2,932 research outputs found
Study of space battery accelerated testing techniques. Phase 1 report. Survey of testing methods applicable to space battery evaluation
Testing methods applicable to space battery evaluation - literature surve
Study of space battery accelerated testing techniques. Phase 2 report - Ideal approaches towards accelerated tests and analysis of data
Ideal approaches to accelerated life tests and data analysis applied to space batterie
Proceedings of the 1st Space Plasma Computer Analysis Network (SCAN) Workshop
The purpose of the workshop was to identify specific cooperative scientific study topics within the discipline of Ionosphere Magnetosphere Coupling processes and to develop methods and procedures to accomplish this cooperative research using SCAN facilities. Cooperative scientific research was initiated in the areas of polar cusp composition, O+ polar outflow, and magnetospheric boundary morphology studies and an approach using a common metafile structure was adopted to facilitate the exchange of data and plots between the various workshop participants. The advantages of in person versus remote workshops were discussed also
Evaluation of Skylab (EREP) data for forest and rangeland surveys
The author has identified the following significant results. Four widely separated sites (near Augusta, Georgia; Lead, South Dakota; Manitou, Colorado; and Redding, California) were selected as typical sites for forest inventory, forest stress, rangeland inventory, and atmospheric and solar measurements, respectively. Results indicated that Skylab S190B color photography is good for classification of Level 1 forest and nonforest land (90 to 95 percent correct) and could be used as a data base for sampling by small and medium scale photography using regression techniques. The accuracy of Level 2 forest and nonforest classes, however, varied from fair to poor. Results of plant community classification tests indicate that both visual and microdensitometric techniques can separate deciduous, conifirous, and grassland classes to the region level in the Ecoclass hierarchical classification system. There was no consistency in classifying tree categories at the series level by visual photointerpretation. The relationship between ground measurements and large scale photo measurements of foliar cover had a correlation coefficient of greater than 0.75. Some of the relationships, however, were site dependent
DE 1 RIMS operational characteristics
The Retarding Ion Mass Spectrometer (RIMS) on the Dynamics Explorer 1 spacecraft observes both the thermal and superthermal (50 eV) ions of the ionosphere and inner magnetosphere. It is capable of measuring the detailed species distribution function of these ions in many cases. It was equipped with an integral electrometer to permit in-flight calibration of the detector sensitivities and variations thereof. A guide to understanding the RIMS data set is given. The reduction process from count rates to physical quantities is discussed in some detail. The procedure used to establish in-flight calibration is described, and results of a comparison with densities from plasma wave measurements are provided. Finally, a discussion is provided of various anomalies in the data set, including changes of channeltron efficiency with time, spin modulation of the axial sensor heads, apparent potential differences between the sensor heads, and failures of the radial head retarding potential sweep and of the -Z axial head aperture plane bias. Studies of the RIMS data set should be conducted only with a thorough awareness of the material presented here, or in collaboration with one of the scientists actively involved with RIMS data analysis
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Titan Mare Explorer (TiME): first in situ exploration of an extraterrestrial sea
The lakes and seas of Titan are a sink of products of photolysis in the atmosphere, and a crucial component in Titan's active methane cycle. In situ exploration of the seas is necessary to understand their intriguing prebiotic organic chemistry
Particle tracking in a salinity gradient: A method for measuring sinking rate of individual phytoplankton in the laboratory
This paper presents a new method to measure the sinking rates of individual phytoplankton “particles” (cells, chains, colonies, and aggregates) in the laboratory. Conventional particle tracking and high resolution video imaging were used to measure particle sinking rates and particle size. The stabilizing force of a very mild linear salinity gradient (1 ppt over 15 cm) prevented the formation of convection currents in the laboratory settling chamber. Whereas bulk settling methods such as SETCOL provide a single value of sinking rate for a population, this method allows the measurement of sinking rate and particle size for a large number of individual particles or phytoplankton within a population. The method has applications where sinking rates vary within a population, or where sinking rate-size relationships are important. Preliminary data from experiments with both laboratory and field samples of marine phytoplankton are presented here to illustrate the use of the technique, its applications, and limitations. Whereas this paper deals only with sinking phytoplankton, the method is equally valid for positively buoyant species, as well as nonbiological particles
A study of Jupiter's aurorae with XMM-Newton
We present a detailed analysis of Jupiter's X-ray (0.2-10 keV) auroral
emissions as observed by XMM-Newton in Nov. 2003 and compare it with that of an
Apr. 2003 observation. We discover the existence of an electron bremsstrahlung
component in the aurorae, which accounts for essentially all the X-ray flux
above 2 keV: its presence had been predicted but never detected for lack of
sensitivity of previous X-ray missions. This bremsstrahlung component varied
significantly in strength and spectral shape over the 3.5 days covered by the
Nov. 2003 observation, displaying substantial hardening of the spectrum with
increasing flux. This variability may be linked to the strong solar activity
taking place at the time, and may be induced by changes in the acceleration
mechanisms inside Jupiter's magnetosphere. As in Apr. 2003, the auroral spectra
below 2 keV are best fitted by a superposition of line emission most likely
originating from ion charge exchange, with OVII playing the dominant role. We
still cannot resolve conclusively the ion species responsible for the lowest
energy lines (around 0.3 keV), so the question of the origin of the ions
(magnetospheric or solar wind) is still open. It is conceivable that both
scenarios play a role in what is certainly a very complex planetary structure.
High resolution spectra of the whole planet obtained with the XMM-Newton RGS in
the range 0.5-1 keV clearly separate emission lines (mostly of Fe) originating
at low latitudes on Jupiter from the auroral lines due to O. These are shown to
possess very broad wings which imply velocities of ~5000 km/s. Such speeds are
consistent with the energies at which precipitating and charge exchanging O
ions are expected to be accelerated in Jupiter's magnetosphere. Overall we find
good agreement between our measurements and the predictions of recent models.Comment: 16 pages, 17 figures, to be published in 'Astronomy and Astrophysics
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