Ionospheric research
Research projects in progress are reported. These include: planetary atmospheres, E- and F-region, and D-region.
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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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Small mass spectrometer with extended measurement capabilities at high pressures
For the in situ investigation of planetary atmospheres a small Mattauch-Herzog mass spectrometer has been developed. Its high-pressure performance has been improved by incorporating differential pumping between the ion source and the analyzing fields, shortening the path-length as well as increasing the extraction field in the ion source. In addition doubly ionized and dissociated ions are used for mass analysis. These measures make possible operation up to 0.01 millibars. Results of laboratory tests related to linearity, dynamic range, and mass resolution are presented, in particular for CO2.
Von Zahn, U.↗
Turbulence in planetary occultations. IV - Power spectra of phase and intensity fluctuations
Power spectra of phase and intensity scintillations during occultation by turbulent planetary atmospheres are significantly affected by the inhomogeneous background upon which the turbulence is superimposed. Such coupling is particularly pronounced in the intensity, where there is also a marked difference in spectral shape between a central and grazing occultation. While the former has its structural features smoothed by coupling to the inhomogeneous background, such features are enhanced in the latter. Indeed, the latter power spectrum peaks around the characteristic frequency that is determined by the size of the free-space Fresnel zone and the ray velocity in the atmosphere; at higher frequencies strong fringes develop in the power spectrum. A confrontation between the theoretical scintillation spectra computed here and those calculated from the Mariner 5 Venus mission by Woo et al. (1974) is inconclusive, mainly because of insufficient statistical resolution. Phase and/or intensity power spectra computed from occultation data may be used to deduce characteristics of the turbulence and to distinguish turbulence from other perturbations in the refractive index. Such determinations are facilitated if observations are made at two or more frequencies (radio occultation) or in two or more colors (stellar occultation).
Haugstad, B. S.↗
Hydrogen atom initiated chemistry
H Atoms have been created by the photolysis of H2S. These then initiated reactions in mixtures involving acetylene-ammonia-water and ethylene-ammonia-water. In the case of the acetylene system, the products consisted of two amino acids, ethylene and a group of primarily cyclic thio-compounds, but no free sulfur. In the case of the ethylene systems, seven amino acids, including an aromatic one, ethane, free sulfur, and a group of solely linear thio-compounds were produced. Total quantum yields for the production of amino acids were about 3 x 10 to the -5th and about 2 x 10 to the -4th with ethylene and acetylene respectively as carbon substrates. Consideration is given of the mechanism for the formation of some of the products and implications regarding planetary atmosphere chemistry, particularly that of Jupiter, are explored.
Hong, J. H.↗
Three-dimensional optimum maneuvers of a hypervelocity vehicle
In this paper the optimum three-dimensional maneuver in lift and bank control of a reentry vehicle is investigated. The use of the modified Chapman's variables and a normalized lift coefficient allows a general discussion of the optimum control of an arbitrary vehicle reentering any planetary atmosphere. Several planar problems are solved. Using the condition of equilibrium glide, the maximum cross range and the footprint of a reentry vehicle from circular speed are computed in terms of the maximum lift-to-drag ratio.
Vinh, N. X.↗
Trajectories optimization in hypersonic flight
Equations of motion were derived for the three dimensional flight of a lifting vehicles, taking into consideration all the main effects of different forces acting on a vehicle at orbital speeds. A set of equations was formulated which are valid for both the flight with lift modulation inside a planetary atmosphere and the Keplerian motion in the vacuum. The equations are independent of the physical characteristics of the vehicle. The only parameters involved are the maximum lift to drag ratio of the vehicle and a constant characterizing the atmosphere. The results obtained can be applied without modifications to any future reentry vehicle, regardless of its size, shape, and mass.
Vinh, N. X.↗
Infrared heterodyne spectroscopy in astronomy
A heterodyne spectrometer was constructed and applied to problems in infrared astronomical spectroscopy. The instrument offers distinct observational advantages for the detection and analysis of individual spectral lines at Doppler-limited resolution. Observations of carbon dioxide in planetary atmospheres and ammonia in circumstellar environments demonstrate the substantial role that infrared heterodyne techniques will play in the astronomical spectroscopy of the future.
Betz, A.↗
Pressure dependence of the absolute rate constant for the reaction OH + C2H2 from 228 to 413K
The pressure dependence of absolute rate constants for the reaction of OH + C2H2 yields products has been examined at five temperatures ranging from 228 to 413 K. The experimental techniques which was used is flash photolysis-resonance fluoresence. OH was produced by water photolysis and hydroxyl resonance fluorescent photons were measured by multiscaling techniques. The results indicate that the low pressure bimolecular rate constant is 4 x 10 the the minus 13th power cu cm molecule (-1) s(-1) over the temperature range studied. A substantial increase in the bimolecular rate constant with an increase in pressure was observed at all temperatures except 228 K. This indicates the importance of initial adduct formation and subsequent stablization. The high pressure results are well represented by the Arrhenius expression (k sub bi) sub infinity = (6.83 + or - 1.19) x 10 to the minus 12th power exp(-646 + or - 47/T)cu cm molecule (-1) s(-1). The results are compared to previous investigated and are theoretically discussed. The implications of these results on modeling of terrestrial and planetary atmospheres and also in combustion chemistry are discussed.
Michael, J. V.↗
On the formation of nonlinear internal waves from the gravitational collapse of mixed regions in two and three dimensions
The paper shows how trains of nonlinear, dispersive waves can be produced by allowing a region of mixed fluid, with a potential energy greater than its surroundings, to collapse towards its equilibrium state. The number of waves and their amplitude depend on the properties of the mixed region and of the ambient stratification. Three different geometrical configurations have been chosen and while each gives qualitatively the same results the form taken by the generated waves and the final equilibrium shape of the mixed region depend critically on these geometrical factors. The internal waves produced by this mechanism are related to waves produced in natural systems and it is shown that the observations support at least one possible explanation for those found in the oceans and planetary atmospheres.
Maxworthy, T.↗
Anomalous /C-13/H4:/C-12/H4 line strengths in 2 nu 3
Anomalous intensity ratios between 2 nu 3 singlet lines of C-13 methane and C-12 methane are reported. Absolute strengths of the Q1, R0 and R1 singlets were measured for essentially pure samples of (C-13)H4 and (C-12)H4 at a resolution of 0.035 kaysers at pressures of 10 and 20 Torr, using a computer controlled grating spectrometer. Line strength ratios between the isotopic species are presented which demonstrate a dramatic effect of isotopic substitution on line strengths. If this effect can be observed in the 3 nu 3 vibration-rotation band of methane, which is widely used in planetary atmosphere studies, revision of the (C-12)H4/(C-13)H4 abundance ratios of the outer planets will be necessary.
Fox, K.↗
New theoretical and experimental methods for pressure broadened linewidths and their interpretation
A review of recent progress in the theory of collisional line broadening, particularly the impact of recent advances in collision dynamics calculations is presented. Some new approaches to the interpretation of experimentally measured linewidths and their impact on planetary atmosphere research are discussed. Experimental techniques which may have some advantage in providing pressure broadening data at very low temperatures are also mentioned.
Gelfand, J. J.↗
Microwave rotational spectroscopy
The region of planetary atmospheres upward of 1 millimeter is considered. The applications of this region, how microwave, millimeter, and submillimeter spectra (the so called rotational spectra) can fruitfully interact with infrared spectral measurements are described. Both the rotational bands and vibrational bands of molecules are considered. A typical rotational absorption coefficient for a linear molecule in a low J state with a dipole moment of about one Debye is plotted and evaluated. A vibrational case was chosen similarly: the transition dipole moment used for the vibrational case is typical of CO at the peak of its rotational distribution. Information on high altitude parameters that often cannot be obtained from higher frequency spectra, which can be provided by rotational spectra is discussed.
Pickett, H.↗
The JPL millimeter, submillimeter and microwave line catalog
The catalog includes molecules of interest in the interstellar medium, in planetary atmospheres and in the Earth's atmosphere. Different units than those on the AFGL tape are used. For citing line frequencies in the microwave region. Either the experimental errors or the propagation of errors from the fit are included on the tape. This gives an estimate of how accurate the frequencies are. The intensity units are defined as follows: the logarithm of the intensity unit is the cross section times the frequency in MHz. This is essentially the same unit as on the AFGL tape, but contains fewer factors of the speed of light. The catalog is available to the scientific community either as a tape or on microfiche (filmed in frequency sorted and molecule sorted format).
Pickett, H.↗
Infrared absorption of sulfur bearing compounds
The sulfur bearing molecules of most interest in studies of planetary atmospheres are the simple, stable hydrides and oxides, H2S, H2SO4, SO2, and SO3, and the carbon containing species OCS and CO2. For interpreting spectroscopic observations, the properties that must be known are: transition frequencies, transition intensities, transition assignments in terms of quantum number assignments and lower state energy levels, and pressure broadening constants (including their temperature dependence).
Maki, A.↗
Current studies of PH3
Recent quantitative spectroscopic studies of the PH3 fundamentals in the 10 and 4.5 micrometer regions resulted in line parameters applicable to spectral radiative models of planetary atmospheres. These include theoretical line parameters for the (nu sub 2 (A sub 1), nu sub 4 (E)) and (nu sub 1 (A sub 1), nu sub 3 (E)) regions, and empirical line parameters for the 2 nu sub 2, 2 nu sub 4 and nu sub 2 + nu sub 4 bands overlapping the (nu sub 1, nu sub 3) region. The theoretical line parameters were normalized to previously published values derived from low resolution spectra and are presented.
Goldman, A.↗
Space environment and lunar surface processes, 2
The top few millimeters of a surface exposed to space represents a physically and chemically active zone with properties different from those of a surface in the environment of a planetary atmosphere. To meet the need or a quantitative synthesis of the various processes contributing to the evolution of surfaces of the Moon, Mercury, the asteroids, and similar bodies, (exposure to solar wind, solar flare particles, galactic cosmic rays, heating from solar radiation, and meteoroid bombardment), the MESS 2 computer program was developed. This program differs from earlier work in that the surface processes are broken down as a function of size scale and treated in three dimensions with good resolution on each scale. The results obtained apply to the development of soil near the surface and is based on lunar conditions. Parameters can be adjusted to describe asteroid regoliths and other space-related bodies.
Comstock, G. M.↗
IUE observations of solar system objects and processes
International Ultraviolet Explorer (IUE) observations of the planets and their satellites, comets, and asteroids are discussed. The use of IUE to identify previously undetected absorption features in planetary atmospheres and magnetospheres, and identify and map the distribution of constituents on the surfaces of solid bodies are covered. The advantages of the IUE over fly-by missions are outlined.
Nelson, R. M.↗
Activities in planetary geology for the physical and earth sciences
A users guide for teaching activities in planetary geology, and for physical and earth sciences is presented. The following topics are discussed: cratering; aeolian processes; planetary atmospheres, in particular the Coriolis Effect and storm systems; photogeologic mapping of other planets, Moon provinces and stratigraphy, planets in stereo, land form mapping of Moon, Mercury and Mars, and geologic features of Mars.
Dalli, R.↗