Ore deposits in volcanic rocks on earth with lunar extrapolation

Ore deposits in volcanic rocks on earth with lunar extrapolatio

High resolution solar X-ray studies

Two high resolution solar X-ray payloads and their launches on Aerobee rockets with pointing system are described. The payloads included 5 to 25A X-ray spectrometers, multiaperture X-ray cameras, and command box attitude control inflight by means of a television image radioed to ground. Spatial resolution ranged from five arc minutes to ten arc seconds and spectral resolution ranged from 500 to 3000. Several laboratory tasks were completed in order to achieve the desired resolution. These included (1) development of techniques to align grid collimators, (2) studies of the spectrometric properties of crystals, (3) measurements of the absorption coefficients of various materials used in X-ray spectrometers, (4) evaluation of the performance of multiaperture cameras, and (5) development of facilities

Constraints on the age and dilution of Pacific Exploratory Mission-Tropics biomass burning plumes from the natural radionuclide tracer 210Pb

During the NASA Global Troposphere Experiment Pacific Exploratory Mission-Tropics (PEM-Tropics) airborne sampling campaign we found unexpectedly high concentrations of aerosol-associated 210Pb throughout the free troposphere over the South Pacific. Because of the remoteness of the study region, we expected specific activities to be generally less than 35 μBq m−3 but found an average in the free troposphere of 107 μBq m−3. This average was elevated by a large number of very active (up to 405 μBq m−3) samples that were associated with biomass burning plumes encountered on nearly every PEM-Tropics flight in the southern hemisphere. We use a simple aging and dilution model, which assumes that 222Rn and primary combustion products are pumped into the free troposphere in wet convective systems over fire regions (most likely in Africa), to explain the elevated 210Pb activities. This model reproduces the observed 210Pb activities very well, and predicts the ratios of four hydrocarbon species (emitted by combustion) to CO to better than 20% in most cases. Plume ages calculated by the model depend strongly on the assumed 222Rn activities in the initial plume, but using values plausible for continental boundary layer air yields ages that are consistent with travel times from Africa to the South Pacific calculated with a back trajectory model. The model also shows that despite being easily recognized through the large enhancements of biomass burning tracers, these plumes must have entrained large fractions of the surrounding ambient air during transport

Rollup subsolar array Quarterly technical report, 5 Mar. - 30 May 1969

Thermal cycling and environmental tests for solar arra

Oxygen isotopic composition of carbon dioxide in the middle atmosphere

The isotopic composition of long-lived trace molecules provides a window into atmospheric transport and chemistry. Carbon dioxide is a particularly powerful tracer, because its abundance remains >100 parts per million by volume (ppmv) in the mesosphere. Here, we successfully reproduce the isotopic composition of CO2 in the middle atmosphere, which has not been previously reported. The mass-independent fractionation of oxygen in CO2 can be satisfactorily explained by the exchange reaction with O(1D). In the stratosphere, the major source of O(1D) is O3 photolysis. Higher in the mesosphere, we discover that the photolysis of 16O17O and 16O18O by solar Lyman-{alpha} radiation yields O(1D) 10–100 times more enriched in 17O and 18O than that from ozone photodissociation at lower altitudes. This latter source of heavy O(1D) has not been considered in atmospheric simulations, yet it may potentially affect the "anomalous" oxygen signature in tropospheric CO2 that should reflect the gross carbon fluxes between the atmosphere and terrestrial biosphere. Additional laboratory and atmospheric measurements are therefore proposed to test our model and validate the use of CO2 isotopic fractionation as a tracer of atmospheric chemical and dynamical processes

Laboratory measurement of the pure rotational spectrum of vibrationally excited HCO^+ (v_2 = 1) by far-infrared laser sideband spectroscopy

Laboratory observations of the pure rotational spectrum of HCO^+ in its lowest excited bending state (v_1, v^l_2 v_3)_= (0,1^1,0) are reported. Because of their severe excitation requirements, such vibrational satellites and the high-J ground-state lines also measured here sample only hot, dense regions of matter in active molecular cloud cores and circumstellar envelopes. As the HCO^+ abundance is tied directly to the gas fractional ionization, it is probable that the vibrationally excited formyl ion transitions will provide high-contrast observations of shocked molecular material, rather than the more quiescent, radiatively heated gas surrounding stellar sources detected with the few vibrationally excited neutral species observed to date

Mass inventory of the giant-planet formation zone in a solar nebula analog

The initial mass distribution in the solar nebula is a critical input to planet formation models that seek to reproduce today's Solar System. Traditionally, constraints on the gas mass distribution are derived from observations of the dust emission from disks, but this approach suffers from large uncertainties in grain growth and gas-to-dust ratio. On the other hand, previous observations of gas tracers only probe surface layers above the bulk mass reservoir. Here we present the first partially spatially resolved observations of the $^{13}$C$^{18}$O J=3-2 line emission in the closest protoplanetary disk, TW Hya, a gas tracer that probes the bulk mass distribution. Combining it with the C$^{18}$O J=3-2 emission and the previously detected HD J=1-0 flux, we directly constrain the mid-plane temperature and optical depths of gas and dust emission. We report a gas mass distribution of 13$^{+8}_{-5}\times$(R/20.5AU)$^{-0.9^{+0.4}_{-0.3}}$ g cm$^{-2}$ in the expected formation zone of gas and ice giants (5-21AU). We find the total gas/millimeter-sized dust mass ratio is 140 in this region, suggesting that at least 2.4M_earth of dust aggregates have grown to >centimeter sizes (and perhaps much larger). The radial distribution of gas mass is consistent with a self-similar viscous disk profile but much flatter than the posterior extrapolation of mass distribution in our own and extrasolar planetary systems.Comment: Definitive version of the manuscript is published in Nature Astronomy, 10.1038/s41550-017-0130. This is the authors' versio