Warren C. Kelliher

Inorganic analyses of Martian surface samples at the Viking landing sites

Elemental analyses of fines in the Martian regolith at two widely separated landing sites, Chryse Planitia and Utopia Planitia, produced remarkably similar results. At both sites, the uppermost regolith contains abundant Si and Fe, with significant concentrations of Mg, Al, S, Ca, and Ti. The S concentration is one to two orders of magnitude higher, and K(<0.25 percent by weight) is at least 5 times lower than the average for the earths crust. The trace elements Sr, Y, and possibly Zr, have been detected at concentrations near or below 100 parts per million. Pebblesized fragments sampled at Chryse contain more S than the bulk fines, and are thought to be pieces of a sulfate-cemented duricrust.

Performance of a Borehole X-Ray Fluorescence Spectrometer for Planetary Exploration

We have designed and constructed a borehole X-ray fluorescence spectrometer (XRFS) as part of the Mars Subsurface Access program (http://marstech.jpl.nasa.gov/content/detail.cfm?Sect=MTP&Cat=base&subCat=SSA&subSubCat=&TaskID=2256). It can be used to determine the composition of the Mars regolith at various depths by insertion into a pre-drilled borehole. The primary requirements and performance metrics for the instrument are to obtain parts-per-million (ppm) lower limits of detection over a wide range of elements in the periodic table (magnesium to lead). Power consumption during data collection was also measured. The prototype instrument is complete and preliminary testing has been performed. terrestrial soil standard reference materials were used as the test samples. Detection limits were about 10 weight ppm for most elements, with light elements being higher, up to 1.4 weight percent for magnesium. Power consumption (excluding ground support components) was 12 watts.

Tumbleweed: A New Paradigm for Surveying the Surface of Mars for In-Situ Resources

Mars missions to date have interrogated the planet at very large scales using orbital platforms or at very small scales intensively studying relatively small patches of terrain. In order to facilitate discovery and eventual utilization of Martian resources for future missions, a strategy that will bridge these scales and allow assessment of large areas of Mars in pursuit of a resource base will be essential. Long-range surveys of in-situ resources on the surface of Mars could be readily accomplished with a fleet of Tumbleweeds - vehicles capable of using the readily available Martian wind to traverse the surface of Mars with minimal power, while optimizing their capabilities to perform a variety of measurements over relatively large swaths of terrain. These low-cost vehicles fill the niche between orbital reconnaissance and landed rovers, which are capable of much more localized study. Fleets of Tumbleweed vehicles could be used to conduct long-range, randomized surveys with simple, low-cost instrumentation functionally equivalent to conventional coordinate grid sampling. Gradients of many potential volatile resources (e.g. H2O, CH4, etc.) will also tend to follow wind-borne trajectories thus making the mobility mode of the vehicles well matched to the possible target resources. These vehicles can be suitably instrumented for surface and near-surface interrogation and released to roam for the duration of a season or longer, possibly on the residual ice cap or anywhere orbital surveillance indicates that usable resources may exist. Specific instrument selections can service the exact exploration goals of particular survey missions. Many of the desired instruments for resource discovery are currently under development for in-situ applications, but have not yet been miniaturized to the point where they can be integrated into Tumbleweeds. It is anticipated that within a few years, instruments such as gas chromatograph mass spectrometers (GC-MS) and ground-penetrating radar (GPR) will be deployable on Tumbleweed vehicles. The wind-driven strategy conforms to potential natural gradients of moisture and potentially relevant resource gases that also respond to wind vectors. This approach is also useful for characterizing other resources and performing a variety of basic science missions. Inflatable and deployable structure Tumbleweeds are wind-propelled long-range vehicles based on well-developed and field tested technology (Antol et al., 2005; Behar et al., 2004; Carsey et al., 2004; Jones and Yavrouian, 1997; Wilson et al., 2008). Different Tumbleweed configurations can provide the capability to operate in varying terrains and accommodate a wide range of instrument packages making them suitable for autonomous surveys for in-situ natural resources. Tumbleweeds are lightweight and relatively inexpensive, making them very attractive for multiple deployments or piggybacking on larger missions.

Fabricating multifilamentary high-Tc superconducting bismuth cuprate tapes by metalorganic chemical spray pyrolysis

Abstract This paper reports preliminary findings on research to develop chemical spray pyrolysis as a method for synthesizing multifilamentary bismuth cuprate (BSCCO) tape and wire components. Chemical spray pyrolysis is a solution process that allows oxide precursor material to be rapidly deposited on a variety of substrate materials. It is an inherently low cost manufacturing process that can be scaled to deposit chemically uniform ceramic coatings over arbitrarily large surface areas. BSCCO tapes have been successfully fabricated from ceramic precursor sprays pyrolyzed onto silver substrates and packaged in a silver sheath. Findings related to solution chemistry, the deposition process, tape construction, and thermomechanical processing that impact the ability to fabricate high- T c superconducting wire and tape using this technique are presented and discussed.

Environmental considerations for application of high Tc superconductors in space

Abstract High temperature superconductive materials can have significant impact in several space-based applications due to the improved electrical, magnetic, or thermal properties of the superconductive devices over existing components. However, for high temperature superconductors to be successfully applied in space-borne systems, several environmental considerations associated with spaceflight must first be addressed. The environmental factors encountered during spaceflight missions will be discussed, and a review of studies addressing the effects of these factors on the performance of the superconductive devices will be provided.