MEVTV Workshop on Tectonic Features on Mars

The state of knowledge of tectonic features on Mars was determined and kinematic and mechanical models were assessed for their origin. Three sessions were held: wrinkle ridges and compressional structure; strike-slip faults; and extensional structures. Each session began with an overview of the features under discussion. In the case of wrinkle ridges and extensional structures, the overview was followed by keynote addresses by specialists working on similar structures on the Earth. The first session of the workshop focused on the controversy over the relative importance of folding, faulting, and intrusive volcanism in the origin of wrinkle ridges. The session ended with discussions of the origin of compressional flank structures associated with Martian volcanoes and the relationship between the volcanic complexes and the inferred regional stress field. The second day of the workshop began with the presentation and discussion of evidence for strike-slip faults on Mars at various scales. In the last session, the discussion of extensional structures ranged from the origin of grabens, tension cracks, and pit-crater chains to the origin of Valles Marineris canyons. Shear and tensile modes of brittle failure in the formation of extensional features and the role of these failure modes in the formation of pit-crater chains and the canyons of Valles Marineris were debated. The relationship of extensional features to other surface processes, such as carbonate dissolution (karst) were also discussed

Rock size‐frequency distributions on Mars and implications for Mars Exploration Rover landing safety and operations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95449/1/jgre1686.pd

Present-day Mars' seismicity predicted from 3-D thermal evolution models of interior dynamics

©2018. American Geophysical UnionThe Interior Exploration using Seismic Investigations, Geodesy and Heat Transport mission, to be launched in 2018, will perform a comprehensive geophysical investigation of Mars in situ. The Seismic Experiment for Interior Structure package aims to detect global and regional seismic events and in turn offer constraints on core size, crustal thickness, and core, mantle, and crustal composition. In this study, we estimate the present‐day amount and distribution of seismicity using 3‐D numerical thermal evolution models of Mars, taking into account contributions from convective stresses as well as from stresses associated with cooling and planetary contraction. Defining the seismogenic lithosphere by an isotherm and assuming two end‐member cases of 573 K and the 1073 K, we determine the seismogenic lithosphere thickness. Assuming a seismic efficiency between 0.025 and 1, this thickness is used to estimate the total annual seismic moment budget, and our models show values between 5.7 × 1016 and 3.9 × 1019 Nm

Quasi-ballistic transport in HgTe quantum-well nanostructures

The transport properties of micrometer scale structures fabricated from high-mobility HgTe quantum-wells have been investigated. A special photoresist and Ti masks were used, which allow for the fabrication of devices with characteristic dimensions down to 0.45 $\mu$m. Evidence that the transport properties are dominated by ballistic effects in these structures is presented. Monte Carlo simulations of semi-classical electron trajectories show good agreement with the experiment.Comment: 3 pages, 3 figures; minor revisions: replaced "inelastic mean free path" with "transport mean free path"; corrected typing errors; restructered most paragraphs for easier reading; accepted for publication in AP

Re-conceptualizing Teachers’ Narrative Inquiry as Professional Development

We offer a more nuanced characterization of teachers’ narrative inquiry as professional development (Johnson and Golombek, 2002) by grounding our definition of and empirical research on teachers’ narrative inquiry from a Vygotskian sociocultural theoretical perspective. Our goal is to reaffirm our belief in the educational value of teachers’ narrative inquiry as “systematic exploration that is conducted by teachers and for teachers through their own stories and language” (p. 6), while empirically documenting the crucial role of teacher educators in creating mediational spaces, dialogic interactions, and pedagogical tools for teachers’ narrative inquiry to flourish as professional development. It is also our goal to re-conceptualize teachers’ narrative inquiry as unbounded by time and place, and as a more fluid and emerging process.Ofrecemos una caracterización más detallada del uso de las indagaciones narrativas de los docentes para su desarrollo profesional (Johnson y Golombek, 2002), para lo cual basamos nuestra definición de y la investigación empírica sobre la investigación narrativa de los docentes en la teoría sociocultural de Vygostky. Nuestro propósito consiste en reafirmar nuestra convicción acerca del valor educativo de la investigación narrativa de los docentes como una “exploración sistemática que es conducida por y para los docentes por medio de sus propios relatos y lenguaje” (p. 6). Asimismo, documentamos de manera empírica el papel crucial de los formadores de docentes para crear espacios mediacionales, las interacciones dialógicas y herramientas pedagógicas que promuevan la indagación narrativa de los docentes como forma de desarrollo profesional. También pretendemos re-conceptualizar la indagación narrativa de los docentes como un proceso sin limitantes de tiempo y espacio, y con una naturaleza fluida y emergente

The transformative power of narrative in second language teacher education.

Within the field of second language teacher education (SLTE), narrative has largely functioned as a vehicle for teacher inquiry, based on the assumption that such inquiry will ultimately bring about productive change in teachers and their teaching practices. Less attention has been paid to documenting what this change looks like or how engagement in narrative activities fosters teacher professional development. From a Vygotskian sociocultural theoretical perspective, we argue that the transformative power of narrative lies in its ability to ignite cognitive processes that can foster teacher professional development. We tease out the complex ways in which narrative functions as a mediational tool-narrative as externalization, verbalization, and systematic examination-in fostering teacher professional development, and we highlight the interplay between these functions by tracing teacher professional development in two teacher-authored narrative inquiries. We then turn to the centrality of narrative as a vehicle for teacher inquiry in transforming the field of SLTE itself. Specifically, we highlight various outlets, in both center and periphery contexts, where the products of teachers' narrative activities are functioning as a tool for knowledge-building and professional development practices that are working in consort to transform the professional landscape that constitutes the field of SLTE

Small crater modification on Meridiani Planum and implications for erosion rates and climate change on Mars

A morphometric and morphologic catalog of ~100 small craters imaged by the Opportunity rover over the 33.5 km traverse between Eagle and Endeavour craters on Meridiani Planum shows craters in six stages of degradation that range from fresh and blocky to eroded and shallow depressions ringed by planed off rim blocks. The age of each morphologic class from <50–200 ka to ~20 Ma has been determined from the size‐frequency distribution of craters in the catalog, the retention age of small craters on Meridiani Planum, and the age of the latest phase of ripple migration. The rate of degradation of the craters has been determined from crater depth, rim height, and ejecta removal over the class age. These rates show a rapid decrease from ~1 m/Myr for craters <1 Ma to ~ <0.1 m/Myr for craters 10–20 Ma, which can be explained by topographic diffusion with modeled diffusivities of ~10^(−6) m^2/yr. In contrast to these relatively fast, short‐term erosion rates, previously estimated average erosion rates on Mars over ~100 Myr and 3 Gyr timescales from the Amazonian and Hesperian are of order <0.01 m/Myr, which is 3–4 orders of magnitude slower than typical terrestrial rates. Erosion rates during the Middle‐Late Noachian averaged over ~250 Myr, and ~700 Myr intervals are around 1 m/Myr, comparable to slow terrestrial erosion rates calculated over similar timescales. This argues for a wet climate before ~3 Ga in which liquid water was the erosional agent, followed by a dry environment dominated by slow eolian erosion

ExoMars entry, descent and landing science

The entry, descent and landing of ExoMars offer a rare (once-per-mission) opportunity to perform in situ investigation of the martian environment over a wide altitude range. Entry, Descent and Landing System (EDLS) measurements can provide essential data for atmospheric scientific investigations. We intend to perform atmospheric science measurements by exploiting data from EDLS engineering sensors and exploiting their readings beyond the expected engineering information

In Situ Investigation of Iron Meteorites at Meridiani Planum Mars

The Mars Exploration Rover Opportunity has encountered four iron meteorites at its landing site in Meridiani Planum. The first one, informally named "Heat Shield Rock", measuring approx.30 by 15 cm, was encountered in January 2005 [1, 2] and officially recognized as the first iron meteorite on the martian surface with the name "Meridiani Planum" after the location of its find [3]. We will refer to it as "Heat Shield Rock" to avoid confusion with the site. Between July and October 2009, separated approx.10 km from Heat Shield Rock, three other iron meteorite fragments were encountered, informally named "Block Island" (approx.60 cm across), "Shelter Island" (approx.50 by 20 cm), and "Mackinac Island" (approx.30 cm across). Heat Shield Rock and Block Island, the two specimens investigated in detail, are shown in Figure 1. Here, we focus on the meteorites chemistry and mineralogy. An overview in the mission context is given in [4]; other abstracts discuss their morphology [5], photometric properties [6], and their provenance [7]