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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Energy Efficient Engine Low Pressure Subsystem Aerodynamic Analysis

The objective of this study was to demonstrate the capability to analyze the aerodynamic performance of the complete low pressure subsystem (LPS) of the Energy Efficient Engine (EEE). Detailed analyses were performed using three- dimensional Navier-Stokes numerical models employing advanced clustered processor computing platforms. The analysis evaluates the impact of steady aerodynamic interaction effects between the components of the LPS at design and off- design operating conditions. Mechanical coupling is provided by adjusting the rotational speed of common shaft-mounted components until a power balance is achieved. The Navier-Stokes modeling of the complete low pressure subsystem provides critical knowledge of component acro/mechanical interactions that previously were unknown to the designer until after hardware testing.

Hall, Edward J.↗
NASA NTRS1998

Energy Efficient Engine Low Pressure Subsystem Flow Analysis

The objective of this project is to provide the capability to analyze the aerodynamic performance of the complete low pressure subsystem (LPS) of the Energy Efficient Engine (EEE). The analyses were performed using three-dimensional Navier-Stokes numerical models employing advanced clustered processor computing platforms. The analysis evaluates the impact of steady aerodynamic interaction effects between the components of the LPS at design and off-design operating conditions. Mechanical coupling is provided by adjusting the rotational speed of common shaft-mounted components until a power balance is achieved. The Navier-Stokes modeling of the complete low pressure subsystem provides critical knowledge of component aero/mechanical interactions that previously were unknown to the designer until after hardware testing.

Hall, Edward J.↗
NASA NTRS1999

Entry Dispersion Analysis for the Genesis Sample Return Capsule

Genesis will be the first mission to return samples from beyond the Earth-Moon system. The spacecraft will be inserted into a halo orbit about the L1 (Sun- Earth) libration point where it will remain for two years collecting solar wind particles. Upon Earth return, the sample return capsule, which is passively controlled, will descend under parachute to Utah. The present study describes the analysis of the entry, descent, and landing scenario of the returning sample capsule. The robustness of the entry sequence is assessed through a Monte Carlo dispersion analysis where the impact of off-nominal conditions is ascertained. The dispersion results indicate that the capsule attitude excursions near peak heating and drogue chute deployment are within Genesis mission limits. Additionally, the size of the resulting 3-sigma landing ellipse is 47.8 km in downrange by 15.2 km in crossrange, which is within the Utah Test and Training Range boundaries.

Desai, Prasun N.↗
NASA NTRS1999

Entry Dispersion Analysis for the Genesis Sample Return Capsule

Genesis will be the first mission to return samples from beyond the Earth-Moon system. The spacecraft will be inserted into a halo orbit about the L1 (Sun- Earth) libration point where it will remain for two years collecting solar wind particles. Upon Earth return, the sample return capsule, which is passively controlled, will descend under parachute to Utah. The present study describes the analysis of the entry, descent, and landing scenario of the returning sample cap- sule. The robustness of the entry sequence is assessed through a Monte Carlo dispersion analysis where the impact of off-nominal conditions is ascertained. The dispersion results indicate that the capsule attitude excursions near peak heating and drogue chute deployment are within Genesis mission limits. Additionally, the size of the resulting 3-sigma landing ellipse is 47.8 km in downrange by 15.2 km in crossrange, which is within the Utah Test and Training Range boundaries.

Desai, Prasun, N.↗
NASA NTRS2000

Commercial Off-The-Shelf (COTS) Program: Issues and Results of Upscreening COTS Parts for NASA Flight Hardware

This paper presents The Commercial Off-The-Shelf Program (COTS). The topics of discussion are: 1) Introduction of COTS; 2) MARS01 Program/Requirements; 3) MARS01 COTS Screening Flow; 4) Test Results-Electrical, C-Sam, Burn-In; 5) Value Added Analysis (Risk Reduction); 6) Value Added Analysis (Cost); 7) Impact of COTS ++ Screening; and 8) Summary. This paper is presented in viewgraph form.

Sandor, Mike↗
NASA NTRS1999

Electronic Packaging for Space Applications Workshop 1999

This paper presents viewgraphs on the Commercial Off-The-Shelf (COTS) Program. The topics include: 1) Advocacy for COTS; 2) MARS01 Program/Requirements; 3) MARS01 COTS Screening Flow; 4) Test Results-Electrical, C-Sam, Burn-In; 5) Value Added Analysis (Risk Reduction); 6) Value Added Analysis (Cost); 7) Impact of COTS ++ Screening and 8) Summary.

Sandor, Mike↗
NASA NTRS2000

New Views of the Moon: Improved Understanding Through Data Integration

Understanding the Moon is crucial to future exploration of the solar system.The Moon preserves a record of the first billion years of the Earth-Moon system's history, including evidence of the Moon's origin as accumulated debris from a giant impact into early Earth. Lunar rocks provide evidence of early differentiation and extraction of a crust. Lacking an atmospheric shield, the Moon's regolith retains a record of the activity of solar wind over the past 4 billion years. It also holds a complete record of impact cratering, and analysis of samples has allowed calibration of ages, and thus dating of other planetary surfaces. And because of its proximity to Earth, it's low gravity well, and stable surface, the Moon's resources will be useful both in establishing lunar habitations and as fuel for exploration beyond the Moon. Lunar science has advanced tremendously in the 30 years since the Apollo and Luna missions. We know that the Moon is strongly differentiated, and recent tungsten isotope studies indicate that this differentiation occurred soon after solar system formation. The Moon probably accreted rapidly from debris that formed as a large planetesimal struck the early Earth. Ancient highland rocks provide evidence of early lunar differentiation, and basalts formed by later melting within the mantle reveal it cumulus nature. However, the timing, extent, and depth of differentiation, variations within the mantle, and lateral and vertical variations within the crust can only be surmised from the limited sample suites,gravity studies,and surface geophysics of the Apollo era. Data from the recent Lunar Prospector and Clementine missions permit reassessment of the global characteristics of the Moon and a reexamination of the distribution of elemental components, rock and soil types, and resources, as well as remanent magnetism, gravity field, and global topography New research provides some answers, but also leads to new questions.

Jolliff, B. L.↗
NASA NTRS1995

Why the SL9 Plumes Were All About the Same Height

Several of the SL9 ejecta plumes were observed by the HST to reach approximately the same height, about 3000 km above the jovian cloud tops. The duration of the infrared events, which were produced by the plume falling back on the atmosphere, measures time aloft and hence provides a second, more sensitive measure of plume height; the light curves indicate that the largest impacts produced modestly higher plumes. Evidently these plumes were launched with about the same vertical velocity, roughly 10-13 kilometers per second. As the impactors themselves were not all the same, nor the impacts equally luminous, nor the plumes equally opaque, the similar plume heights has been seen as a puzzle needing explanation. A second, closely related matter that needs to addressed quantitatively is the popular contention that a big plume requires a big impact. This view is misleading at best, yet plume heights can be used to constrain impact parameters. Dimensional analysis indicates that plume height goes as z alpha v (sup 2) (sub ej) alpha E/pH (sup 2), where v (sub ej) is the ejection velocity, E the explosion energy, and p and H the ambient pressure and scale height at termination. Using a semi-analytic model for the deceleration, disintegration, and destruction of intruding bodies by an ever-vigilant atmosphere, we find that the ratio E/pH(sup 2) is roughly constant for fragments with diameters of order 100 m to 1000 m. Constancy of v(sub ej) is in part due to the greater role of radiative ablation on the flight of smaller objects. We conclude that similar plume heights is a direct consequence of smaller impactors exploding at higher altitudes, in such a way that the different explosions were geometrically similar.

Zahnle, K.↗
NASA NTRS2004

The Case for Deep Space Telecommunications Relay Stations

Each future mission to Jupiter and beyond must carry the traditional suite of telecommunications systems for command and control and for mission data transmission to earth. The telecommunications hardware includes the large antenna and the high-power transmitters that enable the communications link. Yet future spacecraft will be scaled down from the hallmark missions of Galileo and Cassini to Jupiter and Saturn, respectively. This implies that a higher percentage of the spacecraft weight and power must be dedicated to telecommunications system. The following analysis quantifies this impact to future missions and then explores the merits of an alternative approach using deep space relay stations for the link back to earth. It will be demonstrated that a telecommunications relay satellite would reduce S/C telecommunications weight and power sufficiently to add one to two more instruments.

Chandler, Charles W.↗
NASA NTRS2004

Radiation Assurance for the Space Environment

The space radiation environment can lead to extremely harsh operating conditions for spacecraft electronic systems. A hardness assurance methodology must be followed to assure that the space radiation environment does not compromise the functionality and performance of space-based systems during the mission lifetime. The methodology includes a definition of the radiation environment, assessment of the radiation sensitivity of parts, worst-case analysis of the impact of radiation effects, and part acceptance decisions which are likely to include mitigation measures.

Barth, Janet L.↗
NASA NTRS2005

Entry Dispersion Analysis for the Genesis Sample Return Capsule

Genesis will be the first mission to return samples from beyond the Earth-Moon system. The spacecraft will be inserted into a halo orbit about the L1 (Sun-Earth) libration point where it will remain for two years collecting solar wind particles. Upon Earth return, the sample return capsule, which is passively controlled, will descend under parachute to Utah. The present study describes the analysis of the entry, descent, and landing scenario of the returning sample capsule. The robustness of the entry sequence is assessed through a Monte Carlo dispersion analysis where the impact of off-nominal conditions is ascertained. The dispersion results indicate that the capsule attitude excursions near peak heating and drogue chute deployment are within Genesis mission limits. Additionally, the size of the resulting 3-sigma landing ellipse is 47.8 km in downrange by 15.2 km in crossrange, which is within the Utah Test and Training Range boundaries.

Desai, Prasun N.↗
NASA NTRS2003

Evidence for Tropopause Layer Moistening by Convection During CRYSTAL-FACE

Measurements and analysis of the impact of deep convection on tropopause layer moisture are easily confounded by difficulties making precise observations with sufficient spatial coverage before and after convective events and difficulties distinguishing between changes due to local convection versus large-scale advection. The interactions between cloud microphysics and dynamics in the convective transport of moisture into the tropopause layer also result in a sufficiently complex and poorly characterized system to allow for considerable freedom in theoretical models of stratosphere-troposphere exchange. In this work we perform detailed large-eddy simulations with an explicit cloud microphysics model to study the impact of deep convection on tropopause layer moisture profiles observed over southern Florida during CRYSTALFACE. For four days during the campaign (July 11, 16, 28, and 29) we initialize a 100-km square domain with temperature and moisture profiles measured prior to convection at the PARSL ground site, and initiate convection with a warm bubble that produces an anvil at peak elevations in agreement with lidar and radar observations on that day. Comparing the moisture field after the anvils decay with the initial state, we find that convection predominantly moistens the tropopause layer (as defined by minimum temperature and minimum potential temperature lapse rate), although some drying is also predicted in localized layers. We will also present results of sensitivity tests designed to separate the roles of cloud microphysics and dynamics.

Ackerman, A.↗
NASA NTRS2010

Use of Traditional and Novel Methods to Evaluate the Influence of an EVA Glove on Hand Performance

The gloved hand is one of an astronaut s primary means of interacting with the environment, and any restrictions imposed by the glove can strongly affect performance during extravehicular activity (EVA). Glove restrictions have been the subject of study for decades, yet previous studies have generally been unsuccessful in quantifying glove mobility and tactility. Past studies have tended to focus on the dexterity, strength, and functional performance of the gloved hand; this provides only a circumspect analysis of the impact of each type of restriction on the glove s overall capability. The aim of this study was to develop novel capabilities to provide metrics for mobility and tactility that can be used to assess the performance of a glove in a way that could enable designers and engineers to improve their current designs. A series of evaluations were performed to compare unpressurized and pressurized (4.3 psi) gloved conditions with the ungloved condition. A second series of evaluations were performed with the Thermal Micrometeoroid Garment (TMG) removed. This series of tests provided interesting insight into how much of an effect the TMG has on gloved mobility - in some cases, the presence of the TMG restricted glove mobility as much as pressurization did. Previous hypotheses had assumed that the TMG would have a much lower impact on mobility, but these results suggest that an improvement in the design of the TMG could have a significant impact on glove performance. Tactility testing illustrated the effect of glove pressurization, provided insight into the design of hardware that interfaces with the glove, and highlighted areas of concern. The metrics developed in this study served to benchmark the Phase VI EVA glove and to develop requirements for the next-generation glove for the Constellation program.

Benson, Elizabeth A.↗
NASA NTRS2010

Influence of Satellite-Based Heterogeneous Vegetation Momentum Roughness on Mesoscale Model Dynamics During IHOP 2002

The sensitivity of mesoscale weather prediction model to a vegetation roughness initialization is investigated for the south central United States. Three different roughness databases are employed: i) a control or standard lookup table roughness that is a function only of land cover type, ii) a spatially heterogeneous roughness database previously derived using a physically based procedure and MODIS imagery, and iii) a MODIS climatologic roughness database that possesses the same spatial heterogeneity as (i) but with mean land class values from (ii). The model used is the Weather Research and Forecast Model (WRF) coupled to the Community Land Model within the Land Information System (LIS). For each simulation, a statistical comparison is made between modeled results and ground observations from meteorological stations within the Oklahoma mesonet and surrounding region during IHOP20O2. A sensitivity analysis on the impact the MODIS-based roughness fields is also made through a time-series intercomparison of temperature bias, probability of detection (POD), average wind speed, boundary layer height, and turbulent kinetic energy (TKE) the results that, for the current replacement of the standard land-cover type based roughness values with the satellite-derived fields statistically improves model performance for most of the observed variables. Further, the satellite-based roughness enhances the surface wind speed, PBL height and TKE production on the order of 3 to l0 percent, with a lesser effect over grassland and cropland domains, and the greater effect over mixed land cover domains

Jasinski, Michael↗
NASA NTRS2010

Optimizing Air Transportation Service to Metroplex Airports: Analysis Using the Airline Schedule Optimization Model (ASOM) - Par 2

The air transportation system is a significant driver of the U.S. economy, providing safe, affordable, and rapid transportation. During the past three decades airspace and airport capacity has not grown in step with demand for air transportation; the failure to increase capacity at the same rate as the growth in demand results in unreliable service and systemic delay. This report describes the results of an analysis of airline strategic decision-making that affects geographic access, economic access, and airline finances, extending the analysis of these factors using historic data (from Part 1 of the report). The Airline Schedule Optimization Model (ASOM) was used to evaluate how exogenous factors (passenger demand, airline operating costs, and airport capacity limits) affect geographic access (markets-served, scheduled flights, aircraft size), economic access (airfares), airline finances (profit), and air transportation efficiency (aircraft size). This analysis captures the impact of the implementation of airport capacity limits, as well as the effect of increased hedged fuel prices, which serve as a proxy for increased costs per flight that might occur if auctions or congestion pricing are imposed; also incorporated are demand elasticity curves based on historical data that provide information about how passenger demand is affected by airfare changes.

Donoue, George↗
NASA NTRS2011

Numerical Model Sensitivity to Heterogeneous Satellite Derived Vegetation Roughness

The sensitivity of a mesoscale weather prediction model to a 1 km satellite-based vegetation roughness initialization is investigated for a domain within the south central United States. Three different roughness databases are employed: i) a control or standard lookup table roughness that is a function only of land cover type, ii) a spatially heterogeneous roughness database, specific to the domain, that was previously derived using a physically based procedure and Moderate Resolution Imaging Spectroradiometer (MODIS) imagery, and iii) a MODIS climatologic roughness database that like (i) is a function only of land cover type, but possesses domain specific mean values from (ii). The model used is the Weather Research and Forecast Model (WRF) coupled to the Community Land Model within the Land Information System (LIS). For each simulation, a statistical comparison is made between modeled results and ground observations within a domain including Oklahoma, Eastern Arkansas, and Northwest Louisiana during a 4-day period within IHOP 2002. Sensitivity analysis compares the impact the three roughness initializations on time-series temperature, precipitation probability of detection (POD), average wind speed, boundary layer height, and turbulent kinetic energy (TKE). Overall, the results indicate that, for the current investigation, replacement of the standard look-up table values with the satellite-derived values statistically improves model performance for most observed variables. Such natural roughness heterogeneity enhances the surface wind speed, PBL height and TKE production up to 10 percent, with a lesser effect over grassland, and greater effect over mixed land cover domains.

Jasinski, Michael↗
NASA NTRS2011

Coupled Fluids-Radiation Analysis of a High-Mass Mars Entry Vehicle

The NEQAIR line-by-line radiation code has been incorporated into the DPLR Navier-Stokes flow solver such that the NEQAIR subroutines are now callable functions of DPLR. The coupled DPLR-NEQAIR code was applied to compute the convective and radiative heating rates over high-mass Mars entry vehicles. Two vehicle geometries were considered - a 15 m diameter 70-degree sphere cone configuration and a slender, mid-L/D vehicle with a diameter of 5 m called an Ellipsled. The entry masses ranged from 100 to 165 metric tons. Solutions were generated for entry velocities ranging from 6.5 to 9.1 km/s. The coupled fluids-radiation solutions were performed at the peak heating location along trajectories generated by the Traj trajectory analysis code. The impact of fluids-radiation coupling is a function of the level of radiative heating and the freestream density and velocity. For the high-mass Mars vehicles examined in this study, coupling effects were greatest for entry velocities above 8.5 km/s where the surface radiative heating was reduced by up 17%. Generally speaking, the Ellipsled geometry experiences a lower peak radiative heating rate but a higher peak turbulent convective heating rate than the MSL-based vehicle.

Palmer, Grant↗
NASA NTRS2012

TRMM Version 7 Level 3 Gridded Monthly Accumulations of GPROF Precipitation Retrievals

In July 2011, improved versions of the retrieval algorithms were approved for TRMM. All data starting with June 2011 are produced only with the version 7 code. At the same time, version 7 reprocessing of all TRMM mission data was started. By the end of August 2011, the 14+ years of the reprocessed mission data became available online to users. This reprocessing provided the opportunity to redo and enhance upon an analysis of V7 impacts on L3 data accumulations that was presented at the 2010 EGU General Assembly. This paper will discuss the impact of algorithm changes made in th GPROF retrieval on the Level 2 swath products. Perhaps the most important change in that retrieval was to replacement of a model based a priori database with one created from Precipitation Radar (PR) and TMI brightness temperature (Tb) data. The radar pays a major role in the V7 GPROF (GPROF2010) in determining existence of rain. The level 2 retrieval algorithm also introduced a field providing the probability of rain. This combined use of the PR has some impact on the retrievals and created areas, particularly over ocean, where many areas of low-probability precipitation are retrieved whereas in version 6, these areas contained zero rain rates. This paper will discuss how these impacts get translated to the space/time averaged monthly products that use the GPROF retrievals. The level 3 products discussed are the gridded text product 3G68 and the standard 3A12 and 3B31 products. The paper provides an overview of the changes and explanation of how the level 3 products dealt with the change in the retrieval approach. Using the .25 deg x .25 degree grid, the paper will show that agreement between the swath product and the level 3 remains very high. It will also present comparisons of V6 and V7 GPROF retrievals as seen both at the swath level and the level 3 time/space gridded accumulations. It will show that the various L3 products based on GPROF level 2 retrievals are in close agreement. The paper concludes by outlining some of the challenges of the TRMM version 7 level 3 products.

Stocker, E. F.↗