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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 109 records · Page 6
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NASA NTRS1973

Mariner 9 ultraviolet spectrometer experiment: Seasonal variation of ozone on Mars

On Mars, the Mariner observations show a twenty-fold variation in the amount of ozone, depending on the presence or absence of another minor constituent, water vapor, in the atmosphere. In the evolution of earth's primitive atmosphere, the formation of an ozone layer may have played an important role in the prebiotic chemistry that took place on the surface. The seasonal formation and disappearance of ozone in the contemporary Martian atmosphere may be of consequence in any prebiotic chemistry that may be occurring there.

Barth, C. A.↗
NASA NTRS1973

Ultraviolet spectrometer experiment

The original scientific objectives and the achieved results are discussed. The upper atmosphere was found to have a variable temperature, with a mean exospheric temperature of 325 K; composed predominantley of CO2. Measurements of hydrogen and ozone are analyzed.

Barth, C. A.↗
NASA NTRS1972

Mariner 9 ultraviolet spectrometer experiment - Photometry and topography of Mars.

Reflectance properties of Mars were measured in a 100-A band (centered at 3050 A) by the UV spectrometer on board Mariner 9 during the period from Nov. 14, 1971 to Mar. 1, 1972. A topographic map of Mars based on the scattering of UV light from the Mars atmosphere (after clearing of the dust storm) is illustrated. The UV light which is Rayleigh-scattered by the Mars molecular atmosphere (with allowance for uniform turbidity) is proportional to surface pressure regardless of the atmospheric temperature structure. Comparison with Mariner 9 radio occultation measurements determines the fraction of total reflectance that is due to atmospheric scattering.

Hord, C. W.↗
NASA NTRS1972

Mariner 9 ultraviolet spectrometer experiment - Structure of Mars' upper atmosphere.

Mariner 9 observations of the limb intensity profile of the CO Cameron bands in the Martian airglow demonstrate the validity of a postulated relationship between the equivalent subsolar zenith intensity and the 10.7-cm solar radio flux. Comparison of averaged limb intensities of the CO2+ doublet and the Cameron bands on four favorable occasions is consistent with the intensities being directly proportional in a ratio of 0.24 to 1.

Stewart, A. I.↗
NASA NTRS1973

Mariner 9 ultraviolet spectrometer experiment - Seasonal variation of ozone on Mars.

Ozone is observed to be present in the polar regions of Mars and to have a seasonal variation. In the summer, the amount present in the polar atmosphere is less than 3 micrometer-atmospheres. In the fall, ozone increases in amount and is found in association with the formation of the polar hood. In winter, the maximum amount of ozone is present, 57 micrometer-atmospheres over the polar hood and 16 over the polar cap. In spring, the amount over the polar cap decreases monotonically until by the beginning of summer the ozone disappears. Ozone is not observed in the equatorial region during any season.

Barth, C. A.↗
NASA NTRS1973

Mariner 9 ultraviolet spectrometer experiment - Mars atomic oxygen 1304-A emission.

Selected results are presented for an analysis of Mariner 9 1304-A data from the first 100 passes. Based on a comparison of limb data, the exospheric temperature appears lower on several Mariner 9 passes than when Mariner 6 and 7 encountered the planet in 1969. Temperatures of 300 and 350 K are considered in the atmospheric modeling. At 300 K, derived values of the atomic oxygen concentration are typically between 0.5 and 1% of the total density at 135 km, based on fitting theoretical intensities to limb data from several passes. Structure in the limb data below 200 km suggests the possibility that approximately 0.2 kR of the observed approximately 0.8 kR near 150 km is due to dissociative excitation of CO2. There is variability in limb profiles, thus indicating changes in the O distribution with time. The variability does not appear to follow a recognizable pattern. Interpretation of the 1304-A disk data shows a correlation in intensity with the 10.7-cm solar flux and larger O concentrations in the afternoon than in the morning. The correlation in intensity with the 10.7-cm flux is probably due largely to variation in the solar 1304-A fluxes.

Strickland, D. J.↗
NASA NTRS1973

Mariner 9 ultraviolet spectrometer experiment - 1971 Mars' dust storm.

The brightness of a region on the south polar cap centered at approximately -87 deg S, 10 deg W was observed. Measurements taken at various incidence and emission angles show that the brightness increased with decreasing air mass. The observed intensity consists primarily of a component reflected from the cap and twice attenuated by the atmosphere and a component diffusely reflected from the atmosphere. The dust cloud over the polar cap was moderately thick between Nov. 26 and Dec. 2, 1971. At this time the optical thickness was near unity, and it decreased approximately linearly with time, reaching a value close to that of a Rayleigh atmosphere by mid-February. The optical thickness showed little dependence on the wavelength during the early orbital observations.

Pang, K.↗
NASA NTRS1974

Extreme ultraviolet spectrometer for space research

A normal incidence spectrometer for use in the wavelength region from 200 to 1270 A has been developed. The design and calibration of the instrument are described in detail. The spectrometer can be employed to detect extreme UV radiation at a minimum flux level of 1 rayleigh with a spectral resolution of 40 A and a spatial resolution of 6 deg. Data on the extreme UV night sky spectrum between 780 and 1270 A obtained with this instrument on a recent rocket flight are presented.

Kumar, S.↗
NASA NTRS1975

Mariner 9 ultraviolet spectrometer experiment - Scattering properties of Hellas

A least-squares analysis of 709 Mariner 9 UV spectra obtained over Hellas from Revolution 140 to 214 (Jan. 22, 1972, to Feb. 28, 1972) showed the extinction optical depth of the atmosphere above Hellas to be 0.5 plus or minus 0.2. This is evidence of lingering dust in the Hellas basin. An atmospheric model, combining dust and Rayleigh scattering, was used to make an apparent pressure map of Hellas. Anomalously high pressures are interpreted as clouds developing over the southern part of Hellas near the time of autumnal equinox. The blue ratio (reflectance at 2680 A divided by reflectance at 3050 A) showed a 20% increase from Revolution 40 to Revolution 74, attributed to the decay of the dust storm. Thereafter, the blue ratio remained essentially constant through Revolution 214, which implies that the rate of clearing in Hellas was much slower than that planetwide.

Ajello, J. M.↗
NASA NTRS1981

Performance and design of the ultraviolet spectrometer and polarimeter on the solar maximum mission

The instrument observes spectral line intensity, Doppler motions, and polarization parameters. First Dopplergrams of the sun showing mass motion of prominences have been obtained. The instrument consists of a telescope, a spectrometer, a polarimeter, and five detectors. Spectral range extends from 1150 to 3600 Angstroms. The telescope is an alphanatic Gregorian capable of scanning a 256 x 256 arcsecond raster. The spectrometer is an Ebert-Fastie mount with exchangeable slits for intensity measurements and spectroscopy. Detectors are photomultipliers operating in the pulse-counting mode.

Sterk, A. A.↗
NASA NTRS1980

Orbiting solar observatory 8 high resolution ultraviolet spectrometer experiment

Oscillations, physical properties of the solar atmosphere, motions in the quiet solar atmosphere, coronal holes, motions in solar active regions, solar flares, the structure of plage regions, an atlas, and aeronomy are summarized. Photometric sensitivity, scattered light, ghosts, focus and spectral resolution, wavelength drive, photometric sensitivity, and scattered light, are also summarized. Experiments are described according to spacecraft made and experiment type. Some of the most useful data reduction programs are described.

Source record↗
NASA NTRS1982

Measurements of solar transition zone velocities and line broadening using the ultraviolet spectrometer and polarimeter on the Solar Maximum Mission

The UVSP instrument on SMM is able to observe solar regions at two wavelengths in the same line with a band-pass of 0.3 A. Intensity and Doppler velocity maps are derived. It is shown that the numerical values are sensitive to the adopted Doppler width and the range of velocities is limited to within 30 km/sec. A method called Double Dopplergram Determination (DDD) is described for deriving both the Doppler width and the velocity (up to 80 km/sec), and the main sources of uncertainties are discussed. To illustrate the method, a set of C IV 1548 A observations is analyzed according to this procedure. The mean C IV Doppler width measured (0.15 A) is comparable to previous determinations. A relation is found between bright regions and down-flows. Large Doppler widths correspond to strong velocity gradients.

Simon, G.↗
NASA NTRS1986

Ultraviolet spectrometer observations of Uranus

The Voyager 2 UV spectrometer was used to scan the Uranus atmosphere at wavelengths from 500-1700 A with a field of view of 0.1 x 0.86 deg. The temperature and composition of the upper atmosphere were determined through occultations of light from gamma Pegasi, nu Geminorum and the sun. The data indicated a substantial gas density (100 million H atoms/cu cm) at about 28,000 km from the Uranus center, suggesting that gas drag plays a significant role in ring evolution. The distributions of CH4 and C2H2 in the lower atmosphere were also estimated. An electroglow emission was detected on the sunlit side, and attributed to emissions from atomic and molecular hydrogen excited by low energy electrons. An auroral glow was also observed, and exhibited evidence of an energy input equal to that of the electroglow. Finally, estimates of the C2H2 mixing ratio and the vertical column abundance of H2 are calculated.

Broadfoot, A. L.↗