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Martin, W.

Publications and source records attributed to Martin, W..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Space-Based Remote Sensing of Atmospheric Aerosols: The Multi-Angle Spectro-Polarimetric Frontier

The review of optical instrumentation, forward modeling, and inverse problem solution for the polarimetric aerosol remote sensing from space is presented. The special emphasis is given to the description of current airborne and satellite imaging polarimeters and also to modern satellite aerosol retrieval algorithms based on the measurements of the Stokes vector of reflected solar light as detected on a satellite. Various underlying surface reflectance models are discussed and evaluated.

polarimetry↗
NASA NTRS2003

Self-Reacting Friction Stir Welding for Aluminum Complex Curvature Applications

This viewgraph representation provides an overview of sucessful research conducted by Lockheed Martin and NASA to develop an advanced self-reacting friction stir technology for complex curvature aluminum alloys. The research included weld process development for 0.320 inch Al 2219, sucessful transfer from the 'lab' scale to the production scale tool and weld quality exceeding strenght goals. This process will enable development and implementation of large scale complex geometry hardware fabrication. Topics covered include: weld process development, weld process transfer, and intermediate hardware fabrication.

Brown, Randy J.↗
NASA NTRS2000

FQPSK Developments Recommended for CCSDS Standardization by NASA/JPL

In 1992, international space agencies became concerned that increasing frequency band congestion, together with attempts by the mobile telephone industry to obtain additional bandwidth, would result in substantially more interference incidents.

modulation Feher's quadrature phase shift keying b↗
NASA NTRS1999

Regiochemical control of monolignol radical coupling: a new paradigm for lignin and lignan biosynthesis

BACKGROUND: Although the lignins and lignans, both monolignol-derived coupling products, account for nearly 30% of the organic carbon circulating in the biosphere, the biosynthetic mechanism of their formation has been poorly understood. The prevailing view has been that lignins and lignans are produced by random free-radical polymerization and coupling, respectively. This view is challenged, mechanistically, by the recent discovery of dirigent proteins that precisely determine both the regiochemical and stereoselective outcome of monolignol radical coupling. RESULTS: To understand further the regulation and control of monolignol coupling, leading to both lignan and lignin formation, we sought to clone the first genes encoding dirigent proteins from several species. The encoding genes, described here, have no sequence homology with any other protein of known function. When expressed in a heterologous system, the recombinant protein was able to confer strict regiochemical and stereochemical control on monolignol free-radical coupling. The expression in plants of dirigent proteins and proposed dirigent protein arrays in developing xylem and in other lignified tissues indicates roles for these proteins in both lignan formation and lignification. CONCLUSIONS: The first understanding of regiochemical and stereochemical control of monolignol coupling in lignan biosynthesis has been established via the participation of a new class of dirigent proteins. Immunological studies have also implicated the involvement of potential corresponding arrays of dirigent protein sites in controlling lignin biopolymer assembly.

NASA Discipline Plant Biology↗
NASA NTRS1995

Communication System Architectures for Missions to Mars - A Preliminary Investigation

This paper presents various communication system architectures for Multiple-Link communications with Single Aperture (MULSA) ground station. The proposed architectures are capable of supporting a multiplicity of spacecraft that are within the beamwidth of a single ground station antenna simultaneously. Both short and long term proposals to address this scenario will be discussed. In addition, the paper also discusses the top-level system designs of the proposed architectures and attempts to identify the associated advantages and disadvantages for each system.

antenna↗
NASA NTRS1993

(abstract) Hermes Global Orbiter: Mission to Mercury

The Hermes Global Orbiter is a proposed Discovery-class mission. Hermes will be launched aboard a Delta II rocket in 1999 and will be placed in an elliptical polar orbit about Mercury. Remote sensing measurements of the planet's surface, atmosphere, and magnetosphere will be performed. Key mission goals include mapping the entire surface at 1 km resolution, characterizing the surface composition, texture and topography, searching for water ice at the poles, characterizing the atmosphere, and constraining the interior structure.

Mercury Hermes orbiter remote sensing surface atmo↗
NASA NTRS1975

Experimental test of general relativity using time-delay data from Mariner 6 and Mariner 7

Range and Doppler data from Mariner 6 and Mariner 7 have been analyzed for purposes of measuring the effect of the sun's gravity field on S-band radio transmissions to the spacecraft. The prediction of general relativity, that the round-trip time delays between the station and the spacecraft will be increased by about 200 microsec near superior conjunction, has been verified with an uncertainty of 3 per cent or less. The dominant error source on the experiment is the stochastic nongravitational forces which act on the spacecraft and which limit the accuracy of the determination of the Mariner orbits. Effects of free coronal electrons on the round-trip propagation also make the measurement difficult, but the coronal contribution to the error is only about 1 per cent. Separate analyses of data from Mariner 6 and Mariner 7 yield two values near unity for the parameter gamma* which differ by about 0.3 per cent from each other. This and other considerations suggest that the error in the experiment is perhaps less than 3 per cent.

Anderson, J. D.↗
NASA NTRS1972

Graphite epoxy reflector support truss for applications technology satellite /ATS/.

The design, development, fabrication, and qualification load testing of the reflector support truss for Applications Technology Satellites F and G are described. Because the truss is stability-critical, high modulus graphite epoxy composite was used to provide a minimum weight structure. The work was performed under the sponsorship of the NASA Goddard Space Flight Center with Fairchild Industries as the prime contractor.

Randolph, R. E.↗
NASA NTRS1971

Geochemical aspects of some Japanese lavas.

K, Rb, Sr, Ba and rare-earth concentrations in some Japanese lavas have been determined by mass-spectrometric stable-isotope dilution. The samples fall into three rare-earth groups corresponding to tholeiitic, high alumina and alkali basalts. Japanese tholeiites have trace element characteristics similar to those of oceanic ridge tholeiites except for distinctly higher relative concentrations of Ba. Japanese lavas may result from various degrees of partial fusion of amphibole eclogite.

Philpotts, J. A.↗