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At least 163 records · Page 9

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NASA NTRS1977

Viking Radio Occultation Measurements of the Martian Atmosphere and Topography: Primary Mission Coverage

Radio occultation measurements were made at approximately 50 locations on Mars with the Viking Orbiter 1 S (2.3 GHz) and X (8.4 GHz) band tracking links during October 1976. The measurements have been used to study the topography and atmosphere of Mars at latitudes ranging from about 75 deg S to 70 deg N. By using the ingress and egress times obtained from the observed limb diffraction effects together with the best ephemerides available for the orbiter and the planet we have determined the surface elevations at the occultation points relative to the reference areoid. The observations agree with Mariner 9 and radar data to within 2 km. The mean atmospheric pressure at the areoid level was found to be 5.9 mbar during the northern midsummer season, a value which agrees quite well with data obtained at the landing sites. By comparing the new electron density measurements with earlier Mariner data we have determined that the temperature and the plasma scale height of the upper atmosphere appear to be functions of solar activity.

Fjeldbo, G.↗

NASA NTRS1977

Origin and relative age of lunar and Mercurian intercrater plains

Differences in the diameter/density distribution of craters in the size range 7-100 km between heavily cratered areas and areas of intercrater plains indicate the deposition of both lunar and Mercurian intercrater plains has preferentially obliterated craters not greater than about 30 km diameter. This obliteration has altered the original lunar population distribution function from about a -1.3 slope to about -0.7 slope. At least a significant portion of both the lunar and Mercurian intercrater plains appear to be volcanic deposits emplaced during the later stages of heavy bombardment on each body rather than basin ejecta or an ancient primordial surface. The very widespread distribution of intercrater plains on Mercury compared to the moon may be related to Mercury's core formation which would have resulted in a large radius increase leading to widespread extensional fracturing to provide egress for the eruption of volcanic deposits on a global scale. This was followed by a radius decrease due to contraction of the lithosphere to produce thrust faulting represented by Mercury's lobate scarps.

Strom, R. G.↗

NASA NTRS1978

Rotor Systems Research Aircraft /RSRA/ Emergency Escape System

The three-man Rotor Systems Research Aircraft (RSRA) Emergency Escape System, the first system known to be fully qualified and operational in a rotary wing aircraft, will have two modes of operation: one providing for full in-flight egress, and the other for the severance of the rotor blades for a return to base as a fixed-wing aircraft. This paper describes the escape system's design principles, integration into the aircraft, qualification, and performance.

Bement, L. J.↗

NASA NTRS1979

Helicopter emergency escape

Bement, L. J.↗

NASA NTRS1979

Viking radio occultation measurements of the atmosphere and topography of Mars - Data acquired during 1 Martian year of tracking

The results of one Martian year of radio occultation measurements of the atmosphere and topography of Mars obtained using the Viking Orbiters are briefly summarized. Determinations of the vertical distribution of tropospheric gas refractivity and ionospheric electron density obtained from atmospheric Doppler frequency perturbations of the S and X band radio tracking frequencies indicate large meteorological variations, with near-surface temperatures ranging from 150 to 250 K, 5-km atmospheric pressure ranging from 3.5 to 4.8 mbar, inversion layers over the polar caps and dust storms, and seasonal pressure variations. Double- and single-layered upper atmospheric electron density profiles were observed on the sunlit and dark sides of the planet, respectively. A topographic map of the Martian surface, obtained from the limb diffraction effects observed at ingress and egress, is found to agree well with the elevation contours of US Geological survey map M 25M 3 RMC, with the exception of the south polar and Alba Patera regions.

Lindal, G. F.↗

NASA NTRS1981

Annual survey of spaceflight safety systems: 11th supplement. Survey period - July 1980-June 1981

Reports in the field of space flight safety applicable to current and future operational space activities which appeared between July 1980 and June 1981 are surveyed. Subjects in the area of flight rescue and safety during launch, on-orbit, reentry and landing phases include the major activities and findings of the first Shuttle test flight, a slidewire system for emergency egress from the Space Shuttle on the launch pad, and the testing of the Spacelab engineering model. In the area of human capabilities and crew roles, attention is given to reports of repairs to the Salyut 6 space station made by a Soyuz crew, and an assessment of weightlessness effects on space worker health and safety. Safety requirements for STS payloads including pressure vessels, and the Orbiter window system and for spacecraft testing are also presented, along with those for a television system to aid in monitoring astronaut extravehicular activities. For the operation of large space structures, reports include EVA equipment for satellite servicing and the safety aspects of connectors used in construction. Finally, attention is given to safety-related criteria in a study of Shuttle interactions with the proposed Space Operations Center.

Brown, N. E.↗

NASA NTRS1982

An ultraviolet investigation of the unusual eclipsing binary system FF AQR

A series of seven low dispersion IUE exposures in ultraviolet and wavelength regions obtained on December 6, 1981 during the eclipse of the subdwarf, during egress, and out of eclipse is analyzed. These observations and the binary phase at which they were made are shown on a schematic representation of the V-band light curve obtained in 1975. The depth in V is 0.15 mag. The circles are IUE V magnitudes from FES measures obtained during the observing run. They indicate an eclipse depth some 0.05 mag lower than expected, possibly due to difficulties with the color term in the FES calibration. The eclipse depths of Dworetsky in U, B and V were assumed in the calculations.

Dorren, J. D.↗

NASA NTRS1984

Safe Emergency Evacuation From Tall Structures

Emergency egress system allows people to be evacuated quickly from tall structures. New emergency system applicable to rescues from fires in tall hotels and other buildings. System consists of basket on slide wire. Basket descends by gravity on sloped slide wire staked to ground.

Stephan, E. S.↗

NASA NTRS1982

Optimization of fire blocking layers for aircraft seating

Ablative materials are used to provide thermal protection for heat sensitive substrates against large jet fuel fires. The present investigation is concerned with the possibility to increase the available egress time for passengers, from a transport aircraft, in which the flexible polyurethane seating is exposed to the action of a large pool fire. Suitable approaches for providing sufficient ablative protection for polyurethane cushioning are considered. The efficiency of any fire blocking layer is defined as the ratio of the incident radiant heating rate, to the rate of production of combustible gas produced per unit area per second, generated by the pyrolysis of the substrate polyurethane foam. It is found that adequate fire blocking protection can be achieved through replacement of cotton batting slip covers with a wide variety of fire blocking layers. Metallized high temperature resistant char forming ablatives appear to provide optimum protection.

Parker, J. A.↗

NASA NTRS1984

Field repair of AH-16 helicopter window cutting assemblies

The U.S. Army uses explosively actuated window cutting assemblies to provide emergency crew ground egress. Gaps between the system's explosive cords and acrylic windows caused a concern about functional reliability for a fleet of several hundred aircraft. A field repair method, using room temperature vulcanizing silicone compound (RTV), was developed and demonstrated to fill gaps as large as 0.250 inch.

Bement, L. J.↗

NASA NTRS1983

Infrared observations of RS CVn stars

The paper presents infrared photometry of the RS CVn binary stars AR Lac (1.2-10 microns) and MM Her (1.2-3.5 microns) as they egressed from their primary and secondary eclipses; of the eclipsing systems RS CVn and Z Her at maximum light (1.2-10 microns) and of the non-eclipsing systems UX Ari and HR 1099 (1.2-10 microns). An analysis of these and published V data based on flux ratio diagrams (linear analogues of color-color diagrams) shows that G and K stars supply the infrared light of these systems. In AR Lac, the combined light of a G5-K0 subgiant and either a late F dwarf or an early F subgiant can account for the observed visual and infrared light curves. None of these systems shows infrared emission from circumstellar matter. This result is simply understood: dust grains would not be expected to form in the physical conditions surrounding the subgiant, and the corona and chromosphere (whose properties have been deduced from spectroscopic X-ray observations) should not produce appreciable infrared emission.

Berriman, G.↗

NASA NTRS1983

A basic design fault in ceramic flat packs

Drotman, B.↗

NASA NTRS1983

A basic design fault in ceramic flat packs

Recent moisture resistance tests of various multilayer top brazed ceramic flat packs and leaded and unleaded chip carriers has revealed a serious design defect. These packages, which utilize a tungsten interconnect system, in the presence of high humidity, suffer a galvanic corrosion which anodically consumes the tungsten. This process can continue until the package suffers an open circuit. The test results indicate that the lead plating system does not adequately seal off the interface area where the tungsten stripe egresses from the inside of the package. Leaded and leadless chip carrier packages were also subjected to the moisture resistance test. The familiar red and green corrosion products were visible after the test was completed. Careful sectioning of the chip carriers has revealed that the tungsten interconnect stripe instead of exiting under the castellations, exits at the top of the castellation and is thus vulnerable to the attack of moisture. These basic design faults severely impact the reliability of these packages.

Drotman, B.↗

NASA NTRS1984

PG 1012-029 - A high-excitation eclipsing cataclysmic variable

The paper presents a photometric and spectrophotometric analysis of a new eclipsing cataclysmic variable, PG 1012-029, with an orbital period of 3 hr 14 minutes 18.7 s. The eclipse depth reaches 1.9 mag, is rounded at minimum, and shows a prolonged egress 'shoulder', as found for UX UMa and some other eclipsing systems. The spectrum shows strong high-excitation lines at optical and UV wavelengths. A large fraction of the He II flux disappears during the eclipse, when the hydrogen spectrum fits a cooler temperature, and the continuum reddens. This behavior is attributed to eclipse of the hotter inner disk region.

Penning, W. R.↗

NASA NTRS1985

Study of several factors affecting crew escape trajectories from the Space Shuttle Orbiter at low-subsonic speeds

Factors affecting the bailout characteristics from the space shuttle orbiter at low-subsonic speeds were investigated. In the 12-foot low-speed tunnel and the 4 by 7-meter tunnel with 0.03-scale models. The effect of crew-model exit velocity, body position, and body weight were studied with egress from the main side hatch with the orbiter upright and from the upper cabin hatch with the orbiter inverted. Crew model drag and flow field measurements around the orbiter were estimated. The high-angle-of-attack trim characteristics of the orbiter was determined by force tests in an attempt to improve bailout conditions. A computer simulation was made to evaluate the maneuver necessary to attain the high-angle-of-attack trim.

Scallion, W. I.↗

NASA NTRS1985

Optical photometry of the 1982-1984 eclipse of Epsilon Aurigae

From slightly before the 1982-1984 eclipse of Epsilon Aurigae to the present observers from around the world have been making photoelectric photometry observations of this star system. Over 2000 UBV observations have been reported as well as observations in the R, I, J, H, K, L, M, N, and Q bandpasses plus the y, b, v, and u bandpasses. Twenty nine observers from 9 countries submitted photometry data to the campaign. The data have shown many interesting features of the star system including a Cepheid-like pulsation, flare activity, mid-eclipse brightening, post egress brightening, plus other strange activity.

Hopkins, J. L.↗

NASA NTRS1985

Advanced emergency openings for commercial aircraft

Explosively actuated openings in composite panels are proposed to enhance passenger survivability within commercial aircraft by providing improvements in emergency openings, fuselage venting, and fuel dump. The concept is to embed a tiny, highly stable explosive cord in the periphery of a load-carrying composite panel; on initiation of the cord, the panel is fractured to create a well-defined opening. The panel would be installed in the sides of the fuselage for passenger egress, in the top of the fuselage for smoke venting, and in the bottoms of the fuel cells for fuel dump. Described are the concerns with the use of explosive systems, safety improvements, advantages, experimental results, and recommended approach to gain acceptance and develop this concept.

Bement, L. J.↗

NASA NTRS1985

The August 1984 eclipse of 22 Vulpeculae

Observations are reported of the newly discovered eclipsing binary 22 Vul (G3 IB-II+B9), in and around the 1984 eclipse. IUE satellite and ground-based photometric observations are included. The depth of total eclipse of the hot component was 0.05 mag in the V band, 0.14 in B, and 0.35 in U. Time of mideclipse is now established at JD1445942.3 (1984 August 29.8) plus-or-minus 0.2 day, with an eclipse duration of 9.8 plus-or-minus 0.2 days. The period is 249.115 plus-or-minus 0.024 days. The ingress and egress phases, lasting only about one day in visible light, last a week or more at some UV wavelengths and are not symmetrical.

Parsons, S. B.↗