Search for Life

NASA\u27s Astrobiology program seeks to determine the origin and distribution of life in the Milky Way galaxy using scientific expertise from many disciplines (e.g., astronomy, biochemistry, geochemistry). This presentation, which provides an overview of the progress that has been made in this effort, was delivered on 23 June 2015 at the Green Mountain Academy for Lifelong Learning in Manchester, VT. With NASA\u27s development of the Space Launch System (SLS), vigorous multi-disciplinary scientific research, and additional spacecraft (e.g., TESS) for finding and analyzing planets orbiting other stars, exciting discoveries will continue

Measurements of geomagnetic declination (1685-1910) using land surveys, LiDAR, and stone walls

Nearly 1200 kilometers of boundaries surveyed in 1685-1910, upon which stone walls were subsequently built, were measured using high-resolution LiDAR (Light Detection and Ranging) in the northeastern United States (New Hampshire and New York). The geomagnetic declinations at the time of the original land surveys of those stone wall-defined boundaries have been determined and compared with (i) current geophysical models (i.e., gufm1, IGRF12; United States Historical Declinations-USHD), and (ii) measured declinations (Bauer, 1902). With the exception of lower declinations (i.e., 1.5° eastward) in 1775-1810, the results of this study are in good agreement with gufm1 and IGRF12 geomagnetic declinations. This study yielded systematically higher declinations (i.e., up to 2.0° westerly) than the USHD values during 1750-1780. These results demonstrate that geomagnetic declination can be determined when durable, human-engineered structures on land (e.g., stone walls; roads) are accompanied by detailed historical documentation and accurate land surveys. An example of using old streets (1699) in Colonial Williamsburg, VA is also discussed. Precisions of the bearings along boundaries in the 17th-19th century land surveys used this study were typically better than ±0.30°

Stone Walls of New York and New England

Stone walls are an enduring testimony of the hard labors and work ethic of subsistence family farms on ~100-acre lots. Those lots had been defined by hardy teams of surveyors who used compasses and chains to define the magnetic directions and lengths of boundaries. Farmers cleared (‘improved’) large sections of their land of trees for the purpose of grazing animals and growing crops. As we venture into the deep woods today, we often encounter these forgotten stonewalls that reveal that others long ago were there. Modern airborne surveys using ‘Light Detection And Ranging’ (LiDAR) not only reveal the vast extent of these stone monuments in New York and New England (total estimated length ~200,000 miles), but also information about the slow drift of the Earth’s magnetic field

40Ar/39Ar ages of lunar impact glasses: Relationships among Ar diffusivity, chemical composition, shape, and size

Lunar impact glasses, which are quenched melts produced during cratering events on the Moon, have the potential to providenot only compositional information about both the local and regional geology of the Moon but also information about the impact flux over time. We present in this paper the results of 73 new 40Ar/39Ar analyses of well-characterized, inclusion-free lunar impact glasses and demonstrate that size, shape, chemical composition, fraction of radiogenic 40Ar retained, and cosmic ray exposure (CRE) ages are important for 40Ar/39Ar investigations of these samples. Specifically, analyses of lunar impact glasses from the Apollo 14, 16, and 17 landing sites indicate that retention of radiogenic 40Ar is a strong function of post-formation thermal history in the lunar regolith, size, and chemical composition. This is because the Ar diffusion coefficient (at a constant temperature) is estimated to decrease by 3–4 orders of magnitude with an increasing fraction of non-bridging oxygens, X(NBO), over the compositional range of most lunar impact glasses with compositions from feldspathic to basaltic. Based on these relationships, lunar impact glasses with compositions and sizes sufficient to have retained 90% of their radiogenic Ar during 750 Ma of cosmic ray exposure at time-integrated temperatures of up to 290 K have been identified and are likely to have yielded reliable 40Ar/39Ar ages of formation. Additionally, 50% of the identified impact glass spheres have formation ages of 6500 Ma, while 75% of the identified lunar impact glass shards and spheres have ages of formation 62000 Ma. Higher thermal stresses in lunar impact glasses quenched from hyperliquidus temperatures are considered the likely cause of poor survival of impact glass spheres, as well as the decreasing frequency of lunar impact glasses in general with increasing age. The observed age-frequency distribution of lunar impact glasses may reflect two processes: (i) diminished preservation due to spontaneous shattering with age; and (ii) preservation of a remnant population of impact glasses from the tail end of the terminal lunar bombardment having 40Ar/39Ar ages up to 3800 Ma. A protocol is described for selecting and analyzing lunar impact glasses

Transfer student analysis and retention: a collaborative endeavor

This paper aims to describe a multifaceted campus-wide initiative to retain transfer students that was undertaken when it was recognized that their retention rates were lower than those of first-time, full-time students. The “all-hands-on-deck” approach described in this paper demonstrates how strategic collaborations among the many institutional stakeholders at a public research university were marshalled to have a significant and positive impact on student retention