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At least 1,063 records · Page 59

The NOL ballistic piston compressor 2: Operation up to 5,000 ATM

Experiments are described which demonstrated the feasibility of rapidly compressing inert gases in a ballistic piston compressor to simultaneously high temperatures and densities previously unobtainable in the laboratory. With argon, temperatures of the order of 6000 K and accompanying densities of the order of 100 Amagats have been obtained; and with nitrogen, temperatures and densities of 3000 K and 400 Amagats have been approached. Details of the design, assembly, instrumentation, and operating procedures are presented, and the results of mechanical and thermal performance tests up to 5000 atmospheres pressure are described. Emphasis is placed on experiments which demonstrated the usefulness of this apparatus for spectral line broadening studies.

Hammond, G. L.↗

Automated space processing payloads study. Volume 2, book 2: Technical report, appendices A through E

Experiment hardware and operational requirements for space shuttle experiments are discussed along with payload and system concepts. Appendixes are included in which experiment data sheets, chamber environmental control and monitoring, method for collection and storage of electrophoretically-separated samples, preliminary thermal evaluation of electromagnetic levitation facilities L1, L2, and L3, and applicable industrial automation equipment are discussed.

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Objective techniques for psychological assessment, phase 2

Results are presented of an initial experiment in a research program designed to develop objective techniques for psychological assessment of individuals and groups participating in long-duration space flights. Specifically examined is the rationale for utilizing measures of attention as an objective assessment technique. Subjects participating in the experiment performed various tasks (eg, playing matrix games which appeared on a display screen along with auditory stimuli). The psychophysiological reactions of the subjects were measured and are given. Previous research of various performance and psychophysiological methods of measuring attention is also discussed. The experiment design (independent and dependent variables) and apparatus (computers and display devices) are described and shown. Conclusions and recommendations are presented.

Wortz, E. C.↗

Tidal evolution of the Uranian satellites. III - Evolution through the Miranda-Umbriel 3:1, Miranda-Ariel 5:3, and Ariel-Umbriel 2:1 mean-motion commensurabilities

Numerical experiments have been conducted which indicate that the orbital eccentricity of Miranda may have reached a value sufficiently large to have affected its thermal evolution. There is a large chaotic zone associated with the Miranda-Ariel 5:3 mean-motion commensurability, even in the planar approximation; the orbital eccentricities of both satellites may vary chaotically for a considerable period. Since the anomalously high orbital inclination of Miranda is a consequence of passage through the 3:1 commensurability with Umbriel, the requirement that the satellites encountered this resonance places a lower limit on the Uranian specific dissipation function of 39,000.

Tittemore, William C.↗

PULSAUR 2

PULSAUR II is a sounding rocket experiment to investigate the pulsating aurora and related phenomena. The payload consists of a complementary set of instruments designed specifically to look at the pulsating aurora. The project will be managed by the Norwegian Space Center, with integration in Norway. The rocket is due for launch in January 1994 from the Andoya rocket range. Southwest Research Institute provided an electron sensor for this campaign. It is a 'top hat' electron spectrometer, referred to as AREA (Angle Resolving Energy Analyzer), and is based on the electron sensor developed for the CENTAUR mission.

Sharber, Jim↗

Environment modelling in near Earth space: Preliminary LDEF results

Hypervelocity impacts by space debris cause not only local cratering or penetrations, but also cause large areas of damage in coated, painted or laminated surfaces. Features examined in these analyses display interesting morphological characteristics, commonly exhibiting a concentric ringed appearance. Virtually all features greater than 0.2 mm in diameter possess a spall zone in which all of the paint was removed from the aluminum surface. These spall zones vary in size from approximately 2 - 5 crater diameters. The actual craters in the aluminum substrate vary from central pits without raised rims, to morphologies more typical of craters formed in aluminum under hypervelocity laboratory conditions for the larger features. Most features also possess what is referred to as a 'shock zone' as well. These zones vary in size from approximately 1 - 20 crater diameters. In most cases, only the outer-most layer of paint was affected by this impact related phenomenon. Several impacts possess ridge-like structures encircling the area in which this outer-most paint layer was removed. In many ways, such features resemble the lunar impact basins, but on an extremely reduced scale. Overall, there were no noticeable penetrations, bulges or spallation features on the backside of the tray. On Row 12, approximately 85 degrees from the leading edge (RAM direction), there was approximately one impact per 15 cm(exp 2). On the trailing edge, there was approximately one impact per 72 cm(exp 2). Currently, craters on four aluminum experiment trays from Bay E09, directly on the leading edge are being measured and analyzed. Preliminary results have produced more than 2200 craters on approximately 1500 cm(exp 2) - or approximately 1 impact per 0.7 cm(exp 2).

Coombs, C. R.↗

Nighttime/daytime optical survey of lightning and convective phenomena experiment (NOSL)

The Nighttime/Daytime Optical Survey of Lightning experiment was selected for flight on Orbital Flight Test 2 of the Space Shuttle. The background and rationale for the experiment are presented and the experiment hardware, the operating procedures, and the data analysis technique are discussed. Some preliminary results from the prototype hardware development are also presented.

Vonnegut, B.↗

Improved silicon carbide for advanced heat engines

This is the third annual technical report for the program entitled, Improved Silicon Carbide for Advanced Heat Engines, for the period February 16, 1987 to February 15, 1988. The objective of the original program was the development of high strength, high reliability silicon carbide parts with complex shapes suitable for use in advanced heat engines. Injection molding is the forming method selected for the program because it is capable of forming complex parts adaptable for mass production on an economically sound basis. The goals of the revised program are to reach a Weibull characteristic strength of 550 MPa (80 ksi) and a Weibull modulus of 16 for bars tested in 4-point loading. Two tasks are discussed: Task 1 which involves materials and process improvements, and Task 2 which is a MOR bar matrix to improve strength and reliability. Many statistically designed experiments were completed under task 1 which improved the composition of the batches, the mixing of the powders, the sinter and anneal cycles. The best results were obtained by an attritor mixing process which yielded strengths in excess of 550 MPa (80 ksi) and an individual Weibull modulus of 16.8 for a 9-sample group. Strengths measured at 1200 and 1400 C were equal to the room temperature strength. Annealing of machined test bars significantly improved the strength. Molding yields were measured and flaw distributions were observed to follow a Poisson process. The second iteration of the Task 2 matrix experiment is described.

Whalen, Thomas J.↗

On the nature of two gamma bursts with spectral evolutions observed by the KONUS experiment

Several unique features of the evolving spectra of the April 2, 1979B, and November 11, 1979 gamma-ray bursts observed by the Konus experiment can be used to determine a number of critical parameters of the sources, within the context of the thermal synchrotron model, including their luminosity distance. These results shed much light on the origin of these events and possibly gamma bursts in general. Previously announced in STAR as N83-14057

Liang, E. P.↗

Using Computer Simulation for Neurolab 2 Mission Planning

This paper presents an overview of the procedure used in the creation of a computer simulation video generated by the Graphics Research and Analysis Facility at NASA/Johnson Space Center. The simulation was preceded by an analysis of anthropometric characteristics of crew members and workspace requirements for 13 experiments to be conducted on Neurolab 2 which is dedicated to neuroscience and behavioral research. Neurolab 2 is being carried out as a partnership among national domestic research institutes and international space agencies. The video is a tour of the Spacelab module as it will be configured for STS-90, scheduled for launch in the spring of 1998, and identifies experiments that can be conducted in parallel during that mission. Therefore, this paper will also address methods for using computer modeling to facilitate the mission planning activity.

Sanders, Betty M.↗

Fleet retrofit report

Flight tests are evaluated of an avionics system which aids the pilot in making two-segment approaches for noise abatement. The implications are discussed of equipping United's fleet of Boeing 727-200 aircraft with two-segment avionics for use down to Category 2 weather operating minima. The experience is reported of incorporating two-segment approach avionics systems on two different aircraft. The cost of installing dual two-segment approach systems is estimated to be $37,015 per aircraft, including parts, labor, and spares. This is based on the assumption that incremental out-of-service and training costs could be minimized by incorporating the system at airframe overhaul cycle and including training in regular recurrent training. Accelerating the modification schedule could add up to 50 percent to the modification costs. Recurring costs of maintenance of the installation are estimated to be of about the same magnitude as the potential recurrent financial benefits due to fuel savings.

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Space calibration of standard solar cells using high altitude sounding rockets

Four photovoltaic cells were space calibrated and successfully recovered from a NASA Aerobee rocket launched on Sept. 18, 1974, which reached a peak altitude of 251 km. The experiment was comprised of four 2 ohm-cm n/p cells, two of which are optically filtered with 0.6 to 0.9 micron bandpass filters. The short-circuit current agreed to within 4% of the laboratory calibration. The variation of cell output due to atmospheric attenuation between the altitude range 80 and 251 km was 0.4% for the unfiltered cells.

Thomas, N. L.↗

Probing the earth's gravity field by means of satellite-to-satellite tracking

Two satellite-to-satellite tracking (sst) tests are described in detail: (1) the ATS-6/Geos-3 and (2) the ATS-6/Apollo-Soyuz experiment. The main purpose of these two experiments was to track via ATS-6 the Geos-3, as well as the Apollo-Soyuz and to use these tracking data to determine both of the orbits at the same time, each of the orbits alone, and to test the two sst links to study local gravity anomalies. A second purpose was to test communications, command and data transmission from the ground via ATS-6 to these spacecraft and back again to the ground.

Vonbun, F. O.↗

Indexing, screening, coding and cataloging of earth resources aircraft mission data

Tasks completed are as follows: (1) preparation of large Area Crop Inventory experiment for data base entry;(2) preparation of Earth Observations Aircraft Flight summary reports for publication; (3) updating of the aircraft mission index coverage map and Ames aircraft flight map; (4) Prepared of Earth Observation Helicopter Flight reports for publication; and (5) indexing of LANDSAT imagery. (6) formulation of phase 3 biowindows 1, 2, 3, and 4 listings by country, footprint, and acqusition dates; (7) preparation of flight summary reports; and (8) preparation of an Alaska state index coverage map.

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Energetic plasma ions within the earth's magnetosheath

Observations in the dawn magnetosheath with the LASL/MPI fast plasma experiment on ISEE 1 and 2 reveal the existence of two distinct states of plasma flow within the sheath: a quiet state and a disturbed state. Energetic ions in the range of 3-40 keV are the distinguishing feature of the disturbed state. Long period (about 1 min) fluctuations in plasma density, temperature, flow speed, and flow direction occur simultaneously with the appearance of these high-energy particles. The most likely explanation of these observations is that the energetic ions are produced in the vicinity of the bow shock under certain (unspecified) interplanetary conditions, and that the fluctuations in plasma flow are produced locally by the interaction of the energetic ions with the ambient plasma.

Asbridge, J. R.↗