Engineering Papers⌕ Search

Engineering topics

Baker, M. B.

Publications and source records attributed to Baker, M. B..

12 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Mineralogy and Genesis of the Windjana Sandstone, Kimberley Area, Gale Crater, Mars

MSL Curiosity investigated the Windjana sandstone outcrop, in the Kimberley area of Gale Crater, and obtained mineralogical analyses with the CheMin XRD instrument. Windjana is remarkable in containing an abundance of potassium feldspar (and thus K in its bulk chemistry) combined with a low abundance of plagioclase (and low Na/K in its chemistry). The source of this enrichment in K is not clear, but has significant implications for the geology of Gale Crater and of Mars. The high K could be intrinsic to the sediment and imply that the sediment source area (Gale Crater rim) includes K-rich basalts and possibly more evolved rocks derived from alkaline magmas. Alternatively, the high K could be diagenetic and imply that the Gale Crater sediments were altered by K-rich aqueous fluids after deposition.

Treiman, A. H.↗
NASA NTRS1999

Inferring Selected Cloud Properties from Satellite Lightning Data

The recent advent of satellite lightning detection programs has introduced a new potential for obtaining global information about other (hard to measure) cloud properties. We have made use of observations together with numerical model studies to show that positive correlations exist between: (1) lightning flashrate (F) and vertical velocity (w); and (2) flashrate (F) and the amount of condensate (water and ice) lofted through the -10 C isotherm (C(sub u)). The lightning flashrate appears to be very sensitive to the magnitude of the updraft velocity, with F increasing rapidly with w above a threshold of w approx. = 5-10 m/s. By contrast, we have found that the flashrate/condensate relationship appears to be approximately linear. We are currently refining the F-updraft and F-condensate relationships with further model studies before applying them to lightning data from the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS). We hope, with this method, to provide estimates of the large scale vertical water transport by continental convective systems over seasonal timescales.

Schroeder, Vicki↗
NASA NTRS1990

Structural analysis of stratocumulus convection

The 1 and 20 Hz data are examined from the Electra flights made on July 5, 1987. The flight legs consisted of seven horizontal turbulent legs at the inversion, midcloud, and below clouds, plus 4 soundings made within the same period. The Rosemont temperature sensor and the top and bottom dewpoint sensors were used to measure temperature and humidity at 1 Hz. Inversion structure and entrainment; local dynamics and large scale forcing; convective elements; and decoupling of cloud and subcloud are discussed in relationship to the results of the Electra flight.

Siems, S. T.↗
NASA NTRS1990

Simulations and observations of cloudtop processes

Turbulent entrainment at zero mean shear stratified interfaces has been studied extensively in the laboratory and theoretically for the classical situation in which density is a passive tracer of the mixing and the turbulent motions producing the entrainment are directed toward the interface. It is the purpose of the numerical simulations and data analysis to investigate these processes and, specifically, to focus on the following questions: (1) Can local cooling below cloudtop play an important role in setting up convective circulations within the cloud, and bringing about entrainment; (2) Can Cloudtop Entrainment Instability (CEI) alone lead to runaway entrainment under geophysically realistic conditions; and (3) What are the important mechanisms of entrainment at cloudtop under zero or low mean shear conditions.

Siems, S. T.↗
NASA NTRS1982

Olivine flotation and settling experiments on the join Mg2SiO4-Fe2SiO4

Results are presented of a study of some unusual density relations between olivine and coexisting liquid in the system fosterite-fayalite. At 1 atmosphere pressure it is found that olivine floats on its coexisting liquid for intermediate compositions on this binary because of extreme partitioning of Fe into the melt phase. At 20 kilobars, the usual behavior of olivine settling is found to occur because the partitioning of Fe in the melt is reduced, aided possibly by the dissolution of CO2 in the melt from the use of a graphite container. It is determined that olivine flotation and settling are rapid in a time period of only a few hours because viscosities are slightly greater than that of paraffin oil at room temperature. Some adcumulate textures with good triple junction grain boundaries are found to be developed. Observations of differentiated magmatic systems suggest that the mechanisms by which magmas can differentiate vary considerably in the ultramafic to tholeiitic compositional range.

Herzberg, C. T.↗
NASA NTRS1980

The cordierite- to spinel-cataclasite transition - Structure of the lunar crust

A two-layer lunar crust model is proposed in light of geochemical relationships between spinel cataclasites and anorthosites, discussing the relative abundances of these rocks. The uppermost stratigraphic unit of this model consists of members of the anorthositic series, and is estimated to be 12-20 km thick. The lower, Mg-rich unit consists of rocks with cotectic mineralogical proportions, and may constitute the greatest volume of the crust.

Herzberg, C. T.↗
NASA NTRS1980

Spinel cataclasites in 15445 and 72435 - Petrology and criteria for equilibrium

The problem of establishing the existence of equilibrium among the coexisting phases in the rock is addressed by presenting petrographic and mineral chemistry data on a new spinel cataclasite from 15445 (clast H) and data more extensive than those previously available on two clasts in 72435. Criteria useful in reconstructing the original petrology of these and other spinel cataclasites are analyzed by considering equilibrium among the different phases, that is, the mono- or polymict nature of these cataclasized samples. Finally, the role of impact processes in disturbing the equilibria is discussed.

Baker, M. B.↗
NASA NTRS1975

The McDonnell Douglas geophysical observatory program progress report 13 Conjugate point riometer program

This report, the thirteenth and final progress report on the McDonnell Douglas Geophysical Observatory Program, discusses history of the program from 1962 through 1973, and results of the research carried out in 1974. Topic areas covered include: Station operation; Ionospheric work; Solar studies, Magnetospheric studies; Satellite measurements; International participation; and, 1974 research on solar activity, ATS-6 studies, magnetospheric physics, and station operation.

Baker, M. B.↗
NASA NTRS1974

Simultaneous satellite and riometer studies

The expected 30 and 50 MHz riometer absorption was calculated for the 7 June, 25 September and 2 November 1969 solar events using data from the McDonnell Douglas charged particle experiment on the polar orbiting OGO-6 Satellite. Excellent agreement was found between measured polar cap riometer absorption during the events and absorption calculated from detailed particle data obtained on the satellite passing over the riometer. Electrons are found to contribute the greater part of the 30 MHz absorption before the peak of the 2 November 1969 event; at all other times protons produce most of the absorption. The alpha-particle contribution is negligible in all cases.

Baker, M. B.↗
NASA NTRS1972

Simultaneous satellite and riometer measurements of particles during solar cosmic ray events.

The expected 30 and 50 MHz riometer absorptions have been calculated for three events in 1969 using data from the MDAC-W charged particle experiment on OGO 6. Several times during each event, the satellite passed over the MDAC-W Arctic and Antarctic Geophysical Observatories. The calculated total absorption (using 2 minute averages of the data) agrees well with the measured absorption for the overpasses. The alpha particle and electron contributions usually amount to less than a few percent of the proton absorption. During the large November 2, 1969 event, however, the electrons produced the major part of the absorption up to the peak and a significant contribution during virtually its entire duration. With the two frequencies for which simultaneous riometer data were taken, it is possible to detect the softening of the particle spectra during the events, and the relative hardness differences between events.

Baker, M. B.↗