A Gemini mosaic along the thirty second degree of latitude from Baja California to Central Texas

Mosaic of western united states constructed from spaceborne photographs taken on Gemini flight

A photo-mosaic of western Peru from Gemini photography

Photo-mosaic of western Peru composed of photographs taken from Gemini

Classification of supersymmetric spacetimes in eleven dimensions

We derive, for spacetimes admitting a Spin(7) structure, the general local bosonic solution of the Killing spinor equation of eleven dimensional supergravity. The metric, four form and Killing spinors are determined explicitly, up to an arbitrary eight-manifold of Spin(7) holonomy. It is sufficient to impose the Bianchi identity and one particular component of the four form field equation to ensure that the solution of the Killing spinor equation also satisfies all the field equations, and we give these conditions explicitly.Comment: 9 pages, latex. v2: change of title (formerly known as "Spin(7) structures in eleven dimensions"); short section on integrability conditions added, various minor changes. To appear in Phys.Rev.Let

A Survey and Evaluation of High Energy Liquid Chemical Propulsion Systems

This report presents the results of a study to develop a procedure for evaluating liquid propellants in order (a) to select the most appropriate propellant (from among those under development) for each of several applications on each of the various missions in the NASA program, or (b) to select new propellants (from among those being proposed) for initiation or continuation of research and development. The analysis begins with a consideration of requirements--either for the specific application or for the various classes of applications. The known characteristics of the propellant or propellants to be evaluated are then put into a convenient form for evaluation. The next step is to determine whether or not there are requirements that simply cannot be met by the propellant. If the propellant passes this test, an optimum vehicle configuration using the propellant (and meeting all requirements) is estimated. (The configuration should be optimized with respect to the total resource consumption for all aspects of the mission, including R&D, production, logistics, and operation.) The total resource consumption for this configuration is then compared with that for similar configurations using other propellants (and meeting all requirements equally well). If all factors have been properly taken into account, this comparison of resource consumption will complete the evaluation. Such an evaluation may be performed several times, in increasing detail and with correspondingly increasing accuracy, as an R&D program proceeds, and the accuracy of the data as well as the cost of the next step in the program increase. The procedure is superior to those in common use in that it minimizes both the amount of analytical work and the number of points at which subjective value judgments are made

An all monolithic MOS A/D converter - Low power clocks, multiplexers, registers, and A/D converter Final report

Research and developments of monolithic, MOS, ten bit, analog to digital converte

Geological utilization of Gemini color photograph of Duba area, Saudi Arabia

Geological fault in Duba area, Saudi Arabia, observed on Gemini 5 color photograp

GAIA: AGB stars as tracers of star formation histories in the Galaxy and beyond

We discuss the tracing of star formation histories with ESA's space astrometry mission GAIA, emphasizing the advantages of AGB stars for this purpose. GAIA's microarcsecond-level astrometry, multi-band photometry and spectroscopy will provide individual distances, motions, effective temperatures, gravities and metallicities for vast numbers of AGB stars in the Galaxy and beyond. Reliable ages of AGB stars can be determined to distances of \~200 kpc in a wide range of ages and metallicities, allowing star formation histories to be studied in a diversity of astrophysical environments.Comment: 4 pages, 1 figure, to be appear in 'Mass-Losing Pulsating Stars and their Circumstellar Matter', eds. Y. Nakada, M. Honma & M. Seki, Kluwer ASSL series, vol. 28

The geometry of extended null supersymmetry in M-theory

For supersymmetric spacetimes in eleven dimensions admitting a null Killing spinor, a set of explicit necessary and sufficient conditions for the existence of any number of arbitrary additional Killing spinors is derived. The necessary and sufficient conditions are comprised of algebraic relationships, linear in the spinorial components, between the spinorial components and their first derivatives, and the components of the spin connection and four-form. The integrability conditions for the Killing spinor equation are also analysed in detail, to determine which components of the field equations are implied by arbitrary additional supersymmetries and the four-form Bianchi identity. This provides a complete formalism for the systematic and exhaustive investigation of all spacetimes with extended null supersymmetry in eleven dimensions. The formalism is employed to show that the general bosonic solution of eleven dimensional supergravity admitting a $G_2$ structure defined by four Killing spinors is either locally the direct product of $\mathbb{R}^{1,3}$ with a seven-manifold of $G_2$ holonomy, or locally the Freund-Rubin direct product of $AdS_4$ with a seven-manifold of weak $G_2$ holonomy. In addition, all supersymmetric spacetimes admitting a $(G_2\ltimes\mathbb{R}^7)\times\mathbb{R}^2$ structure are classified.Comment: 36 pages, latex; v2, section classifying all spacetimes admitting a $(G_2\ltimes\mathbb{R}^7)\times\mathbb{R}^2$ structure included; v3, typos corrected. Final version to appear in Phys.Rev.

Solar-radiation-induced damage to optical properties of ZnO-type pigments Technical summary report, Jul. 1966 - Feb. 1968

Mechanisms of solar radiation damage to optical properties in zinc oxide pigments in visible and infrared region