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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 NTRS1984

Monte Carlo calculations of elementary particle properties

The object of this project is to calculate the masses of the elementary particles. This ambitious goal apparently is not possible using analytic methods or known approximation methods. However, it is probable that the power of a modern super computer will make at least part of the low lying mass spectrum accessible through direct numerical computation. Initial attempts by several groups at calculating this spectrum on small lattices of space time points have been very promising. Using new methods and super computers considerable progress has been made towards evaluating the mass spectrum on comparatively large lattices. Only more time and faster machines with increased storage will allow calculations of systems with guaranteed minimal boundary effects. The ideas that currently go into this calculation are outlined.

Guralnik, G. S.↗
NASA NTRS1994

Determining structure in molecular clouds

We descibe an automatic, objective routine for analyzing the clumpy structure in a spectral line position-position-velocity data cube. The algorithm works by first contouring the data at a multiple of the rms noise of the observations, then searches for peaks of emission which locate the clumps, and then follows them down to lower intensities. No a proiri clump profile is assumed. By creating simulated data, we test the performance of the algorithm and show that a contour map most accurately depicts internal structure at a contouring interval equal to twice the rms noise of the map. Blending of clump emission leads to small errors in mass and size determinations and in severe cases can result in a number of clumps being misidentified as a single unit, flattening the measured clump mass spectrum. The algorithm is applied to two real data sets as an example of its use. The Rosette molecular cloud is a 'typical' star-forming cloud, but in the Maddalena molecular cloud high-mass star formation is completely absent. Comparison of the two clump lists generated by the algorithm show that on a one-to-one basis the clumps in the star-forming cloud have higher peak temperatures, higher average densities, and are more gravitationally bound than in the non-star-forming cloud. Collective properties of the clumps, such as temperature-size-line-width-mass relations appear very similar, however. Contrary to the initial results reported in a previous paper (Williams & Blitz 1993), we find that the current, more thoroughly tes ted analysis finds no significant difference in the clump mass spectrum of the two clouds.

Williams, Jonathan P.↗
NASA NTRS1978

Fragmentation of molecular clouds

Fragmentation is generally considered to be the initial process that a molecular cloud must undergo before stars can form. Yet its role in determining the final mass spectrum remains obscure. It appears that gravitational fragmentation, considered as a unique process, is unsatisfactory. Both fragmentation and complementary physical processes are, therefore, discussed. One of the principle aims of the discussion is to indicate how stars of solar mass (and more generally, how the initial mass spectrum of stars) can form. Attention is given to the evidence for fragmentation, opacity-limited fragmentation, magnetic flux-limited fragmentation, fragmentation induced by molecule formation and excitation, protostellar heat input, fragment coalescence, accretion, binary formation, and probabilistic theories.

Silk, J.↗
NASA NTRS1979

Collisional evolution of the mass-distribution spectrum of planetesimals. II

An investigation of conditions for the early growth of planetesimals through their mutual collisions using Monte Carlo technique is presented. Rebound, erosion, catastrophic breakup, and coagulation are considered, mean random velocity is assumed to vary with time, and growth of km-sized planetesimals is shown to occur only when they have the mechanical properties similar to iron meteorites. The formation time of several hundred-km sized planetesimals is much longer than previously reported by Greenberg (1978), and an expression was derived for the temporal variation of the mean mass.

Matsui, T.↗
NASA NTRS1993

A Remote Laser-mass Spectrometer for Determination of Elemental Composition

Determination of the elemental composition of lunar, asteroid, and planetary surfaces is a major concern for science and resource utilization of space. The science associated with the development of a satellite or lunar rover laser-mass spectrometer instrument is presented here. The instrument would include a pulsed laser with sufficient energy to create a plasma on a remote surface. Ions ejected from this plasma travel back to the spacecraft or rover, where they are analyzed by a time-of-flight mass spectrometer, giving the elemental and isotope composition. This concept is based on the LIMA-D instrument on board the former Soviet Union Phobos-88 spacecraft sent to Mars. A laser-mass spectrometer placed on a rover or satellite would substantially improve the data return over alternative techniques. The spatial resolution would be centimeters, and a complete mass spectrum could be achieved in one laser shot. An experiment is described that demonstrates these features. A 400 mj Nd:YAG laser is focused, to an intensity of 10(exp 11) w/sq cm, onto a Al, Ag, Cu, Ge, or lunar simulant target. A plasma forms from which ions are ejected. Some of these ions travel down an 18-m evacuated flight tube to a microchannel plate detector. Alternatively, the ions are captured by an ion trap where they are stored until pulsed into a 1-m time-of-flight mass spectrometer, giving the elemental composition of the remote surface. A television camera monitors the plasma plume shape, and a photodiode monitors the temporal plasma emission . With this system, ions of Al, Ag, Cu, Ge, and lunar simulant have been detected at 18 m. The mass spectrum from the ion trap and 1-m time-of-flight tube will be presented.

Deyoung, R. J.↗
NASA NTRS1978

Mass spectrometer calibration standard

Inert perfluorinated alkane and alkyl ethers mixture is used to calibrate mass spectrometer. Noncontaminating, commercially-available liquid provides series of reproducible reference peaks over broad mass spectrum that ranges over mass numbers from 1 to 200.

Ross, D. S.↗
NASA NTRS1976

The Viking mission search for life on Mars

The scientific payload on the Viking Mars landers is described. Shortly after landing, two facsimile cameras capable of stereoscopic imaging will scan the landing site area in black and white, color, and infrared to reveal gross evidence of past or present living systems. A wide range mass spectrometer will record a complete mass spectrum for soil samples from mass 12 to mass 200 every 10.3 sec. Three experiments based on different assumptions on the nature of life on Mars, if it exists, will be carried out by the bio-lab. A pyrolytic release experiment is designed to measure photosynthetic or dark fixation of carbon dioxide or carbon monoxide into organic compounds. A labelled release experiment will test for metabolic activity during incubation of a surface sample moistened with a solution of radioactively labelled simple organic compounds. A gas exchange experiment will detect changes in the gaseous medium surrounding a soil sample as the result of metabolic activity. The hardware, function, and terrestrial test results of the bio-lab experiments are discussed.

Klein, H. P.↗
NASA NTRS2017

Mass Spectra Deconvolution of Gaseous Mixtures Containing Volatile Organic Compounds

The Spacecraft Atmosphere Monitor (S.A.M.) analyzes all gaseous pollutants in the 1-150Th mass-to-charge range based on their positive-ion mass spectra. Of particular interest is the Trace Gas Analysis (TGA) mode of operation in which S.A.M detects minute amounts of volatile organic compounds (VOC). Pollutant component of the ambient air is sampled on demand in twenty full mass spectra per second. All spectra is accumulated in two-second intervals by an on-board Field Programmable Gate Arrays (FPGA) unit. Mass spectra represents the number of detected fragment ions in a given mass-to-charge ratio channel. Electron impact ionization of neutral molecules results in creation of numerous fragment ions and most of organic compounds will contribute several identical fragments. Despite the presence of these molecular isobars, we developed the deconvolution algorithm capable of identifying target species based on their characteristic fragmentation patterns. We investigate the efficiency of deconvolution algorithm as a function of mass resolution with which mass spectrum is acquired. Higher the mass resolution, better the chances are to distinguish between stereoisomers using their fragmentation propensities, but also results in higher data volumes to be processed by a set of small footprint software stacks hosted by an on-board computer. Finding the balance between deconvolution accuracy and generated data volume under time constrains and limited computing resources is the main topic of this study.

Darrach, M.↗
NASA NTRS2004

The ULX Population in the Starburst Galaxy NGC 253

Optimism is mounting for the existence of intermediate mass black holes (IMBH), which occupy the mass spectrum somewhere between the stellar-mass and supermassive varieties. IMBH are naturally predicted by theoretical stellar and black hole evolution models, but the strong attention to them began only recently with the discovery of ultraluminous x-ray sources (ULX). If isotropic and accreting normally, ULX have luminosities tens to thousands of times greater than the Eddington luminosity of a neutron star or stellar-mass black hole. A standard interpretation of their x-ray flux implies that they are powered by IMBH. On the other hand, they may be stellar-mass black holes that are beamed or emit anisotropically. Therefore, the exact nature of ULX is highly controversial. ULX are common in starburst galaxies. At a distance of only 3 Mpc, NGC 253 is bright, nearby, and one of the best-studied starburst galaxies. Approximately 50 distinct x-ray point sources are detected in or near the plane of the galaxy. At least six of these are ULX, with luminosities greater than 10 times that expected for a stellar-mass, accreting compact object. We present new Chandra data from an 80 ksec observation of NGC 253 obtained in 2003 that provides high quality spectra of these sources. Comparing the 1999 and 2003 Chandra observations, the sources have varied significantly over the course of four years, with one of the ULX disappearing completely. The ULX spectra are similar to black-hole XRBs and at least one appears to possess an iron K line. We will discuss what insight these data provide for the nature of ULX in NGC 253 .

Weaver, K. A.↗
NASA NTRSDate not supplied

Non-Targeted Direct Infusion Soluble Organic Analysis on a Tarda Meteorite Extract

The differences in chemistry, mineralogy, and structure of chondrites demonstrate thevariations in time/space of their forming regions in the solar nebula. In contrast, the variationof the organic reserves in the solar nebula is unclear. Furthermore, their subsequent evolutionof organic matter on the parent body is still under debate. In a previous study on Tagish Lake(C2 ungrouped) we showed that the primordial soluble organic matter (SOM) could bedistinguished from the parent body's secondary alteration threw mass distribution. This studywill show the Tarda meteorite SOM primordial distribution, using the model from ourprevious study. We discuss its organic reservoirs and secondary alteration effects. We alsocompare the character of the SOM with previously analysed Orgueil (CI). Sample and method: Tarda (fall, 2020) was classified as a C2 ungroup carbonaceouschondrite. Its bulk three oxygen isotope composition is distinct from other chondrite groupsbut similar to CI-chondrite-like and Yamato-type-like [1] values. We analysed themethanol/toluene extract using the high-resolution Orbitrap mass spectrometer at the Institutede Planétologie et d’Astrophysique Grenoble (IPAG) by directly injecting and ionizing theSOM and the solvent using the Heated Electrospray Ionization (HESI) source. After thespectra acquisition, the in-house developed post-processing data analysis tools, Attributor [2],was used. Preliminary Result: The SOM mass distribution of Tarda was well-fitted by the modelinterpreted as the primordial SOM distribution in Tagish lake. This common distributionpattern implies the presence of a common organic reservoir or SOM formation mechanism.Orgueil’s mass spectrum showed a more complex mass-distribution and seemed to be affectedby secondary processes. In contrast to the mass-distribution, SOM’s elemental abundance wasdistinct. The Tarda extract was enriched in S-bearing organic compounds which was incontrast to the Tagish Lake extract consisting of mostly CHNO elements. The presentationwill also discuss the application of our technique to Ryugu or Bennu samples. [1] Meteoriticalbulletin database [2] Orthous-Daunay, F. R. et al. (2019) Geochemical Journal, 53(1), 21-32

J Isa↗
NASA NTRS1983

Methylhydrazinium nitrate

Methylhydrazinium nitrate was synthesized by the reaction of dilute nitric acid with methylhydrazine in water and in methanol. The white needles formed are extremely hygroscopic and melt at 37.5-40.5 C. The IR spectrum differs from that reported elsewhere. The mass spectrum exhibited no parent peak at 109 m/z, and thermogravimetric analysis indicated that the compound decomposed slowly at 63-103 C to give ammonium and methylammonium nitrate. The density is near 1.55 g/cu cm.

Lawton, E. A.↗
NASA NTRS2016

Advanced Laser Architecture for Two-Step Laser Tandem Mass Spectrometer

Future astrobiology missions will focus on planets with significant astrochemical or potential astrobiological features, such as small, primitive bodies and the icy moons of the outer planets that may host diverse organic compounds. These missions require advanced instrument techniques to fully and unambiguously characterize the composition of surface and dust materials. Laser desorptionionization mass spectrometry (LDMS) is an emerging instrument technology for in situ mass analysis of non-volatile sample composition. A recent Goddard LDMS advancement is the two-step laser tandem mass spectrometer (L2MS) instrument to address the need for future flight instrumentation to deconvolve complex organic signatures. The L2MS prototype uses a resonance enhanced multi-photon laser ionization mechanism to selectively detect aromatic species from a more complex sample. By neglecting the aliphatic and inorganic mineral signatures in the two-step mass spectrum, the L2MS approach can provide both mass assignments and clues to structural information for an in situ investigation of non-volatile sample composition. In this paper we will describe our development effort on a new laser architecture that is based on the previously flown Lunar Orbiter Laser Altimeter (LOLA) laser transmitter for the L2MS instrument. The laser provides two discrete midinfrared wavelengths (2.8 m and 3.4 m) using monolithic optical parametric oscillators and ultraviolet (UV) wavelength (266 nm) on a single laser bench with a straightforward development path toward flight readiness.

Laser↗
NASA NTRS1986

Dust density and mass distribution near comet Halley from Giotto observations

The density and the mass spectrum of the dust near comet Halley have been measured by the Giotto space probe's dust impact detection system. The dust spectrum obtained at 291,000 km from the comet nucleus show depletion in small and intermediate masses; at about 600 km from the nucleus, however, the dust activity rises and the spectrum is dominated by larger masses. Most of the mass striking Giotto is noted to reside in the few large particles penetrating the dust shield. Momentum balances and energy considerations applied to an observed deceleration suggest that a large mass of the spacecraft was detached by an impact.

Mcdonnell, J. A. M.↗
NASA NTRS1966

Highly sensitive solids mass spectrometer uses inert-gas ion source

Mass spectrometer provides a recorded analysis of solid material surfaces and bulk. A beam of high-energy inert-gas ions bombards the surface atoms of a sample and converts a percentage into an ionized vapor. The mass spectrum analyzer separates the vapor ionic constituents by mass-to-charge ratio.

Source record↗
NASA NTRS1985

Operation of a microchannel plate counting system in a mass spectrometer

A multiplier detector system has been developed as part of a mass spectrometer in an ion counting mode. During its operation ions striking a microchannel plate release pulses of electrons which are accelerated to a phosphor layer. The resulting flash of light is carried by a fiber-optic bundle to a photodiode array. The detector simultaneously counts ions throughout a mass spectrum covering more than 30 amu. It extends the mass spectrometer's operation toward low count rates for trace gas analysis. Each mass peak can be independently measured at count rates between 0.1 and 1000 counts/s. Higher rates on a few peaks do not blind the entire detector. The detector's capabilities have been demonstrated by measuring Kr and Xe isotopes in air at natural abundances. The mass spectrometer, detector, and readout electronics are sufficiently compact to permit use in a balloon-borne experiment.

Murphy, D. M.↗
NASA NTRS1993

A hydrodynamic treatment of the tilted cold dark matter cosmological scenario

A standard hydrodynamic code coupled with a particle-mesh code is used to compute the evolution of a tilted cold dark matter (TCDM) model containing both baryonic matter and dark matter. Six baryonic species are followed, with allowance for both collisional and radiative ionization in every cell. The mean final Zel'dovich-Sunyaev y parameter is estimated to be (5.4 +/- 2.7) x 10 exp -7, below currently attainable observations, with an rms fluctuation of about (6.0 +/- 3.0) x 10 exp -7 on arcmin scales. The rate of galaxy formation peaks at a relatively late epoch (z is about 0.5). In the case of mass function, the smallest objects are stabilized against collapse by thermal energy: the mass-weighted mass spectrum peaks in the vicinity of 10 exp 9.1 solar masses, with a reasonable fit to the Schechter luminosity function if the baryon mass to blue light ratio is about 4. It is shown that a bias factor of 2 required for the model to be consistent with COBE DMR signals is probably a natural outcome in the present multiple component simulations.

Cen, Renyue↗
NASA NTRS1963

SPUTTERING ION SOURCE FOR SOLIDS

Sputtering argon ion source used for analysis of solids provides more stable operation than a spark source and allows electrometric recording of the mass spectrum

MASS SPECTROSCOPY↗