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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 NTRS1973

Coordinate systems and lunar observing station positions

Satellite geodesy has yielded the locations of more than fifty stations in a single coordinate system referred to the earth's center of mass with accuracies in the five to ten meter range. The different methods used at Goddard to accomplish this are described, and estimates of the accuracies of the satellite determinations are discussed. Theoretical aspects of coordinate systems associated with the earth and the moon are also considered.

Siry, J. W.↗
NASA NTRS1979

Accurate measurements of mass and center of mass

Object is measured for mass and center of mass with accuracies of 0.01% and 0.14 respectively, using method that eliminates errors in alignment, leveling, and calibration. Method is applied to scientific instruments, recorder turntables, flywheels, and other devices that require precise balancing.

Chow, E. Y.↗
NASA NTRS1986

Features and technologies of ERS-1 (ESA) and X-SAR antennas

Features and technologies of planar waveguide array antennas developed for spaceborne microwave sensors are described. Such antennas are made from carbon fiber reinforced plastic (CFRP) employing special manufacturing and metallization techniques to achieve satisfactory electrical properties. Mechanical design enables deployable antenna structures necessary for satellite applications (e.g., ESA ERS-1). The slotted waveguide concept provides high aperture efficiency, good beamshaping capabilities, and low losses. These CFRP waveguide antennas feature low mass, high accuracy and stiffness, and can be operated within wide temperature ranges.

Schuessler, R.↗
NASA NTRS1991

Calorimetric output power measurements on a CW 20 kW 7.16 GHz microwave transmitter

A calorimetric measurement technique developed for NASA's Deep Space Network (DSN) transmitters that does not require data on the coolant's thermal parameters is described. Calibration of the measurement system is achieved by measuring the DC input power to the klystron and relating coolant temperature increases to this known power dissipation. Agreement between calorimetric and electrical measurements of total system power was good, the difference being less than 2 percent. The operation of the system was not greatly affected by the composition of the coolant, which was varied from pure water to 40 percent ethylene glycol by mass. Good accuracy was also shown at output power levels, which varied over a 3.6:1 range.

Perez, Raul M.↗
NASA NTRS1991

SHOOT performance testing

The Superfluid Helium On-Orbit Transfer (SHOOT) Flight Demonstration is a shuttle attached payload designed to demonstrate the technology necessary to resupply liquid helium dewars in space. Many SHOOT components will also have use in other aerospace cryogenic systems. The first of two SHOOT dewar systems has been fabricated. The ground performance testing of this dewar is described. The performance tests include measurements of heat leak, impedances of the two vent lines, heat pulse mass gauging accuracy, and superfluid transfer parameters such as flow rate and efficiency. A laboratory dewar was substituted for the second flight dewar for the transfer tests. These tests enable a precise analytical model of the transfer process to be verified. SHOOT performance is thus quantified, except for components such as the liquid acquisition devices and a phase separator which cannot be verified in one gravity.

Dipirro, M. J.↗
NASA NTRS1996

Four-Dimensional Oceanic and Atmosperic Data Assimilation with Tropical Rainfall Measuring Mission Data

An oceanic data assimilation system which allows to utilize the forthcoming Tropical Rainfall Measuring Mission (TRMM) data has been developed and applied to the Pacific Ocean to produce the velocity field. The assimilated data will be indispensable to examine the effects of rainfall and its variability on the structure and circulation of the tropical oceans and to assess the impact of global warming due to the increase of carbon dioxide on the ocean circulation system and the marine pollution caused by oil spill and ocean damping of radionuclide. The data will also provide the verification for the oceanic and ocean-atmosphere coupled General Circulation Models (GCM's). The system consists of oceanic GCM, analysis scheme and data. In the system the flow field has been determined to be physically consistent with the observed density field and the sea surface winds derived from the Special Sensor Microwave Imagery (SSM/I) data which drive the ocean current. The time integration has been performed for five years until the flow field near the surface attained the steady state starting from the rest ocean with observed temperature and salinity fields, and the SSM/I surface wind velocity. The resultant flow field showed high producibility of the system. Especially the flow near the ocean surface agreed well with available observed data. The system, for the first time, succeeded to produce the eastward subtropical current which has been discovered in the joint investigation on Kuroshio current (CSK) in the 1960s. To verify the quality of the flow field a trajectory analysis has been carried out and compared with the Algos buoy data. BRIEF DESCRIPTION OF THE DATA ASSIMILATION SYSTEM ## Oceanic GCM and analysis scheme--The basic equations are much the same as used for the GCM's, except for the Newtonian damping terms introduced into the prediction equations for the potential temperature and salinity to maintain these fields as observed. The C grid of 2'lat. by 2'long. in horizontal and the 11 vertical levels are applied to the entire Pacific Ocean. At the east and west ocean boundaries the periodic boundary conditions are applied creating fictitious ocean there. The SMAC Method is used to increase the accuracy of mass conservation. * Data--The JODC temperature and salinity data obtained from 1906 to 1988 are used in the system between Long.100'E. and 60'W. The surface wind data are derived from the SSM/I data by Dr-R. Atlas of NASA/GSFC. The data set contains every 6 hours data from July 1987 to June 1989 on the grid of 2'lat. by 2.5'long. The averaged for the whole period and then interpolated into the 2'lat. by 2'long. grid data are used to force the system. The sea bottom topography data was based on the General Bathymetric Chart of the Ocean (GEBCO) supplied by the Canadian Hydrographic Service under contract with the International Hydrographic Organization and International Oceanographic Commission of UNESCO.

Takano, Kenji↗
NASA NTRS2004

Multisensor Instrument for Real-Time Biological Monitoring

The figure schematically depicts an instrumentation system, called a fiber optic-based integration system (FOBIS), that is undergoing development to enable real-time monitoring of fluid cell cultures, bioprocess flows, and the like. The FOBIS design combines a micro flow cytometer (MFC), a microphotometer (MP), and a fluorescence-spectrum- or binding-force-measuring micro-sensor (MS) in a single instrument that is capable of measuring multiple biological parameters simultaneously or sequentially. The fiber-optic-based integration system is so named because the MFC, the MP, and the MS are integrated into a single optical system that is coupled to light sources and photometric equipment via optical fibers. The optical coupling components also include a wavelength-division multiplexer and diffractive optical elements. The FOBIS includes a laserdiode- and fiber-optic-based optical trapping subsystem (optical tweezers ) with microphotometric and micro-sensing capabilities for noninvasive confinement and optical measurement of relevant parameters of a single cell or other particle. Some of the measurement techniques implemented together by the FOBIS have long been used separately to obtain basic understanding of the optical properties of individual cells and other organisms, the optical properties of populations of organisms, and the interrelationships among these properties, physiology of the organisms, and physical processes that govern the media that surround the organisms. For example, flow cytometry yields information on numerical concentrations, cross-sectional areas, and types of cells or other particles. Micro-sensing can be used to measure pH and concentrations of oxygen, carbon dioxide, glucose, metabolites, calcium, and antigens in a cell-culture fluid, thereby providing feedback that can be helpful in improving control over a bioprocess. Microphotometry (including measurements of scattering and fluorescence) can yield further information about optically trapped individual particles. In addition to the multifunctionality not previously available in a single biological monitoring system, the FOBIS offers advantages of low mass, sensitivity, accuracy, portability, low cost, compactness (the overall dimensions of the fully developed FOBIS sensor head are expected to be less than 1 by 1 by 2 cm), and immunity to electromagnetic interference at suboptical frequencies. FOBIS could be useful in a variety of laboratory and field settings in such diverse endeavors as medical, veterinary, and general biological research; medical and veterinary diagnosis monitoring of industrial bioprocesses; and analysis of biological contaminants in air, water, and food.

Zhang, Sean (Zhanxiang)↗
NASA NTRS2019

Boundary Layer Stability and Laminar-Turbulent Transition Analysis with Thermochemical Nonequilibrium Applied to Martian Atmospheric Entry

As Martian atmospheric entry vehicles increase in size to accommodate larger payloads, transitional ow may need to be taken into account in the design of the heat shield in order to reduce heat shield mass. The mass of the Thermal Protection System (TPS) comprises a significant portion of the vehicle mass, and a reduction of this mass would result in fuel savings. The current techniques used to design entry shields generally assume fully turbulent flow when the vehicle is large enough to expect transitional flow, and while this worst-case scenario provides a greater factor of safety it may also result in overdesigned TPS and unnecessarily high vehicle mass. Greater accuracy in the prediction of transition would also reduce uncertainty in the thermal and aerodynamic loads. Stability analysis, using e(sup⁡ N) -based methods including Linear Stability Theory (LST) and the Parabolized Stability Equations (PSE), offers a physics-based method of transition prediction that has been thoroughly studied and applied in perfect gas flows, and to a more limited extent in reacting and nonequilibrium flows. These methods predict the amplification of a known disturbance frequency and allow identification of the most unstable frequency. Transition is predicted to occur at a critical amplification or N Factor, frequently determined through experiment and empirical correlations. The LAngley Stability and TRansition Analysis Code (LASTRAC), with modifications for thermochemically reacting flows and arbitrary gas mixtures, will be presented with LST results on a simulation of a high enthalpy CO2 gas wind tunnel test relevant to Martian atmospheric entry. The results indicate transition caused by modified Tollmien-Schlichting waves on the leeward side, which are predicted to be more stable and cause transition slightly downstream when thermochemical nonequilibrium is included in the stability analysis for the same mean flow solution.

Transition↗
NASA NTRS2023

Capacitive Micro-Gravity Fluid Mass Gauge

Measuring fluid mass in micro gravity, where fluid behavior is dominated by fluid properties, is a challenging problem. To address this problem engineers at NASA are developing a capacitance-based, mass-fraction gauge for vessels containing two-phase fluids. The vessel volume is enclosed with an array of electrodes, and a unique set of capacitance measurements of the enclosed volume are made between the electrodes. The capacitance measurements are scaled with appropriate weighting factors derived from Laplace's Equation to compensate for the highly non-uniform electric fields inside the measurement volume and achieve a greater level of mass fraction accuracy.

Mark A Nurge↗
NASA NTRS1991

Small body mass determination from a flyby

This paper investigates the accuracy with which the mass of a small body can be determined from a flyby. Due to the nearly linear nature of hyperbolic flybys of small bodies, analytic solutions can be derived. Four analytic solutions are developed, each of increasing complexity with different applications. These solutions are compared to a complex computer simulation for accuracy. When these methods are applied to nearly linear trajectories, the analytic solutions agree with the computer simulation results to within 4.0 percent except in one boundary case which is discussed in the text. Also described is the linear range for which these equations are applicable. These solutions are then applied to the proposed asteroid flyby of the CRAF mission to predict the mass estimate accuracy.

Sybert, Catherine B.↗
NASA NTRS2019

Rehydration Data for the Materials International Space Station Experiment (MISSE) Polymer Films

Atomic oxygen erosion of polymers in low Earth orbit (LEO) poses a serious threat to spacecraft performance and durability. Forty thin film polymer and pyrolytic graphite samples, collectively called the PEACE (Polymer Erosion and Contamination Experiment) Polymers, were exposed to the LEO space environment on the exterior of the ISS for nearly four years as part of the Materials International Space Station Experiment 1 & 2 (MISSE 1 & 2) mission. The purpose of the MISSE 2 PEACE Polymers experiment was to determine the atomic oxygen (AO) erosion yield (E(sub y), volume loss per incident oxygen atom) of a wide variety of polymers exposed to the LEO space environment. The Ey values were determined based on mass loss measurements. Because many polymeric materials are hygroscopic, the pre-flight and post-flight mass measurements were obtained using dehydrated samples. To maximize the accuracy of the mass measurements, obtaining dehydration data for each of the polymers was desired to ensure that the samples were fully dehydrated before weighing. A comparison of dehydration and rehydration data showed that rehydration data mirrors dehydration data, and is easier and more reliable to obtain. Tests were also conducted to see if multiple samples could be dehydrated and weighed sequentially. Rehydration curves of 43 polymers and pyrolytic graphite were obtained. This information was used to determine the best pre-flight, and post-flight, mass measurement procedures for the MISSE 2 PEACE Polymers experiment, and for subsequent NASA Glenn Research Center MISSE polymer flight experiments.

de Groh, Kim K.↗
NASA NTRS1975

The occultation of beta Scorpii by Jupiter. VI - The masses of beta Scorpii A1 and A2

From images of the spectroscopic binary beta Sco A, formed by the Jovian atmosphere during its 1971 May 13 occultation by Jupiter, the angular separation of the binary components was found to be 0.001496 plus of minus 0.000018 arcsec. The combination of this measurement, the elements of the spectroscopic orbit, and the parallax determination of Bertiau (1958) yields masses of 21.1 plus or minus 3.2 solar masses for the primary (B0.5 V) and 12.7 plus or minus 1.9 solar masses for the secondary. New observations are suggested for improving the accuracy of the mass determinations.

Elliot, J. L.↗
NASA NTRS1994

Factors controlling precision and accuracy in isotope-ratio-monitoring mass spectrometry

The performance of systems in which picomole quantities of sample are mixed with a carrier gas and passed through an isotope-ratio mass spectrometer system was examined experimentally and theoretically. Two different mass spectrometers were used, both having electron-impact ion sources and Faraday cup collector systems. One had an accelerating potential of 10kV and accepted 0.2 mL of He/min, producing, under those conditions, a maximum efficiency of 1 CO2 molecular ion collected per 700 molecules introduced. Comparable figures for the second instrument were 3 kV, 0.5 mL of He/min, and 14000 molecules/ion. Signal pathways were adjusted so that response times were <200 ms. Sample-related ion currents appeared as peaks with widths of 3-30 s. Isotope ratios were determined by comparison to signals produced by standard gases. In spite of rapid variations in signals, observed levels of performance were within a factor of 2 of shot-noise limits. For the 10-kV instrument, sample requirements for standard deviations of 0.1 and 0.5% were 45 and 1.7 pmol, respectively. Comparable requirements for the 3-kV instrument were 900 and 36 pmol. Drifts in instrumental characteristics were adequately neutralized when standards were observed at 20-min intervals. For the 10-kV instrument, computed isotopic compositions were independent of sample size and signal strength over the ranges examined. Nonlinearities of <0.04%/V were observed for the 3-kV system. Procedures for observation and subtraction of background ion currents were examined experimentally and theoretically. For sample/ background ratios varying from >10 to 0.3, precision is expected and observed to decrease approximately 2-fold and to depend only weakly on the precision with which background ion currents have been measured.

NASA Discipline Exobiology↗
NASA NTRS1991

The mass of Neptune

A comprehensive evaluation is conducted of the numerous attempts to estimate the mass of Neptune. It is noted that the two primary methods to mass-determination, respectively based on planetary perturbations and satellite motions, yield results of virtually equal accuracy for the mass of this planet. The attempts discussed encompass Triton observations, the values of Newcomb (1874), photographic observations, and values recently obtained from planetary and spacecraft observations.

Pierce, David A.↗
NASA NTRS2006

Mars Exploration Entry, Descent and Landing Challenges

The United States has successfully landed five robotic systems on the surface of Mars. These systems all had landed mass below 0.6 metric tons (t), had landed footprints on the order of hundreds of km and landed at sites below -1.4 km MOLA elevation due the need to perform entry, descent and landing operations in an environment with sufficient atmospheric density. At present, robotic exploration systems engineers are struggling with the challenges of increasing landed mass capability to 0.8 t while improving landed accuracy to tens of km and landing at a site as high as +2 km MOLA elevation for the Mars Science Laboratory project. Meanwhile, current plans for human exploration of Mars call for the landing of 40-80 t surface elements at scientifically interesting locations within close proximity (tens of m) of pre-positioned robotic assets. This paper summarizes past successful entry, descent and landing systems and approaches being developed by the robotic Mars exploration program to increased landed performance (mass, accuracy and surface elevation). In addition, the entry, descent and landing sequence for a human exploration system will be reviewed, highlighting the technology and systems advances required.

Entry, Descent, Landing (EDL)↗
NASA NTRS2004

AGN Black Hole Masses from Reverberation Mapping

Emission-line variability data on bright AGNs indicates that the central objects in these sources have masses in the million to few-hundred million solar mass range. The time-delayed response of the emission lines to continuum variations can be used to infer the size of the line-emitting region via light travel-time arguments. By combining these sizes with the Doppler widths of the variable part of the emission lines, a virial mass estimate can be obtained. For three especially well-studied sources, NGC 5548, NGC 7469, and 3C 390.3, data on multiple emission lines can be used to test the virial hypothesis. In each of these cases, the response time of the various emission lines is anticorrelated with the line width, with the dependence as expected for gravitationally bound motion of the line-emitting clouds, i.e., that the square of the Doppler line width is inversely proportional to the emission-line time delay. Virial masses based on the Balmer lines have now been measured for about three dozen AGNs. Systematic effects currently limit the accuracy of these masses to a factor of several, but characteristics of the radius-luminosity and mass-luminosity relationships for AGNs are beginning to emerge.

Peterson, B. M.↗
NASA NTRS2022

Study of the Mass-loss Rate from the Sun

We investigate the temporal evolution of the yearly total mass-loss rate (YTMLR) from the Sun through coronal mass ejections (CMEs) over solar cycles 23 and 24. The mass determination of CMEs can be subject to significant uncertainty. To minimize this problem, we have used extensive statistical analysis. For this purpose, we employed data included in the Coordinated Data Analysis Workshop (CDAW) catalog. We estimated the contributions to mass loss from the Sun from different subsamples of CMEs (selected on the basis of their masses, angular widths, and position angles). The temporal variations of the YTMLR were compared to those of the sunspot number (SSN), X-ray flare flux, and the Disturbance Storm Time (Dst) index. We show that the CME mass included in the CDAW catalog reflects with high accuracy the actual mass-loss rate from the Sun through CMEs. Additionally, it is shown that the CME mass distribution in the log-lin representation reflects the Gaussian distribution very well. This means that the CMEs included in the CDAW catalog form one coherent population of ejections that have been correctly identified. Unlike the CME occurrence rate, it turns out that the YTMLR is a very good indicator of solar activity (e.g., SSN) and space weather (e.g., Dst index) consequences. These results are very important, since the YTMLR, unlike the mass loss through solar wind, significantly depends on solar cycles.

the sun↗
NASA NTRS2010

MISSE 2 PEACE Polymers Experiment Atomic Oxygen Erosion Yield Error Analysis

Atomic oxygen erosion of polymers in low Earth orbit (LEO) poses a serious threat to spacecraft performance and durability. To address this, 40 different polymer samples and a sample of pyrolytic graphite, collectively called the PEACE (Polymer Erosion and Contamination Experiment) Polymers, were exposed to the LEO space environment on the exterior of the International Space Station (ISS) for nearly 4 years as part of the Materials International Space Station Experiment 1 & 2 (MISSE 1 & 2). The purpose of the PEACE Polymers experiment was to obtain accurate mass loss measurements in space to combine with ground measurements in order to accurately calculate the atomic oxygen erosion yields of a wide variety of polymeric materials exposed to the LEO space environment for a long period of time. Error calculations were performed in order to determine the accuracy of the mass measurements and therefore of the erosion yield values. The standard deviation, or error, of each factor was incorporated into the fractional uncertainty of the erosion yield for each of three different situations, depending on the post-flight weighing procedure. The resulting error calculations showed the erosion yield values to be very accurate, with an average error of 3.30 percent.

McCarthy, Catherine E.↗