies and the amount of time spent assessing those issues. The results of the study will provide a foundation for future improvements as well as a baseline for future studies.
An algorithm denoted Gamma-SLAM performs further processing, in real time, of preprocessed digitized images acquired by a stereoscopic pair of electronic cameras aboard an off-road robotic ground vehicle to build accurate maps of the terrain and determine the location of the vehicle with respect to the maps. Part of the name of the algorithm reflects the fact that the process of building the maps and determining the location with respect to them is denoted simultaneous localization and mapping (SLAM). Most prior real-time SLAM algorithms have been limited in applicability to (1) systems equipped with scanning laser range finders as the primary sensors in (2) indoor environments (or relatively simply structured outdoor environments). The few prior vision-based SLAM algorithms have been feature-based and not suitable for real-time applications and, hence, not suitable for autonomous navigation on irregularly structured terrain. The Gamma-SLAM algorithm incorporates two key innovations: Visual odometry (in contradistinction to wheel odometry) is used to estimate the motion of the vehicle. An elevation variance map (in contradistinction to an occupancy or an elevation map) is used to represent the terrain. The Gamma-SLAM algorithm makes use of a Rao-Blackwellized particle filter (RBPF) from Bayesian estimation theory for maintaining a distribution over poses and maps. The core idea of the RBPF approach is that the SLAM problem can be factored into two parts: (1) finding the distribution over robot trajectories, and (2) finding the map conditioned on any given trajectory. The factorization involves the use of a particle filter in which each particle encodes both a possible trajectory and a map conditioned on that trajectory. The base estimate of the trajectory is derived from visual odometry, and the map conditioned on that trajectory is a Cartesian grid of elevation variances. In comparison with traditional occupancy or elevation grid maps, the grid elevation variance maps are much better for representing the structure of vegetated or rocky terrain.
This slide presentation details shuttle processing flow which starts with wheel stop and ends with launching. The flow is from landing the orbiter is rolled into the Orbiter Processing Facility (OPF), where processing is performed, it is then rolled over to the Vehicle Assembly Building (VAB) where it is mated with the propellant tanks, and payloads are installed. A different flow is detailed if the weather at Kennedy Space Center requires a landing at Dryden.
A method for multi-objective fault accommodation using predictive modeling is disclosed. The method includes using a simulated machine that simulates a faulted actual machine, and using a simulated controller that simulates an actual controller. A multi-objective optimization process is performed, based on specified control settings for the simulated controller and specified operational scenarios for the simulated machine controlled by the simulated controller, to generate a Pareto frontier-based solution space relating performance of the simulated machine to settings of the simulated controller, including adjustment to the operational scenarios to represent a fault condition of the simulated machine. Control settings of the actual controller are adjusted, represented by the simulated controller, for controlling the actual machine, represented by the simulated machine, in response to a fault condition of the actual machine, based on the Pareto frontier-based solution space, to maximize desirable operational conditions and minimize undesirable operational conditions while operating the actual machine in a region of the solution space defined by the Pareto frontier.