Solar signals in the minimum extreme temperature records in the southern region of the Gulf of Mexico

Minimum extreme temperature series from several meteorological stations of the Gulf of Mexico are spectrally analyzed using the Maximum Entropy Method.We obtained significant periodicities similar to those found in meteorological and solar activity phenomena. This indicates that probably the solar activity signals are present in the minimum extreme temperature records of this Mexican region.     

Subsurface filamentous fabrics: an evaluation of origins based on morphological and geochemical criteria, with implications for exopaleontology

The fossil record of the subsurface biosphere is sparse. Results obtained on subsurface filamentous fabrics (SFF) from >225 paleosubsurface sites in volcanics, oxidized ores, and paleokarst of subrecent to Proterozoic age are presented. SFF are mineral encrustations on filamentous or fibrous substrates that formed in subsurface environments. SFF occur in association with low-temperature aqueous mineral assemblages and consist of tubular, micron-thick (median 1.6 micron) filaments in high spatial density, which occur as irregular masses, matted fabrics, and vertically draped features that resemble stalactites. Micron-sized filamentous centers rule out a stalactitic origin. Morphometric analysis of SFF filamentous forms demonstrates that their shape more closely resembles microbial filaments than fibrous minerals. Abiogenic filament-like forms are considered unlikely precursors of most SFF, because abiogenic forms differ in the distribution of widths and have a lower degree of curvature and a lower number of direction changes. Elemental analyses of SFF show depletion in immobile elements (e.g., Al, Th) and a systematic enrichment in As and Sb, which demonstrates a relation to environments with high flows of water. Sulfur isotopic analyses are consistent with a biological origin of a SFF sample from a Mississippi Valley-Type deposit, which is consistent with data in the literature. Fe isotopes in SFF and active analogue systems, however, allow no discrimination between biogenic and abiogenic origins. The origin of most SFF is explained as permineralized remains of microbial filaments that possibly record rapid growth during phases of high water flow that released chemical energy. It is possible that some SFF formed due to encrustation of mineral fibers. SFF share similarities with Microcodium from soil environments. SFF are a logical target in the search for past life on Mars. The macroscopic nature of many SFF allows for their relatively easy in situ recognition and targeting for more detailed microstructural and geochemical analysis.     

The Dynamic Albedo of Neutrons (DAN) experiment for NASA's 2009 Mars Science Laboratory

We present a summary of the physical principles and design of the Dynamic Albedo of Neutrons (DAN) instrument onboard NASA's 2009 Mars Science Laboratory (MSL) mission. The DAN instrument will use the method of neutron-neutron activation analysis in a space application to study the abundance and depth distribution of water in the martian subsurface along the path of the MSL rover.     

Biomarker and stable isotope characterization of coastal pond-derived organic matter, McMurdo Dry Valleys, Antarctica

Small coastal ponds that contain photosynthetic microbial mat communities represent an extreme environment where a potentially significant source of labile organic carbon can be found within the McMurdo Dry Valleys, Antarctica. To distinguish coastal pond-derived organic matter from other sources of organic matter in the Dry Valleys, bulk organic carbon, nitrogen, and sulfur isotope signatures and phospholipid fatty acid (PLFA) profiles of benthic microbial mats located at two sites--Hjorth Hill coast and Garwood Valley--were investigated. The average isotope values at Hjorth Hill coast and Garwood Valley are, respectively, -10.9 per thousand and -10.2 per thousand for delta(13) C, 3.7 per thousand and -1.3 per thousand for delta(15)N, and 8.1 per thousand and 16.7 per thousand for delta(34)S. Microbial mats from all ponds are dominated by monounsaturated PLFAs (indicative of Gram-negative bacteria) and polyunsaturated PLFAs (indicative of microeukaryotes). Biomarkers specific to aerobic prokaryotes, eukaryotes, and photoautotrophic microeukaryotes, as well as sulfur-reducing bacteria, are present in all samples. Benthic mats at Garwood Valley are thicker and more laminated, have a higher biomass, and have a greater carbon and nitrogen content, which suggests greater productivity than mats at Hjorth Hill coast. Greater productivity is supported, as well, by higher dissolved oxygen contents likely derived from heightened photosynthetic productivity. More productivity at Garwood Valley likely results from a larger influx of terrestrial surface waters together with a concomitant nutrient loading.     

Development of a plant growth unit for growing plants over a long-term life cycle under microgravity conditions.

To study the effect of the space environment on plant growth including the reproductive growth and genetic aberration for a long-term plant life cycle, we have initiated development of a new type of facility for growing plants under microgravity conditions. The facility is constructed with subsystems for controlling environmental elements. In this paper, the concept of the facility design is outlined. Subsystems controlling air temperature, humidity, CO2 concentration, light and air circulation around plants and delivering recycled water and nutrients to roots are the major concerns. Plant experiments for developing the facility and future plant experiments with the completed facility are also overviewed. We intend to install this facility in the Japan Experiment Facility (JEM) boarded on the International Space Station.     

Super rogue wave catalysis in Titan’s ionosphere

Super rogue ion-acoustic waves are proposed as a physical catalyst for the heavy hydrocarbon ions formation in the Titan ionosphere. We justified that analytically and numerically by probing a Titan referenced plasma system, consists of the most abundant positive ions and superthermal electrons. A solution of the nonlinear Schrödinger equation (NLSE) has provided us by the plasma (un) stable regions at altitude 900–1200 km from the Titan surface with superthermal parameter values, relative ion to electron densities, and temperature ratio variations. Our results are not only agreed with the Cassini data but also predict a chemistry independent approach for the heavy hydrocarbons’ formation conditions.     

A Three-Dimensional Simulation of Collisional-Interchange-Instability in the Equatorial-Low-Latitude Ionosphere

We present a three-dimensional simulation of collisional-interchange-instability in the equatorial-low-latitude F region of ionosphere. The instability is responsible for the generation of large plasma density depletion or bubble. General 3D potential and continuity equations are derived to simulate the phenomena. To understand the linear aspect of the instability, the general 3D linear growth rate is derived using 3D potential equation. The linear growth characteristics are compared with earlier field-aligned-integrated growth analyses. The numerical simulation of bubble in the 3D spherical polar geometry is finally presented. Distinct evolution characteristics of bubble in 3D and 2D simulation are further discussed.