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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 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Aeroacoustic Analysis using Dynamic Mode Decomposition of Unsteady Pressure-Sensitive Paint Measurements

In this paper, we present a new method for the diagnosis and analysis of aeroacoustic phenomena. Taking advantage of the well-known property that the measurements of the Unsteady Pressure-Sensitive Paint (uPSP) have much higher spatial resolution compared to those of the conventional pressure transducers, the method is based on the visualization and analysis of the outputs of the Dynamic Mode Decomposition (DMD) of the uPSP measurements. The uPSP measurements were collected with four Phantom high-speed cameras in the Ascent Transient Aerodynamics Test (ATAT) of the Space Launch System (SLS) Block 1 cargo vehicle in the 11-by-11-foot transonic test section of the Unitary Plan Wind Tunnel (UPWT) at NASA Ames Research Center in September 2019. The method presented in this paper is demonstrated by investigating an interesting phenomenon observed in the SLS ATAT – the vortex shedding tone generated by the forward attachment of the Solid Rocket Booster (SRB). As examples, the DMD outputs of the uPSP measurements in a subsonic test in the SLS ATAT are presented. It is shown the information retrieved from the DMD outputs of the uPSP measurements can be effectively used in the identification and diagnosis of the aeroacoustic phenomena. The work described in this paper is a part of NASA’s development of a new state-of-the-art uPSP capability in production wind tunnels. Funding was provided by the NASA Aerosciences Evaluation and Test Capabilities Portfolio Office.

acoustics↗
NASA NTRS2014

SLS Trade Study 0058: Day of Launch (DOL) Wind Biasing

SLS heritage hardware and legacy designs have shown load exceedances at several locations during Design Analysis Cycles (DAC): MPCV Z bending moments; ICPS Electro-Mechanical Actuator (EMA) loads; Core Stage loads just downstream of Booster forward interface. SLS Buffet Loads Mitigation Task Team (BLMTT) tasked to study issue. Identified low frequency buffet load responses are a function of the vehicle's total angle of attack (AlphaTotal). SLS DOL Wind Biasing Trade team to analyze DOL wind biasing methods to limit maximum AlphaTotal in the M0.8 - 2.0 altitude region for EM-1 and EM-2 missions through investigating: Trajectory design process; Wind wavelength filtering options; Launch availability; DOL process to achieve shorter processing/uplink timeline. Trade Team consisted of personnel supporting SLS, MPCV, GSDO programs.

Decker, Ryan K.↗
NASA NTRS1998

Comparing the Ocean Color Measurements Between MOS and SeaWiFS: A Vicarious Intercalibration Approach for MOS

One of the primary goals of the NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) project is to develop methods for meaningful comparison and possible merging of data products from multiple ocean color missions. The Modular Optoelectronic Scanner (MOS) is a German instrument that was launched in the spring of 1996 on the Indian IRS-P3 satellite. With the successful launch of NASA's Sea-viewing Wide Field-of-view Sensor (SeaWiFS) in the summer of 1997, there are now two ocean color missions in concurrent operation and there is interest within the scientific community to compare data from these two sensors. In this paper, we describe our efforts to retrieve ocean optical properties from both SeaWiFS and MOS using consistent methods. We first briefly review the atmospheric correction, which removes more than 90% of the observed radiances in the visible, and then describe how the atmospheric correction algorithm used for the SeaWiFS data can be modified for application to other ocean color sensors. Next, since the retrieved water-leaving radiances in the visible between MOS and SeaWiFS are significantly different, we developed a vicarious intercalibration method to recalibrate the MOS spectral bands based on the optical properties of the ocean and atmosphere derived from the coincident SeaWiFS measurements. We present and discuss the MOS retrieved ocean optical properties before and after the vicarious calibration, and demonstrate the efficacy of this approach. We show that it is possible and efficient to vicariously intercalibrate sensors between one and another.

Wang, Menghua↗
NASA NTRS2014

Comparison of Spectral Radiance Calibration Techniques Used for Backscatter Ultraviolet Satellite Instruments

Methods for determining the absolute radiometric calibration sensitivities of backscatter ultraviolet (BUV) satellite instruments are compared as part of an effort to minimize pre-launch calibration errors. An internally illuminated integrating sphere source has been used for the Shuttle Solar BUV (SSBUV), Total Ozone Mapping Spectrometer (TOMS), Ozone Mapping Instrument (OMI), and Global Ozone Monitoring Experiment 2 (GOME-2) using standardized procedures traceable to national standards. These sphere-based sensitivities agree to within three percent [k equals 2] relative to calibrations performed using an external diffuser illuminated by standard irradiance sources, the customary radiance calibration method for BUV instruments. The uncertainty for these calibration techniques as implemented at the NASA Goddard Space Flight Centers Radiometric Calibration and Development Laboratory is shown to be 4 percent at 250nm [k equals 2] when using a single traceable calibration standard. Significant reduction in the uncertainty of nearly 1 percent is demonstrated when multiple calibration standards are used.

residual errors↗
NASA NTRS2011

Using Innovative Technologies for Manufacturing and Evaluating Rocket Engine Hardware

Many of the manufacturing and evaluation techniques that are currently used for rocket engine component production are traditional methods that have been proven through years of experience and historical precedence. As we enter into a new space age where new launch vehicles are being designed and propulsion systems are being improved upon, it is sometimes necessary to adopt new and innovative techniques for manufacturing and evaluating hardware. With a heavy emphasis on cost reduction and improvements in manufacturing time, manufacturing techniques such as Direct Metal Laser Sintering (DMLS) and white light scanning are being adopted and evaluated for their use on J-2X, with hopes of employing both technologies on a wide variety of future projects. DMLS has the potential to significantly reduce the processing time and cost of engine hardware, while achieving desirable material properties by using a layered powdered metal manufacturing process in order to produce complex part geometries. The white light technique is a non-invasive method that can be used to inspect for geometric feature alignment. Both the DMLS manufacturing method and the white light scanning technique have proven to be viable options for manufacturing and evaluating rocket engine hardware, and further development and use of these techniques is recommended.

Betts, Erin M.↗
NASA NTRS2019

Modeling transmittance of MODIS solar diffuser stability monitor sun view screen

Earlier work by Sun et al. [2005] modeled the Sun view screen transmittance of the solar diffuser stability monitor (SDSM) on Moderate Resolution Imaging Spectroradiometer (MODIS) which explains the oscillatory pattern in the Terra/Aqua MODIS SDSM Sun view response collected during the post-launch yaw maneuvers. The SDSM screen consists of small size pinholes which limit the screen transmittance. The SDSM Sun view transmittance pattern is affected by the size and distribution of pinholes, screen thickness, and orientation between the aperture stop and the Sun view screen. Planning of post-launch yaw maneuver test often requires comprehensive angular coverage to resolve the angular variation of the screen transmittance. This paper developed a Gauss-Kronrod quadrature method-based model to simulate the SDSM Sun view transmittance. This method performs iterative integration of the interception area between pinhole and aperture stop which is critical in the screen transmittance calculation. Parametric dependences of the MODIS SDSM Sun view transmittance on various geometric factors such as the pinhole size or spacing and misalignment between the SDSM Sun view screen and aperture stop are studied. The implications for the post-launch yaw maneuver planning to resolve the angular variation of the SDSM Sun view transmittance due to the SDSM Sun view screen misalignment are discussed.

MODIS↗
NASA NTRS1992

Electromagnetic launch of lunar material

Lunar soil can become a source of relatively inexpensive oxygen propellant for vehicles going from low Earth orbit (LEO) to geosynchronous Earth orbit (GEO) and beyond. This lunar oxygen could replace the oxygen propellant that, in current plans for these missions, is launched from the Earth's surface and amounts to approximately 75 percent of the total mass. The reason for considering the use of oxygen produced on the Moon is that the cost for the energy needed to transport things from the lunar surface to LEO is approximately 5 percent the cost from the surface of the Earth to LEO. Electromagnetic launchers, in particular the superconducting quenchgun, provide a method of getting this lunar oxygen off the lunar surface at minimal cost. This cost savings comes from the fact that the superconducting quenchgun gets its launch energy from locally supplied, solar- or nuclear-generated electrical power. We present a preliminary design to show the main features and components of a lunar-based superconducting quenchgun for use in launching 1-ton containers of liquid oxygen, one every 2 hours. At this rate, nearly 4400 tons of liquid oxygen would be launched into low lunar orbit in a year.

Snow, William R.↗
DOE OSTI2024

Studies of the outer-off-midplane lower hybrid wave launch scenario for plasma start-up on the TST-2 spherical tokamak

Abstract Establishment of an efficient central solenoid (CS) free tokamak plasma start-up method may lead to an economical fusion reactor. CS-free start-up using lower hybrid (LH) waves has been studied on the TST-2 spherical tokamak. Plasma current of about a quarter of CS-driven discharges has been obtained fully non-inductively using the outer-midplane and top LH launchers. Recently, an outer-off-midplane LH launcher was developed to achieve higher plasma current by optimizing for core absorption and minimal fast electron losses. Using the (outer-)off-midplane launcher, fully non-inductive plasma current start-up up to about 8 kA was achieved. Coupled ray-tracing and Fokker–Planck simulation was performed on equilibria reconstructed with an extended MHD model. It was found that the experimentally observed plasma current was in reasonable agreement with the numerical simulation. The simulation predicted appreciable orbit losses for the off-midplane launcher driven discharge at the present parameters, which was consistent with the experimentally observed x-ray radiation characteristics. The simulation showed that the current density was saturated for the present off-midplane launcher discharges and higher density and higher LH power was necessary to achieve higher plasma current.

Physics↗
NASA NTRS2010

Thermographic Methods of Detecting Insulation Voids in Large Cryogenic Tanks

Four very large (900Kgal) cryogenic liquid hydrogen and oxygen storage tanks at Kennedy Space Center's LC-39 launch pads were constructed in 1965 to support the Apollo/Saturn V Program and continue to support the Space Shuttle Program. These double-walled spherical tanks with powdered insulation in the annular region, have received minimal refurbishment or even inspection over the years. As the Shuttle Program comes to an end we now have the time to perform limited refurbishment. Thermography has been used to monitor the state of insulation as one of the four tanks was drained of cryogen and warmed to ambient temperatures. An anomalous region of insulation detected previously with thermography was confirmed by visual inspections during this period. Thermal models and a comparison of images from the cold and warm tanks suggests that the anomalous region can be detected even without cryogen in the tank. The ability to detect and correct probable insulation voids prior to filling with cryogenic fluid can provide significant cost savings by reducing commodity boil-off over many years of use.

Arens, Ellen↗
NASA NTRS2022

Low Temperature Brazing: A Candidate Method for Preventing Interplanetary Contamination During the Mars Sample Return Mission

NASA and the European Space Agency are planning a joint Mars Sample Return campaign, scheduled to launch in 2026, with a very specific objective: return to Earth the rock and regolith samples that have been collected on Mars by NASA’s Perseverance rover. This is a very complex, multi-step process intended to culminate in the safe return of Mars samples to Earth. The term “safe return” implies use of a robust containment vessel designed to prevent any uncontained or unsterilized material from Mars from being returned to Earth. Hence, any technology chosen for sealing this vessel has to meet stringent contamination requirements, but also to withstand impact forces upon landing. This paper describes the development of a primary candidate for the sealing approach: brazing.

Schein, Mike↗
NASA NTRS2002

Libration Orbit Mission Design: Applications of Numerical & Dynamical Methods

Sun-Earth libration point orbits serve as excellent locations for scientific investigations. These orbits are often selected to minimize environmental disturbances and maximize observing efficiency. Trajectory design in support of libration orbits is ever more challenging as more complex missions are envisioned in the next decade. Trajectory design software must be further enabled to incorporate better understanding of the libration orbit solution space and thus improve the efficiency and expand the capabilities of current approaches. The Goddard Space Flight Center (GSFC) is currently supporting multiple libration missions. This end-to-end support consists of mission operations, trajectory design, and control. It also includes algorithm and software development. The recently launched Microwave Anisotropy Probe (MAP) and upcoming James Webb Space Telescope (JWST) and Constellation-X missions are examples of the use of improved numerical methods for attaining constrained orbital parameters and controlling their dynamical evolution at the collinear libration points. This paper presents a history of libration point missions, a brief description of the numerical and dynamical design techniques including software used, and a sample of future GSFC mission designs.

Bauer, Frank↗
NASA NTRS1972

RAM - A concept for reducing space payload costs.

The post-Apollo era in manned space flight will be dominated in the short term by development of the space shuttle as an economical transportation system for payloads to low earth orbit. Research and Applications Modules (RAM) are a related group of shuttle-launched carriers for such payloads which can be used many times over, thus effecting great savings over currently conventional methods of implementing a program of this type. In order to maximize the potential savings, development and unit costs of the RAM vehicles must be minimized. All of the mission and operating modes can be covered in an economical fashion by the use of only three basic RAM elements - a pressurized module, an unpressurized pallet, and a pressurizable free-flying unit utilized in several combinations. These have been developed as a least cost approach through the consideration of such cost/weight related drivers as available crew size, separability of costly subsystems for multiple use, easy accessibility for maintenance/refurbishment for reuse, and a maximum commonality of hardware with existing and projected space projects.

Powell, D. J.↗
NASA NTRS1974

Chemiluminescent measurement of atmospheric acid

The design and construction of a gas phase acid sensitive analyzer are reported. These studies showed that the chemical system was a practical analytical method. A complete instrument was developed and prepared for field testing. A Titan 3-C rocket was scheduled for launching on February 11, 1974. Through preparations made by NASA Langley the instrument was set up to monitor the acid concentration in the rocket exhaust. Due to adverse wind conditions no acid was detected. This entire trip is described in detail.

Stedman, D. H.↗
NASA NTRS1974

Optimizing subsystem test programs

The goal of reduction of space system costs is pursued in the areas of standardization of subsystem test requirements as well as overall subsystem test program resource requirements. A number of standard components are being developed by NASA. The rationale for the various environmental tests applicable to future missions and launch vehicles is discussed. The need for and approach to developing standard component specifications is presented. In addition, a method for reduction of test expenditures utilizing indexes of mission effect and hardware history as indicators of test requirements is proposed.

Meyer, W. H.↗
NASA NTRS1975

Spectrum-orbit utilization - An overview

This paper discusses the problems associated with the efficient utilization of the natural resources of frequency spectrum and geo-stationary orbital arc. The nature of these resources is explained and their quantities are estimated. The present and projected future demand for them is given, and the problem areas are identified and discussed. Special emphasis is placed on mutual interference, launch limitations, propagation effects, and operational restrictions. The technical factors bearing on these problems, such as antenna patterns, modulation methods, emission restrictions, equipment characteristics, and system requirements, are discussed in detail. Some important trade-offs are presented, and special techniques that can be used to increase spectrum-orbit utilization are described. Particular emphasis is given throughout to U.S. domestic satellite communication systems.

Sawitz, P. H.↗
NASA NTRS1987

Calculation and accuracy of ERBE scanner measurement locations

The Earth Radiation Budget Experiment (ERBE) uses scanning radiometers to measure shortwave and longwave components of the Earth's radiation field at about 40 km resolution. It is essential that these measurements be accurately located at the top of the Earth's atmosphere so they can be properly interpreted by users of the data. Before the launch of the ERBE instrument sets, a substantial emphasis was placed on understanding all factors which influence the determination of measurement locations and properly modeling those factors in the data processing system. After the launch of ERBE instruments on the Earth Radiation Budget Satellite and NOAA 9 spacecraft in 1984, a coastline projection method was developed to assess the accuracy of the algorithms and data used in the location calculations. Using inflight scanner data and the coastline detection technique, the measurement location errors are found to be smaller than the resolution of the scanner instruments. This accuracy is well within the required location knowledge for useful science analysis.

Hoffman, Lawrence H.↗
NASA NTRS2002

Estimates Of The Orbiter RSI Thermal Protection System Thermal Reliability

In support of the Space Shuttle Orbiter post-flight inspection, structure temperatures are recorded at selected positions on the windward, leeward, starboard and port surfaces. Statistical analysis of this flight data and a non-dimensional load interference (NDLI) method are used to estimate the thermal reliability at positions were reusable surface insulation (RSI) is installed. In this analysis, structure temperatures that exceed the design limit define the critical failure mode. At thirty-three positions the RSI thermal reliability is greater than 0.999999 for the missions studied. This is not the overall system level reliability of the thermal protection system installed on an Orbiter. The results from two Orbiters, OV-102 and OV-105, are in good agreement. The original RSI designs on the OV-102 Orbital Maneuvering System pods, which had low reliability, were significantly improved on OV-105. The NDLI method was also used to estimate thermal reliability from an assessment of TPS uncertainties that was completed shortly before the first Orbiter flight. Results fiom the flight data analysis and the pre-flight assessment agree at several positions near each other. The NDLI method is also effective for optimizing RSI designs to provide uniform thermal reliability on the acreage surface of reusable launch vehicles.

Kolodziej, P.↗
NASA NTRS2005

Mars Science Laboratory thermal control architecture

The Mars Science Laboratory (MSL) mission to land a large rover on Mars is being planned for launch in 2009. This paper will describe the basic architecture of the thermal control system, the challenges and the methods used to overcome them by the use of an innovative architecture to maximize the use of heritage from past projects while meeting the requirements for the design.

radioisotope↗