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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Microanalytical study of some cosmic dust discovered in sea-floor sediments in China

The study of cosmic dust can provide useful data in the investigation of the origin of the Earth and the evolution of celestial bodies. Three types of cosmic dust (ferriginous, siliceous, and glassy) were discovered in the seafloor sediments near China. Their chemical composition and microstructure were examined by X-ray diffraction, fractography, and electron microscopy. The major mineral in an iron-containing cosmic dust is magnetite. The silicate spheres contain sundry metals and metal oxides. Glassy microtektites are similar in composition to tektites, and are found in all the major meteorite areas worldwide.

Shijie, Z.↗
NASA NTRS1985

Newly Discovered Martian Impact Basins

Three previously unrecognized Martian impact basins were discovered through detailed mapping of landforms, structures and terrains near Cassini and Al Qahira basins. Al Qahira A lies on the Martian dichotomy boundary and intersects the older basin, Al Qahira. It has four rings that are expressed by a variety of landforms. Southwestward Al Qahira A is out by a younger Basin, Al Qahira B. Al Qahira B is a highly degraded basin with one identifiable ring. Its ring is expressed by a few massifs, knobs and inward-facing scarps, but is recognized by the distributions of wrinkle ridges and plains units. Cassini A lies southward of the younger Cassini Basin and is intersected by it. It probably has four rings. The importance of detailed mapping of various types of landforms and terrains to the discovery of basins on Mars are demonstrated.

Stam, M.↗
NASA NTRS1985

E2000 + 223 - A newly discovered old nova?

The X-ray source, E2000 + 223, serendipitously discovered by the Einstein Observatory, has been tentatively identified with an old nova shell. Spectroscopic observations of the diffuse optical counterpart show a heavily reddened continuum with bright forbidden S II emission lines at double lambda 6716, 6732. Radio observations at the VLA show a weak (about 1.2 mJy) extended radio source, with a nonthermal spectrum, concident with the optical emission. The observations can be best explained by assuming the object is an old nova which erupted sometime in the eighteenth or nineteenth century, similar to GK Per (Nova 1901) but at a distance of 1.4 kpc.

Takalo, L. O.↗
NASA NTRS1986

New X-ray and optical observations of the X-ray discovered QSO-galaxy pair 1E 0104.2 + 3153

New X-ray and optical observations are presented of the QSO-galaxy pair 1E 0104.2 + 3153, originally discovered as a serendipitous source in the Einstein Observatory Medium Sensitivity Survey (Gioia et al., 1984). Results from an extremely deep Exosat observation are used to suggest that the QSO rather than the compact group of galaxies is the optical counterpart of the IPC source. High-resolution (1-A) spectroscopy of the broad-absorption-line QSO, which fails to confirm the Ca II H and K absorption features reported by Stocke et al., (1984), is presented and discussed. The presence of broad absorption lines in the QSO spectrum may indicate that intrinsic absorption is the cause of the nondetection of this source in the soft Exosat energy band. Optical monitoring of the QSO over a 2-yr period indicates variability. Possible interpretations of this phenomenon are intrinsic luminosity variation or a cessation of a gravitational lensing effect acting at the time of the Einstein observation.

Gioia, I. M.↗
NASA NTRS1990

Interpretation of the newly discovered submillimeter water maser

The 10(29)-9(36)321 GHz water maser discovered recently by Menten et al. (1990) may be pumped collisionally under a wide range of physical conditions. This range of conditions is similar but not identical to that required to excite the well-studied 22 GHz water maser. The ratio of the observed 22 GHz and 321 GHz intersteller maser luminosities can be explained by collisional excitation within the same warm, dense gas. Collisional pumping in a circumstellar envelope can account for the observed 321 GHz maser emission in the supergiant star VY CMa.

Neufeld, David A.↗
NASA NTRS1990

Data base on physical observations of near-Earth asteroids and establishment of a network to coordinate observations of newly discovered near-Earth asteroids

This program consists of two tasks: (1) development of a data base of physical observations of near-earth asteroids and establishment of a network to coordinate observations of newly discovered earth-approaching asteroids; and (2) a simulation of the surface of low-activity comets. Significant progress was made on task one and, and task two was completed during the period covered by this progress report.

Davis, D. R.↗
NASA NTRS1992

Thirteen new BL Lacertae objects discovered by an efficient x ray/radio/optical technique

The discovery of 13 serendipitous BL Lac objects in the Einstein IPC Slew Survey by means of x ray/radio vs. x ray/optical color-color diagrams and confirmation by optical spectroscopy are reported. These 13 BL Lacs were discovered using a technique which exploits the characteristic broad band spectra of BL Lacs. New VLA detections provide accurate fluxes (f(6 cm) is approximately 0.5 mJy) and 2 in. positions, facilitating the determination of an optical counterpart. All 13 new BL Lacs show essentially featureless optical spectra. Nine of these lie within the range of colors of known x ray selected BL Lacs. Of the remaining four, one is apparently x ray louder (by a factor of 1.5) or optically quieter (by 0.8 mags); and three are optically louder (by 1-1.3 mags) than x ray selected BL Lacs. Approximately 50 new BL Lacs in total are expected from VLA work and upcoming Australia Telescope observations, yielding a complete Slew Survey sample of approximately 90 BL Lacs.

Schachter, Jonathan F.↗
NASA NTRS1993

Finding the rarest objects in the universe: A new, efficient method for discovering BL Lacertae objects

We present a new, efficient method for discovering new BL Lac Objects based upon the results of the Einstein Extended Medium Sensitivity Survey (EMSS). We have found that all x-ray selected BL Lacs are radio emitters, and further, that in a 'color-color' diagram (radio/optical and optical/x-ray) the BL Lac Objects occupy an area distinct from both radio loud quasars and the radio quiet QSOs and Seyferts which dominate x-ray selected samples. After obtaining radio counterparts via VLA 'snapshot' observations of a large sample of unidentified x-ray sources, the list of candidates is reduced. These candidates then can be confirmed with optical spectroscopy and/or polarimetry. Since greater than 70 percent of these sources are expected to be BL Lacs, the optical observations are very efficient. We have tested this method using unidentified sources found in the Einstein Slew Survey. The 162 Slew Survey x-ray source positions were observed with the VLA in a mixed B/C configuration at 6 cm resulting in 60 detections within 1.5 position error circle radii. These x-ray/optical/radio sources were then plotted, and 40 BL Lac candidates were identified. To date, 10 candidates have been spectroscopically observed resulting in 10 new BL Lac objects! Radio flux, optical magnitude, and polarization statistics (obtained in white light with the Steward Observatory 2.3 m CCD polarimeter) for each are given.

Stocke, John↗
NASA NTRS1993

Two newly discovered millisecond pulsars

Two millisecond pulsars have been discovered in the course of systematic surveys being made with the Arecibo radio telescope. PSR J2019 + 2425 has a 3.935 ms period and moves in a nearly circular, 76.5 day orbit around a about 0.3 solar mass companion. PSR J2322 + 2057, with a period of 4.808 ms, is an isolated object. The two pulsars have unusually small period derivatives, corresponding to spin-down time scales of 7.5 +/- 0.5 and 11 +/- 5 Gyr, respectively. Both objects show pulse time-of-arrival residuals no larger than a few microseconds over many months, lending further support to the observation that 'recycled' pulsars have extremely stable rotational behavior. The timing results also confirm that physics related to the rotational dynamics of these strongly self-gravitating stars - in particular, the value of the gravitational coupling constant G - remains essentially constant over time scales comparable to the Hubble time. Dispersion measures of the two pulsars indicate distances of 0.8-0.9 kpc.

Nice, D. J.↗
NASA NTRS1993

The new BL Lacertae objects discovered by an efficient X-ray/radio/optical technique

We report the recent discovery of ten BL Lac objects in the Einstein IPC Slew Survey by means of X-ray/radio versus X-ray/optical color-color diagrams and confirming optical spectroscopy. These ten BL Lac objects were discovered using a technique proposed by Stocke et al. (1989) which exploits the characteristic broad-band spectra of BL Lac objects. New VLA detections provide accurate fluxes (limiting f(6 cm) about 0.5 mJy) and about 1 arcsec positions, facilitating the determination of an optical counterpart. All ten new BL Lac objects show essentially featureless optical spectra and lie within the range of radio/X-ray/optical colors of known X-ray-selected BL Lac objects, when about 1 mag optical variability is included. We expect about 50 new BL Lac objects in total, from complete optical follow-up of our now completed VLA work and recent Australia Telescope observations, yielding a complete Slew Survey sample of about 90 BL Lac objects.

Schachter, Jonathan F.↗
NASA NTRS1994

Discovering operating modes in telemetry data from the Shuttle Reaction Control System

This paper addresses the problem of detecting and diagnosing faults in physical systems, for which suitable system models are not available. An architecture is proposed that integrates the on-line acquisition and exploitation of monitoring and diagnostic knowledge. The focus is on the component of the architecture that discovers classes of behaviors with similar characteristics by observing a system in operation. A characterization of behaviors based on best fitting approximation models is investigated. An experimental prototype has been implemented to test it. Preliminary results in diagnosing faults of the reaction control system of the space shuttle are presented. The merits and limitations of the approach are identified and directions for future work are set.

Manganaris, Stefanos↗
NASA NTRS2001

Discovering Communicable Scientific Knowledge from Spatio-Temporal Data

This paper describes how we used regression rules to improve upon a result previously published in the Earth science literature. In such a scientific application of machine learning, it is crucially important for the learned models to be understandable and communicable. We recount how we selected a learning algorithm to maximize communicability, and then describe two visualization techniques that we developed to aid in understanding the model by exploiting the spatial nature of the data. We also report how evaluating the learned models across time let us discover an error in the data.

Schwabacher, Mark↗
NASA NTRS2003

ASCA and Bepposax Observations of the Newly Discovered SNR RX J0852-4622

This grant supports an investigation of the supernova remnant RX J0852-4622 (G266.1-1.2), a large-diameter, nearby SNR for which the X-ray emission is dominated by nonthermal processes. As only the third such SNR discovered, for which there is direct evidence of cosmic-ray acceleration dominating the SNR dynamics, this is an exceptionally important object. Our progress on this study to date has been good. We have published the results of a spectral mapping of the XNR as well as the identification of a compact X-ray source which may be the associated neutron star. Our final work involves modeling of the emission using limits from the radio flux in order to estimate the inverse-Compton flux that might be observable in the TeV gamma-ray regime. We have just completed similar modeling of the emission from G347.3-0.5 (Lazendic et al. - submitted to ApJ), and the results have drawn considerable interest in the gamma-ray community (Slane 2002; astro-ph/0212353). Extensive observations of G266.1--1.2 with the CANGAROO TeV gamma-ray telescope have been carried out, and our modeling of the broad-band emission characteristic are of importance for such studies.

Slane, Patrick↗
NASA NTRS2002

Discovering Communicable Models from Earth Science Data

This chapter describes how we used regression rules to improve upon results previously published in the Earth science literature. In such a scientific application of machine learning, it is crucially important for the learned models to be understandable and communicable. We recount how we selected a learning algorithm to maximize communicability, and then describe two visualization techniques that we developed to aid in understanding the model by exploiting the spatial nature of the data. We also report how evaluating the learned models across time let us discover an error in the data.

Schwabacher, Mark↗
NASA NTRS2003

ASCA and Bepposax Observations of the Newly Discovered SNR RX J0852-4622

The NASA Grant supported analysis of X-ray data from the supernova remnant (SNR) G266.2-1.2, a newly discovered SNR in the direction of Vela. Our observations reveal that the X-ray emission from this remnant is nonthermal, making this the third shell-type SNR for which the X-ray emission is dominated by synchrotron processes. The interpretation is that the SNR is an efficient accelerator of cosmic rays, with direct evidence of electrons at energies approaching 100 TeV. Our spectral analysis indicates a higher absorption than for the Vela SNR, indicating that G266.2-1.2 is more distant. However, we conclude that the lack of high amounts of absorption place the remnant closer than the Vela molecular ridge at a distance of 1-2 kpc. We observe a compact X-ray source at the remnant center, surrounded by diffuse emission, which may be an associated neutron star.

Oliversen, Ronald J.↗
NASA NTRS2004

More Far-Side Deep Moonquake Nests Discovered

As reported last year, we started to reanalyze the seismic data acquired from 1969 to 1977 with a network of stations established on the Moon during the Apollo mission. The reason for the reanalysis was because recent advances in computer technology make it possible to employ much more sophisticated analysis techniques than was possible previously. The primary objective of the reanalysis was to search for deep moonquakes on the far side of the Moon and, if found, to use them to infer the structure of the Moon's deep interior, including a possible central core. The first step was to identify any new deep moonquakes that escaped our earlier search by applying a combination of waveform cross-correlation and single-link cluster analysis, and then to see if any of them are from previously unknown nests of deep moonquakes. We positively identified 7245 deep moonquakes, more than a five-fold increase from the previous 1360. We also found at least 88 previously unknown deep-moonquake nests. The question was whether any of these newly discovered nets were on the far side of the Moon, and we now report that our analysis of the data indicates that some of them are indeed on the far side.

Nakamura, Y.↗
NASA NTRS1999

Did Viking discover life on Mars?

A major argument in the claim that life had been discovered during the Viking mission to Mars is that the results obtained in the Labeled Release (LR) experiment are analogous to those observed with terrestrial microorganisms. This assertion is critically examined and found to be implausible.

Non-NASA Center↗
NASA NTRS2005

Discovering New Drugs on the Cellular Level

With the Vision for Space Exploration calling for a sustained human presence in space, astronauts will need to grow plants, while in orbit, for nourishment that they will not receive from only consuming dehydrated foods. As a potential source of food for long-duration missions, space-grown plants could also give astronauts an important psychological boost, as fresh vegetables could serve as a welcomed change from monotonous meals consisting of reconstituted foods in plastic bags. Even more, these plants could likely aid in the recycling of air and wastewater on spacecraft. With a helping hand from a company by the name of Biolog, Inc., NASA is studying the impacts of decreased gravity and spaceborne bacteria on the plants being grown for food in space. With a helping hand from NASA, this very same company is creating powerful new cell- and bacteria-analysis tools for use in discovering and developing new drugs on Earth.

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