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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Improvements to the Photometric response and positional accuracy of the Yale PDS 2020G microdensitometer

The necessity to incorporate several hardware changes to optimize the Yale PDS 2020G microdensitometer for photometric and astrometric research are discussed. The properties of a new high speed photometer and a positional calibration system are described. The new photometer incorporates a high speed logarithmic analog to digital converter with more than 10 times the resolution of the former system and a cycle time of approximately 50 usec. The positional calibration system monitors the drunkenness of the stages with respect to fixed index lines and enables the correction of the +/- 5 micro stage errors to an accuracy of better than 1 micro.

Lee, J. F.↗
NASA NTRS1984

A microprocessor-based control system for the Vienna PDS microdensitometer

The Motorola Exorset 30 system, based on a Motorola 6809 microprocessor which serves as control processor for the microdensitometer is presented. User communication and instrument control are implemented in this syatem; data transmission to a host computer is provided via standard interfaces. The Vienna PDS system (VIPS) software was developed in BASIC and M6809 assembler. It provides efficient user interaction via function keys and argument input in a menu oriented environment. All parameters can be stored on, and retrieved from, minifloppy disks, making it possible to set up large scanning tasks. Extensive user information includes continuously updated status and coordinate displays, as well as a real time graphic display during scanning.

Jenkner, H.↗
NASA NTRS2002

Non-Thermal Hard X-Ray Emission in Galaxy Clusters Observed with the BeppoSAX PDS

We studied the X-ray emission in a sample of clusters using the BeppoSAX PDS instrument in the 20 -- 80 keV energy band. We estimated the non-thermal cluster emission (HXR) by modeling the thermal contribution from the cluster gas and the non-thermal contamination from the AGN in the field, and propagating the corresponding uncertainties. We also evaluated and propagated the systematic uncertainties due to the background fluctuations. The resulting non-thermal component is detected at a sigma level in approx. 50 % of the non-significantly AGN-contaminated clusters, i.e. in clusters A2142, A2256, A3376, Coma, Ophiuchus and Virgo. Furthermore, Virgo is detected at a 4 sigma level. All the clusters detected at a 2 sigma level exhibit some degree of merger signatures, i.e. deviations from the azimuthally symmetric brightness and temperature distributions, while the relaxed clusters are detected at a lower confidence. The data are consistent with a scenario whereby relaxed clusters have no non-thermal hard X-ray component, whereas merger clusters do, with a 20 -- 80 keV luminosity of approx. 10(exp 42-44)((h(sub 50))(exp -2))(erg/s). Consistent with merger boosting of cluster temperatures, the non-thermal luminosity increases by 2-3 orders of magnitude between the average cluster temperatures 2 and 10 keV, as L(sub NTE) is proportional to T(sup j) with j = 2.4+/-0.3. These results corroborate the assumption which is the essential element in most non-thermal hard X-ray emission models. The co-added spectrum of all non-significantly AGN-contaminated clusters indicates a power-law spectrum for the non-thermal component with a photon index of 1.5+/-0.25 at 1 sigma confidence level. Unless there is a high energy cut-off in the electron velocity distribution, the total spectrum implies that Inverse Compton scatter of Cosmic Microwave Background photons from electron population dominates over the non-thermal bremsstrahlung in producing hard X-rays in clusters on the merger shock acceleration of electrons in clusters.

Nevalainen, Jukka H.↗
NASA NTRS2004

Non-Thermal Hard X-Ray Emission in Galaxy Clusters Observed with the BeppoSAX PDS

We study the X-ray emission in a sample of galaxy clusters using the BeppoSAX PDS instrument in the 20-80 keV energy band. We estimate the nonthermal hard X-ray (HXR) cluster emission by modeling the thermal contribution from the cluster gas and the nonthermal contamination from the unobscured active galactic nuclei (AGNs) in the clusters. We also evaluate the systematic uncertainties due to the background fluctuations. Assuming negligible contamination from the obscured AGNs, the resulting nonthermal component is detected at a 2 sigma level in approx. 50% of the nonsignificantly AGN-contaminated clusters: A2142, A2199, A2256, A3376, Coma, Ophiuchus, and Virgo. The data are consistent with a scenario whereby relaxed clusters have no hard X-ray component of nonthermal origin, whereas merger clusters do, with a 20-80 keV luminosity of approx. 10(exp 43)-10(exp 44) h(sup -2 sub 50) ergs/s. The co-added spectrum of the above clusters indicates a power-law spectrum for the HXR emission with a photon index of 2.8(sup +0.3 sub -0.4) in the 12-115 keV band, and we find indication that it has extended distribution. These indications argue against significant contamination from obscured AGNs, which have harder spectra and a centrally concentrated distribution. These results are supportive of the assumption of the merger shock acceleration of electrons in clusters, which has been proposed as a possible origin of the nonthermal hard X-ray emission models. Assuming that the cosmic microwave background photons experience inverse Compton scattering from the merger-accelerated relativistic electrons and thus produce the observed HXR, the measured hard X-ray slope corresponds to a differential momentum spectra of the relativistic electrons with a slope of mu = 3.8-5.0. In presence of cluster magnetic fields this relativistic electron population produces synchrotron emission with a spectral index of 1.4-2.1, consistent with radio halo observations of merger clusters. Thus both hard X-ray and radio observations of merger clusters are consistent with the inverse Compton model.

Nevalainen, J.↗
NASA NTRS2010

PDS Lunar Data Node Restoration of Apollo In-Situ Surface Data

The Apollo missions between 1969 and 1972 deployed scientific instruments on the Moon's surface which made in-situ measurements of the lunar environment. Apollo II had the short-term Early Apollo Surface Experiments Package (EASEP) and Apollos 12, 14, 15, 16, and 17 each set up an Apollo Lunar Surface Experiments Package (ALSEP). Each ALSEP package contained a different suite of instruments which took measurements and radioed the results back to Earth over periods from 5 to 7 years until they were turned off on 30 September 1977. To this day the ALSEP data remain the only long-term in-situ information on the Moon's surface environment. The Lunar Data Node (LDN) has been formed under the auspices of the Planetary Data System (PDS) Geosciences Node to put relevant, scientifically important Apollo data into accessible digital form for use by researchers and mission planners. We will report on progress made since last year and plans for future data restorations.

Williams, David R.↗
NASA NTRS2012

Restoration of APOLLO Data by the NSSDC and PDS Lunar Data Node

The Apollo Lunar Surface Experiment Packages (ALSEPs), suites of instruments deployed by the Apollo 12. 14, 15, 16 and 17 astronauts on the lunar surface, still represent the only in-situ measurements of the Moon's environment taken over long time periods, Much of these data are housed at the National Space Science Data Center (NSSDC) at Goddard Space Flight Center but are in forms that are not readily usable, such as microfilm, hardcopy, and magnetic tapes with older, obsolete formats. The Lunar Data Node (LDN) has been formed under the auspices of the Planetary Data System (PDS) Geosciences Node to put relevant, scientifically important Apollo data into accessible digital form for use by researchers and mission planners. The LDN has prioritized the restoration of these data based on their scientific and engineering value and the level of effort required. We will report on progress made and plans for future data restorations.

Williams, David R.↗
NASA NTRS2012

User Guide to the PDS Dataset for the Cassini Composite Infrared Spectrometer (CIRS)

This User Guide to the Cassini Composite Infrared Spectrometer (CIRS) has been written with two communities in mind. First and foremost, scientists external to the Cassini Project who seek to use the CIRS data as archived in the Planetary Data System (PDS). In addition, it is intended to be a comprehensive reference guide for those internal to the CIRS team.

Nixon, Conor A.↗
NASA NTRS2018

Differences in the Gas and Dust Distribution in the Transitional Disk of a Sun-Like Young Star, PDS 70

We present ALMA 0.87 mm continuum, HCO+ J = 4–3 emission line, and CO J = 3–2 emission line data of the disk of material around the young, Sun-like star PDS 70. These data reveal the existence of a possible two-component transitional disk system with a radial dust gap of 0.42 arcsec ± 0.05 arcsec, an azimuthal gap in the HCO+ J = 4–3 moment zero map, as well as two bridge-like features in the gas data. Interestingly these features in the gas disk have no analog in the dust disk making them of particular interest. We modeled the dust disk using the Monte Carlo radiative transfer code HOCHUNK3D using a two-disk component. We find that there is a radial gap that extends from 15 to 60 au in all grain sizes, which differs from previous work.

radial gap↗
NASA NTRS1975

Detailed requirements document for the problem reporting data system (PDS)

The system is described as a computer-based system designed to track the status of problems and corrective actions pertinent to space shuttle hardware. The input, processing, output, and performance requirements of the system are presented along with standard display formats and examples. Operational requirements, hardware, requirements, and test requirements are also included.

West, R. S.↗
NASA NTRS1984

Performance testing of the high altitude observatory PDS microdensitometer

High Altitude Observatory HAO microdensitometer undergoes monthly testing to assure its consistent performance. These tests check positional and photometric stability at the 10 micron aperture level. The HAO test procedure is designed to run without operator intervention following initial configuration of the microdensitometer for each subprocedure. Specialized test software is resident in the PDP 8. The operator selects the proper subprocedure by entering commands. Once computer control is established, it is not relinquished until the test is complete.

Poland, A.↗
NASA NTRS1984

The preparation of the measurements at the PDS at the Padova Observatory: Report on an experience with the development of an astronomical data base environment

Some software facilities used mainly for information retrieval and analysis at the Padova-Asiago Observatory are discussed. These facilities help guest and resident astronomers to make easier the preparation of plate measurements. The problems connected with the creation, use and management of a data base in a scientific (astronomical) environment are reviewed on the basis of the experience gathered during the last three years. The development plan of the user session environment and its possible applications in a computer network are briefly sketched.

Benacchio, L.↗
NASA NTRS1984

Astrometric applications of the Mt. Stromlo PDS 1010A

Problems in photographic astrometry to which the Mt. Stromlo (VA) microdensitometer is applied are described. It is used for measuring southern parallax region plates to determine photographic positions of the brighter satellites of the outer planets. Tests of the overall astrometric accuracy and stability of the machine, as well as results, show micron-level pecularities, but overall a quite satisfactory level of performance for the system.

Ianna, P. A.↗