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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.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Spatial, Temporal, and Electrical Characteristics of Lightning in Reported Lightning-Initiated Wildfire Events

Analysis was performed to determine whether a lightning flash could be associated with every reported lightning-initiated wildfire that grew to at least 4 km(exp 2). In total, 905 lightning-initiated wildfires within the Continental United States (CONUS) between 2012 and 2015 were analyzed. Fixed and fire radius search methods showed that 81–88% of wildfires had a corresponding lightning flash within a 14 day period prior to the report date. The two methods showed that 52–60% of lightning-initiated wildfires were reported on the same day as the closest lightning flash. The fire radius method indicated the most promising spatial results, where the median distance between the closest lightning and the wildfire start location was 0.83 km, followed by a 75th percentile of 1.6 km and a 95th percentile of 5.86 km. Ninety percent of the closest lightning flashes to wildfires were negative polarity. Maximum flash densities were less than 0.41 flashes km(exp 2) for the 24 h period at the fire start location. The majority of lightning-initiated holdover events were observed in the Western CONUS, with a peak density in north-central Idaho. A twelve day holdover event in New Mexico was also discussed, outlining the opportunities and limitations of using lightning data to characterize wildfires.

Flash density↗
NASA NTRS2004

Materials Processing in Space: Model Experiments aboard the International Space Station

Direct observation of fluid flow, bubble movement and solidification during controlled melting and solidification of succinonitrile were conducted in the glovebox facility of the International Space Station (ISS). The samples were processed in the Pore Formation and Mobility Investigation (PFMI) apparatus in the glovebox facility (GBX) on board the ISS. Experimental processing parameters of temperature gradient and translation speed, as well as camera settings, were remotely monitored and manipulated from the ground Telescience Center (TSC) at the Marshall Space Flight Center. Real time visualization of the controlled directional melt back and resolidification reveals a number of microgravity dependent phenomena otherwise masked by Earth s gravity. These and some initial analysis of the observed events is presented.

Grugel, Richard↗
NASA NTRS2016

Plasma Observations During the Mars Atmospheric Plume Event of March-April 2012

We present initial analysis and conclusions from plasma observations made during the reported Mars Dust plume event of March - April 2012. During this period, multiple independent amateur observers detected a localized, high-altitude plume over the Martian dawn terminator [Sanchez-Lavega7 et al., Nature, 2015, doi:10.1038nature14162], the origin of which remains to be explained. We report on in-situ measurements of ionospheric plasma density and solar wind parameters throughout this interval made by Mars Express, obtained over the surface region, but at the opposing terminator. We tentatively conclude that the formation and/or transport of this plume to the altitudes where it was observed could be due in part the result of a large interplanetary coronal mass ejection (ICME) encountering the Martian system. Interestingly, we note that a similar plume detection in May 1997 may also have been associated with a large ICME impact at Mars.

Plumes↗
NASA NTRS1998

Vertical and Horizontal Wind Structure Prior to and During the 1997/1998 ENSO Event

Analyses of ECMWF and satellite wind products are used to investigate low frequency fluctuations in the wind fields immediately preceding and during the 1997/1998 ENSO event. An extended EOF analysis of the horizontal and vertical wind structure that allows for the study of propagating features indicates that the dominant mode of variability established in the lower levels of the atmosphere is a convergence in the central tropical Pacific. At mid-levels, the westerlies increase with time over most of the equatorial Pacific, and there are closed cyclonic features on either side of the equator. At upper levels, the flow tends to become divergent across the equatorial Pacific, and there is a strong flow from the northwest Pacific across Indonesia that then turns to the west along the equator in the Indian Ocean. The addition of satellite data for improved surface wind estimates reveal that the Indian Ocean winds were anomalously strong during the winter preceding the initiation of the ENSO event. An analysis of the momentum convergence flux at the surface indicates a very strong anomaly 9 months prior to the ENSO event that begins in the western Indian Ocean and propagates to the east, arriving over the Pacific warm pool area coincident with the beginning of the El Nino. Changes in the near surface thermal and water vapor structure over the Indian Ocean during this period will also be discussed.

Adamec, David↗
NASA NTRS2010

The Impact of Ocean Data Assimilation on Seasonal-to-Interannual Forecasts: A Case Study of the 2006 El Nino Event

This study investigates the impact of four different ocean analyses on coupled forecasts of the 2006 El Nino event. Forecasts initialized in June 2006 using ocean analyses from an assimilation that uses flow-dependent background error covariances are compared with those using static error covariances that are not flow dependent. The flow-dependent error covariances reflect the error structures related to the background ENSO instability and are generated by the coupled breeding method. The ocean analyses used in this study result from the assimilation of temperature and salinity, with the salinity data available from Argo floats. Of the analyses, the one using information from the coupled bred vectors (BV) replicates the observed equatorial long wave propagation best and exhibits more warming features leading to the 2006 El Nino event. The forecasts initialized from the BV-based analysis agree best with the observations in terms of the growth of the warm anomaly through two warming phases. This better performance is related to the impact of the salinity analysis on the state evolution in the equatorial thermocline. The early warming is traced back to salinity differences in the upper ocean of the equatorial central Pacific, while the second warming, corresponding to the mature phase, is associated with the effect of the salinity assimilation on the depth of the thermocline in the western equatorial Pacific. The series of forecast experiments conducted here show that the structure of the salinity in the initial conditions is important to the forecasts of the extension of the warm pool and the evolution of the 2006 El Ni o event.

Yang, Shu-Chih↗
NASA NTRS2010

3D GeoWall Analysis System for Shuttle External Tank Foreign Object Debris Events

An analytical, advanced imaging method has been developed for the initial monitoring and identification of foam debris and similar anomalies that occur post-launch in reference to the space shuttle s external tank (ET). Remote sensing technologies have been used to perform image enhancement and analysis on high-resolution, true-color images collected with the DCS 760 Kodak digital camera located in the right umbilical well of the space shuttle. Improvements to the camera, using filters, have added sharpness/definition to the image sets; however, image review/analysis of the ET has been limited by the fact that the images acquired by umbilical cameras during launch are two-dimensional, and are usually nonreferenceable between frames due to rotation translation of the ET as it falls away from the space shuttle. Use of stereo pairs of these images can enable strong visual indicators that can immediately portray depth perception of damaged areas or movement of fragments between frames is not perceivable in two-dimensional images. A stereoscopic image visualization system has been developed to allow 3D depth perception of stereo-aligned image pairs taken from in-flight umbilical and handheld digital shuttle cameras. This new system has been developed to augment and optimize existing 2D monitoring capabilities. Using this system, candidate sequential image pairs are identified for transformation into stereo viewing pairs. Image orientation is corrected using control points (similar points) between frames to place the two images in proper X-Y viewing perspective. The images are then imported into the WallView stereo viewing software package. The collected control points are used to generate a transformation equation that is used to re-project one image and effectively co-register it to the other image. The co-registered, oriented image pairs are imported into a WallView image set and are used as a 3D stereo analysis slide show. Multiple sequential image pairs can be used to allow forensic review of temporal phenomena between pairs. The observer, while wearing linear polarized glasses, is able to review image pairs in passive 3D stereo.

Brown, Richard↗
NASA NTRS1995

Single Event Upset Effects on the Clementine Solid State Data Recorder

The sensitivity of the Clementine 2.1 Gbit Solid State Data Recorder (SSDR) to single event upsets was characterized in ground tests. Subsequent in-situ measurements of the ambient radiation environment by experiments on-board Clementine permitted evaluation of the ability of models of the single event phenomenon in the SSDR to be tested using actual data. Initial results from the analysis reveal a nearly constant background upset rate of ~71 bit flips/day for the SSDR. There is no obvious correlation with a solar proton event recorded by Clementine and several other spacecraft on 20-21 February 1994, indicating that the SSDR was not sensitive to protons. The constant rate is thus interpreted as being a function of the Galactic Cosmic Ray heavy ion environment. A pronounced lunar orbit altitude dependence has also been identified in the data though the cause has not yet been unambiguously identified.

Clementine↗
NASA NTRS1995

Galileo NIMS Direct Observations of the SL-9 Fireballs

The Galileo spacecraft was situated 1.8 AU from Jupiter, at a phase angle of 51 deg, providing a direct view of the impacts of the comet fragments with the planet. Low resolution infrared spectra in the 1 to 5 micron range were recorded for several of the events, which can be used to study the early evolution of the fireballs. Preliminary analysis of the data received for the G event show an initial fireball temperature of greater than 5000 K and an effective source diameter of less than 10 km. These spectra show absorption by molecular hydrogen and methane which place the upper emitting surface in the stratosphere, above the ammonia cloud level. As time progresses, the fireball cools and the effective diameter of the radiating area increases at roughly 2 km/sec. In 30 seconds, the fireball cools to approximately 1000 k and exhibits a diameter of about 100 km.

NIMS↗
NASA NTRSDate not supplied

Robust Trajectory Optimization Techniques Using a Sweeping Gradient Method and Linear Covariance Analysis

We present robust trajectory optimization techniques using a sweeping gradient method for ordinary differential equations with events (SGM) and linear covariance analysis (LinCov). SGM is a method for computing the gradient of trajectory analyses defined by performance indices over initial value problems with events with respect to static parameters. LinCov is an analytic technique for predicting stochastic behavior of dynamical systems. By combining SGM and LinCov, it is possible use efficient, off-the-shelf, gradient-based optimizers to solve robust optimal trajectory design problems. We describe the individual methods and some details on how they can be combined. Then we apply the combined techniques to a variety of orbital trajectory design problems to demonstrate its use, including minimum fuel transfer and mid-course correction burn scheduling.

Benjamin W L Margolis↗
NASA NTRS2009

An Operational Assessment of the MODIS False Color Composite with the Great Falls, Montana National Weather Service

The close and productive collaborations between the NWS Warning and Forecast Office (WFO) in Great Falls, MT and the Short Term Prediction and Research Transition (SPORT) Center at NASA/Marshall Space Flight Center have provided a unique opportunity for science sharing and technology transfer. In particular, SPoRT has provided a false color composite product derived from MODIS data, which is part of NASA's Earth Observing System. This product is designed to delineate snow and ice covered ground, bare ground and clouds. The Great Falls WFO has been a test bed of the MODIS false color composite as a tool in operations to monitor the development and dissipation of snow cover In particular, preliminary applications have shown that the product can be used to monitor snow cover in remote locations as well as ice in rivers. This information can lead to improved assessments of flooding potential during post event conditions where rapid melting and runoff are anticipated. The potential of this product on future geostationary satellites may substantially contribute to the NWS mission by providing enhanced situational awareness. The operational use of this product has been transitioned at WFO Great Falls through a process of product implementation, discussions with the service hydrologist and forecasters, and post event analysis. A concentrated assessment period from January to March, 2008 was initiated to investigate the impact of the MODIS false color product on WFO Great Falls' operations. This presentation will emphasize the impact the MODIS false color product had in the WFO's situational awareness and how best this information can be used to influence operational decisions.

Loss, GIna↗
NASA NTRS1983

The System View

Analysis of spacecraft to ground communications link performance and a description of the Deep Space Network system is provided. Due to the tremendous distances involved in communicating between the spacecraft at the edge of our solar system and Earth, communications link performance is stretched to the limit of theoretical predictions. This is required in order to return the maximum amount of data possible during critical events such as planetary flybys. The link analysis provides a basis for the initial link design before spacecraft launch and performance prediction and monitoring during spacecraft flight. Additionally, it indicates what performance upgrades are required for mission extensions and new missions. Performance is improved through the use of a larger antenna collecting area, greater transmitter power, lower receiving system noise temperature and more sophisticated data coding schemes. The performance of the Deep Space Station configuration which serves as the ground portion of the communications link is assessed.

Noreen, G. K.↗
NASA NTRS2017

And the Humans Save the Day or Maybe They Ruin It: The Importance of Humans in the Loop

Flying a mission in space requires a massive commitment of resources, and without the talent and commitment of the people involved in this effort we would never leave the atmosphere of Earth. When we use the phrase "humans in the loop", it could apply to almost any endeavor since everything starts with humans developing a concept, completing the design process, building or implementing a product and using the product to achieve a goal or purpose. Narrowing the focus to spaceflights, there are a variety of individuals involved throughout the preparations for flight and the flight itself. All of the humans involved add value and support for program success. The purpose of this paper focuses on how a Probabilistic Risk Assessment (PRA) accounts for the human in the loop for potential missions using a technique called Human Reliability Analysis (HRA). Human actions can increase or decrease the overall risk via initiating events or mitigating them, thus removing the human from the loop doesn't always lower the risk.

DeMott, Diana↗
NASA NTRS2012

MSL DSENDS EDL Analysis and Operations

This paper presents the operations experience of the JPL EDL (Entry, Descent, and Landing) trajectory simulation team, focusing on events in the week before landing and EDL itself. A brief description of the EDL trajectory simulation tool used for targeting and simulation verification analysis will be presented, including a high level discussion of the required modeling. Initialization and output interfaces used for landing hazard analysis will also be covered, along with discussion of real-time EDL event detection using radiometric Doppler data.

Entry, descent, and landing (EDL)↗
NASA NTRS2001

Different mechanisms of radiation-induced loss of heterozygosity in two human lymphoid cell lines from a single donor

Allelic loss is an important mutational mechanism in human carcinogenesis. Loss of heterozygosity (LOH) at an autosomal locus is one outcome of the repair of DNA double-strand breaks (DSBs) and can occur by deletion or by mitotic recombination. We report that mitotic recombination between homologous chromosomes occurred in human lymphoid cells exposed to densely ionizing radiation. We used cells derived from the same donor that express either normal TP53 (TK6 cells) or homozygous mutant TP53 (WTK1 cells) to assess the influence of TP53 on radiation-induced mutagenesis. Expression of mutant TP53 (Met 237 Ile) was associated with a small increase in mutation frequencies at the hemizygous HPRT (hypoxanthine phosphoribosyl transferase) locus, but the mutation spectra were unaffected at this locus. In contrast, WTK1 cells (mutant TP53) were 30-fold more susceptible than TK6 cells (wild-type TP53) to radiation-induced mutagenesis at the TK1 (thymidine kinase) locus. Gene dosage analysis combined with microsatellite marker analysis showed that the increase in TK1 mutagenesis in WTK1 cells could be attributed, in part, to mitotic recombination. The microsatellite marker analysis over a 64-cM region on chromosome 17q indicated that the recombinational events could initiate at different positions between the TK1 locus and the centromere. Virtually all of the recombinational LOH events extended beyond the TK1 locus to the most telomeric marker. In general, longer LOH tracts were observed in mutants from WTK1 cells than in mutants from TK6 cells. Taken together, the results demonstrate that the incidence of radi-ation-induced mutations is dependent on the genetic background of the cell at risk, on the locus examined, and on the mechanisms for mutation available at the locus of interest.

NASA Discipline Radiation Health↗
NASA NTRS2006

Central East Pacific Flight Routing

With the introduction of the Federal Aviation Administration s Advanced Technology and Oceanic Procedures system at the Oakland Oceanic Center, a level of automation now exists in the oceanic environment to potentially begin accommodating increased user preferred routing requests. This paper presents the results of an initial feasibility assessment which examines the potential benefits of transitioning from the fixed Central East Pacific routes to user preferred routes. As a surrogate for the actual user-provided routing requests, a minimum-travel-time, wind-optimal dynamic programming algorithm was developed and utilized in this paper. After first describing the characteristics (e.g., origin airport, destination airport, vertical distribution and temporal distribution) of the westbound flights utilizing the Central East Pacific routes on Dec. 14-16 and 19-20, the results of both a flight-plan-based simulation and a wind-optimal-based simulation are presented. Whereas the lateral and longitudinal distribution of the aircraft trajectories in these two simulations varied dramatically, the number of simulated first-loss-of-separation events remained relatively constant. One area of concern that was uncovered in this initial analysis was a potential workload issue associated with the redistribution of traffic in the oceanic sectors due to thc prevailing wind patterns.

Grabbe, Shon↗
NASA NTRS1999

COMPTEL Studies of Gamma-Ray Bursts at MeV Energies

The purpose of this program was to analyse and interpret gamma-ray burst (GRB) data using both telescope mode data and single detector burst mode data from COMPTEL. Collectively, these data span the energy range from 300 keV up to 30 MeV. The initial goal of our proposal was to perform a standard analysis for each significant GRB event seen by COMPTEL. This includes GRBs that are registered by the telescope mode data as well as GRBs that are registered only in the burst mode data. (The latter category includes both GRBs that he outside of the FoV as well as GRBs within the FoV that are too weak to be seen in the telescope mode.) A second goal of our proposal was to define a set of data products (including deconvolved photon spectra) that, for each detected GRB event, would be made available via the COMPTEL GRB Web Page. The third goal of our program was to perform more detailed studies of selected GRB events. This represented a continuation of past GRB studies by the COMPTEL team. In general, we have met with only limited success in achieving these goals, in part due to the limited resources provided and our philosophy of utilizing local high school students to participate in this effort. Using local high school student support, however, we expect that considerable progress will be made in our efforts to catalog the COMPTEL gamma-ray burst data between now and the end of the current academic year. In addition, observations with COMPTEL contributed to an analysis of GRB 990123, the first gamma-ray burst with simultaneous optical observations.

McConnell, Mark L.↗
NASA NTRS2000

Thermoelastic Analysis of Hyper-X Camera Windows Suddenly Exposed to Mach 7 Stagnation Aerothermal Shock

To visually record the initial free flight event of the Hyper-X research flight vehicle immediately after separation from the Pegasus(registered) booster rocket, a video camera was mounted on the bulkhead of the adapter through which Hyper-X rides on Pegasus. The video camera was shielded by a protecting camera window made of heat-resistant quartz material. When Hyper-X separates from Pegasus, this camera window will be suddenly exposed to Mach 7 stagnation thermal shock and dynamic pressure loading (aerothermal loading). To examine the structural integrity, thermoelastic analysis was performed, and the stress distributions in the camera windows were calculated. The critical stress point where the tensile stress reaches a maximum value for each camera window was identified, and the maximum tensile stress level at that critical point was found to be considerably lower than the tensile failure stress of the camera window material.

Ko, William L.↗
NASA NTRS2003

A Systematic Global Mapping of the Radiation Field at Aviation Altitudes

This paper presents early results from aircraft measurements made by a Low-LET Radiation Spectrometer (LoLRS), as part of a long-range effort to study the complex dynamics of the atmospheric radiation field. For this purpose, a comprehensive data base is being generated to enable a multivariable global mapping (and eventually modeling) of doses and Linear-Energy-Transfer (LET) spectra at aviation altitudes. To accomplish this, a methodical collection of data from the LoLRS (and other instruments), is planned over extended periods of time, in a manner that complements some previous isolated and sporadic measurements by other workers, with the objective to generate a detailed long-range description of the cosmic-ray induced particle environment and to study its variability and dependence on atmospheric thickness, magnetic latitude, L-shell or rigidity, space weather, solar particle events, solar cycle effects, magnetic field variation, diurnal and seasonal effects, and atmospheric weather. Analysis of initial data indicates that the dose is rising with increasing altitude and increasing magnetic latitude. Comparison of total doses with predictions is in good agreement.

Stassinopoulos, E. G.↗