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NASA NTRS1976

The abundance of deuterium relative to hydrogen in interstellar space

Copernicus satellite observations of the deuterium and hydrogen Lyman lines in the lines of sight to mu COl, gamma-2 Vel, alpha Cru AB, and alpha Vir AB are reported. Together with previously published data for beta Cen A, the results yield a value N(D)/N(H) of approximately 0.000018 (m.e.) or a total deuterium mass portion of approximately 0.000025. Values for all stars with their error bars are contained within a band ranging from 0.25 to 2.0 times the quoted mean ratio. These limits are probably representative of the region within 200 pc of the sun. The results for these stars are essentially independent of assumptions about the Doppler parameter describing the formation of the lines, although this value can be derived from the observations. The results are consistent with a maximum temperature of 6000 K for the lines of sight studied.

York, D. G.↗

NASA NTRS1977

The ratio of deuterium to hydrogen in interstellar space. III - The lines of sight to Zeta Puppis and Gamma Cassiopeiae

An extensive set of measurements of the ratio of deuterium to hydrogen in the interstellar medium has been undertaken. The general observing program is described along with the data reduction techniques used to separate the complex deuterium and hydrogen profiles, and the results of the measurements for two stars, Zeta Pup and Gamma Cas. For Gamma Cas, log N(D)/N(H) is found to be approximately -4.8, in agreement with previous measurements. For Zeta Pup, a complicated structure of absorbing clouds in the interstellar medium is inferred. The best value of log N(D)/N(H) is about -4.6 for each of two components. One component is probably more complex than can be demonstrated directly at the resolution employed, and log N(D)N(H) could be -4.0 or larger in this component.

Vidal-Madjar, A.↗

NASA NTRS1978

Spectral irradiance standard for the ultraviolet - The deuterium lamp

A set of deuterium lamps is calibrated as spectral irradiance standards in the 200-350-nm spectral region utilizing both a high accuracy tungsten spectral irradiance standard and a newly developed argon mini-arc spectral radiance standard. The method which enables a transfer from a spectral radiance to a spectral irradiance standard is described. The following characteristics of the deuterium lamp irradiance standard are determined: sensitivity to alignment; dependence on input power and solid angle; reproducibility; and stability. The absolute spectral radiance is also measured in the 167-330-nm region. Based upon these measurements, values of the spectral irradiance below 200 nm are obtained through extrapolation.

Saunders, R. D.↗

NASA NTRS1978

On the abundance of deuterium in Jupiter's atmosphere

The ratio of deuterium to hydrogen in the Jovian atmosphere has been calculated using a new approach. D/C is obtained from weak lines of HD and CH4 in the visible region of the spectrum while C/H is derived from stronger methane and hydrogen absorptions near 1 micron. This technique permits minimization of the varying effects on line formation caused by scattering in the Jovian atmosphere while relying on absorption bands whose strengths have been measured in the laboratory. The result is a deuterium-to-hydrogen ratio of 2.3 + or - 1.1 times 10 to the -5th power, within the range of local interstellar values

Combes, M.↗

NASA NTRS1978

Ultraviolet observations of cool stars. VII - Local interstellar hydrogen and deuterium Lyman-alpha

High-resolution Copernicus spectra of Epsilon Eri and Epsilon Ind containing interstellar hydrogen and deuterium L-alpha absorption lines are presented, reduced, and analyzed. Parameters of the interstellar hydrogen and deuterium toward these two stars are derived independently, without any assumptions concerning the D/H ratio. Copernicus spectra of Alpha Aur and Alpha Cen A are reanalyzed, and limits on the D/H number-density ratio consistent with the data for all four stars are considered. A comparison of the present estimates for the parameters of the local interstellar medium with those obtained by other techniques shows that there is no compelling evidence for significant variations in the hydrogen density and D/H ratio in the local interstellar medium. On this basis the hypothesis of an approaching local interstellar cloud proposed by Vidal-Madjar et al. (1978) is rejected

Mcclintock, W.↗

NASA NTRS1979

The high-energy neutrino background - Limitations on models of deuterium production

It is pointed out that Epstein's (1977) model for deuterium production via high-energy spallation reactions produces high-energy neutrinos in sufficient quantity to stand out above those that are produced by cosmic-ray interactions in earth's atmosphere. That the Reines experiment detected neutrinos of atmospheric origin without detecting any cosmic component restricts deuterium production by spallation reactions to very high redshifts (z at least about 300). Improved neutrino experiments may be able to push these limits back to recombination.

Eichler, D.↗

NASA NTRS1979

The ratio of deuterium to hydrogen in interstellar space. IV - The lines of sight to Delta, Epsilon, and Iota Orionis

Deuterium absorption features in spectra of Delta, Epsilon, and Iota Ori obtained with Copernicus are analyzed. The Iota Ori line-of-sight analysis, which is quite detailed because of the high-velocity H I components superposed on the deuterium features, gives a D/H ratio (which is uncertain because of a complex profile) of 0.000014. A D/H ratio of the order of 7 millionths is determined for Delta and Epsilon Ori. For the complex line profiles involved, one may regard this as a formal lower limit. Several attempts were made to increase the ratio N(D I)/N(H I) in the context of reasonable models for the line of sight, but with no success; the derived values are therefore regarded as actual values, not lower limits. Since the derived value is an average on the line of sight, the possibility cannot be ruled out that the true ratios N(D I)/N(H I) in individual nearby components differ from the mean values. The mean value for these two directions is lower by a factor of 4 than the best value for the Zeta Pup line of sight (the highest yet derived for path lengths greater than 50 pc).

Laurent, C.↗

NASA NTRS1978

Thermal X-rays and deuterium production in stellar flares

The X-ray spectrum of flares is shown to be necessarily thermal up to at least 200 keV because the self-magnetic field of any electron stream required for a thick- or thin-target source is inconsistently large. The resulting flare model can then be related to stellar luminosity convection, and magnetic fields to result in a maximum possible gamma-burst and continuous X-ray flux. One of the most striking isotopic anomalies observed is the extreme enrichment of He-3 in some solar flares and the mysterious depletion of deuterium. The way in which deuterium may be produced and emitted in the largest flares associated with gamma-bursts but in amounts insufficient to support the tentative conclusion of Coleman and Worden (1976) is discussed.

Colgate, S. A.↗

NASA NTRS1982

Venus was wet - A measurement of the ratio of deuterium to hydrogen

The deuterium-hydrogen abundance ratio in the Venus atmosphere was measured while the inlets to the Pioneer Venus large probe mass spectrometer were coated with sulfuric acid from Venus' clouds. The ratio is 0.016 + or - 0.002. The hundredfold enrichment of deuterium means that at least 0.3 percent of a terrestrial ocean was outgassed on Venus, but is consistent with a much greater production.

Donahue, T. M.↗

NASA NTRS1984

Deuterium Abundance in the Local Interstellar Medium

The present situation of deuterium abundance evaluation in interstellar space is discussed, and it is shown that it should be or = .00001 by studying in more detail lambda the Sco line of sight and by observing two NaI interstellar components toward that star, it can be shown that the D/H evaluation made toward lambda Sco is in fact related to the local interstellar medium (less than 10 pc from the Sun). Because this evaluation is also or = .00001 it is in striking contrast with the one made toward alpha Aur (D/H or = .000018 confirming the fact that the deuterium abundance in the local interstellar medium varies by at least a factor of two over few parsecs.

Ferlet, R.↗

NASA NTRS1988

Deuterium on Mars - The abundance of HDO and the value of D/H

Deuterium on Mars has been detected by the resolution of several Doppler-shifted lines of HDO near 3.7 micrometers in the planet's spectrum. The ratio of deuterium to hydrogen is (9 + or - 4) x 10 to the -4th; the abundance of H2O was derived from lines near 1.1 micrometers. This ratio is enriched on Mars over the telluric value by a factor of 6 + or - 3. The enrichment implies that hydrogen escaped more rapidly from Mars in the past than it does now, consistent with a dense and warm ancient atmosphere on the planet.

Owen, Tobias↗

NASA NTRS1989

Deuterium content of the Venus atmosphere

The abundance of deuterium in the atmosphere of Venus is an important clue to the role of water in the planet's history, because ordinary and deuterated water escape the atmosphere at different rates. The high-resolution mode of the IUE was used to measure hydrogen Lyman-alpha emission from Venus, but only an upper limit on deuterium Lyman-alpha emission was found, from which was inferred a D/H ratio of less than 0.002-0.005. This is smaller by a factor of 3-8 than the D/H ratio derived from measurements by the Pioneer Venus Large Probe, and may indicate either a stratification of D/H ratio with altitude or a smaller overall ratio than previously thought.

Bertaux, Jean-Loup↗

NASA NTRS1989

Hydrogen and deuterium loss from the terrestrial atmosphere - A quantitative assessment of nonthermal escape fluxes

A comprehensive one-dimensional photochemical model extending from the middle atmosphere (50 km) to the exobase (432 km) has been used to study the escape of hydrogen and deuterium from the earth's atmosphere. The model incorporates recent advances in chemical kinetics as well as atmospheric observations by satellites, especially the Atmosphere Explorer C satellite. The results suggest that the escape fluxes of both H and D are limited by the upward transport of total hydrogen and total deuterium at the homopause. About one fourth of total hydrogen escape is thermal, the rest being nonthermal. It is shown that escape of D is nonthermal and that charge exchange and polar wind are important mechanisms for the nonthermal escape of H and D.

Yung, Yuk L.↗

NASA NTRS1990

Techniques for determining total body water using deuterium oxide

The measurement of total body water (TBW) is fundamental to the study of body fluid changes consequent to microgravity exposure or treatment with microgravity countermeasures. Often, the use of radioactive isotopes is prohibited for safety or other reasons. It was selected and implemented for use by some Johnson Space Center (JCS) laboratories, which permitted serial measurements over a 14 day period which was accurate enough to serve as a criterion method for validating new techniques. These requirements resulted in the selection of deuterium oxide dilution as the method of choice for TBW measurement. The development of this technique at JSC is reviewed. The recommended dosage, body fluid sampling techniques, and deuterium assay options are described.

Bishop, Phillip A.↗

NASA NTRS1992

Redistribution of Ti and Al in deuterium charged TiAl

The redistribution of titanium and aluminum in a single-phase TiAl alloy that has been exposed to a high pressure of deuterium gas at high temperature is studied. The microstructure in the as-received, uncharged condition consisted of single-phase gamma TiAl grains and a random distribution of precipitates. Precipitates were distributed throughout the matrix and along the grain boundaries. The chemistry of the precipitates varied considerably; some were rich in Al, while other were mostly Ti with some Si and Al. The dislocation density in most grains was low, although in a few grains a high dislocation density was observed. FCC deuterides with a lattice parameter of 0.45 nm form in a Ti-52.1Al-2.1Ta (at. pct) alloy after exposure to 1.38 MPa of deuterium gas at 650 C for 213 hr. The structure and lattice parameter are consistent with the formation of Ti(l)D2. The deuterides that form in this alloy are enriched in Ti and deficient in Al and Ta compared to the deuteride-free matrix. Regions of the matrix contiguous with the deuterides have a correspondingly enhanced aluminum and tantalum concentration.

Legzdina, D.↗

NASA NTRS1992

Deuterium in North Atlantic storm tops

During the ERICA project in 1989, ice crystals were collected from the tops of two winter storms and one broad cirrus cloud. Deuterium concentration in the storm ice samples, together with a model of isotope fractionation, are used to determine the temperature where the ice was formed. Knowledge of the ice formation temperature allows us to determine whether the ice has fallen or been lofted to the altitude of collection. In both storms, the estimated fall distance decreases upward. In the 21 January storm, the fall distance decreases to zero at the cloud top. In the 23 January storm, the fall distance decreases to zero at a point 2 km below the cloud top and appears to become negative above, indicating lofted ice. Cloud particle data from the cloud tops show an ice-to-vapor ratio greater than one and indicate the presence of particles with small terminal velocities; both observations support the idea of ice lofting. The satellite-derived cloud tops lie well below the actual cloud top (e.g., 2.5 km below on 23 January), indicating that the lofted ice in winter storms may not be detectable from space using IR radiance techniques. A comparison of deuterium in cloud-top ice and clear-air vapor suggests that even in winter, when vertical air motions are relatively weak, lofted ice crystals are the dominant source of water vapor in the upper troposphere.

Smith, Ronald B.↗

NASA NTRS1993

Fractionation of hydrogen and deuterium on Venus due to collisional ejection

The collisional ejection process for hydrogen on Venus is reanalyzed. Improved values for the efficiency of H and D escape as a function of the ionospheric temperature are reported. It is proposed that the reduction of the hydrogen flux for collisional ejection be reduced from 8 to 3.5 x 10 exp 6/sq cm/s, and a revised D/H fractional factor of 0.47 due to collisional ejection is suggested. The resulting deuterium flux is 3.1 x 10 exp 4/sq cm/s, roughly six times the flux due to charge exchange, making collisional ejection the dominant escape mechanism for deuterium on Venus.

Gurwell, Mark A.↗

NASA NTRS1994

The Strecker synthesis from interstellar precursors as a source of amino acids in carbonaceous chondrites: Deuterium retention during synthesis

Amino acids in the Murchison carbonaceous chondrite are anomalously enriched in deuterium. Synthesis in Strecker reactions from D-enriched interstellar precursors during low temperature aqueous alteration of the parent body has been proposed by Cronin et al. (1988) to account for the isotopic observations. To test this hypothesis, we have measured the retention of deuterium in the glycine, alanine, and alpha-amino isobutyric acid produced, respectively, by reactions of formaldehyde-D2, acetaldehyde-D4, and acetone-D6 with HCN and NH3 in water.

Lerner, N. R.↗