20 research outputs found
The Mistastin Lake Impact Structure As A Terrestrial Analogue Site For Lunar Science And Exploration
The impact cratering record on the Moon is important for many reasons, from understanding early solar system chronology to probing the lunar interior. In order to maximize scientific return from future lunar missions, it is useful to: 1) study terrestrial impact craters to better understand impact processes and products, and 2) develop appropriate human and robotic exploration strategies aligned with geological goals.
This research shows that the intermediate-size Mistastin Lake impact structure, in northern Labrador, Canada, is an unparalleled lunar analogue site, which includes both an anorthositic target and an almost complete suite of impact lithologies, including proximal ejecta deposits. New remote sensing, field mapping, and microscopy data are used to develop new structural and geological models of the Mistastin Lake impact structure. The results of this study show that a multi-stage ejecta emplacement model is required to explain the observations. It is also shown that impact melt-bearing breccias or “suevites” at Mistastin were emplaced as flows, were never airborne, and were formed from the mixing of impact melt flows with underlying lithic materials.
In order to maximize scientific return from future lunar missions, this work also focused on developing appropriate human and robotic exploration strategies aligned with geological goals. We show that precursor reconnaissance missions provide surface geology visualization at resolutions and from viewpoints not achievable from orbit. Within such a mission concept, geological tasks are best divided between fixed-executional approaches, in which tasks are fairly repetitive and are carried out by an unskilled surface agent, and an adaptive-exploratory approach, where a skilled agent makes observations and interpretations and the field plan can adapt to these findings as the agent progresses. Operational considerations that help increase scientific return include: extensive pre-mission planning using remote sensing data; defining flexible plans and science priorities to respond to changing conditions; including mutually cross-trained scientists and engineers on the field team; and adapting traverses to accommodate field crew input and autonomy. A phased approach for human exploration proved successful in incorporating astronaut feedback and allowed more autonomy for astronauts to determine optimal sampling localities and sites for detailed observations
The Northern HIPASS catalogue - Data presentation, completeness and reliability measures
The Northern HIPASS catalogue (NHICAT) is the northern extension of the
HIPASS catalogue, HICAT (Meyer et al. 2004). This extension adds the sky area
between the declination range of +2 deg < dec. < +25.5 deg to HICAT's
declination range of -90 deg < dec. < +2 deg. HIPASS is a blind HI survey using
the Parkes Radio Telescope covering 71% of the sky (including this northern
extension) and a heliocentric velocity range of -1,280 km/s to 12,700 km/s .
The entire Virgo Cluster region has been observed in the Northern HIPASS. The
galaxy catalogue, NHICAT, contains 1002 sources with v_hel > 300 km/s . Sources
with -300 km/s < v_hel < 300 km/s were excluded to avoid contamination by
Galactic emission. In total, the entire HIPASS survey has found 5317 galaxies
identified purely by their HI content. The full galaxy catalogue is
publicly-available at .Comment: 12 pages, accepted for publication by MNRA
A mission control architecture for robotic lunar sample return as field tested in an analogue deployment to the Sudbury impact structure
A Mission Control Architecture is presented for a Robotic Lunar Sample Return Mission which builds upon the experience of the landed missions of the NASA Mars Exploration Program. This architecture consists of four separate processes working in parallel at Mission Control and achieving buy-in for plans sequentially instead of simultaneously from all members of the team. These four processes were: Science Processing, Science Interpretation, Planning and Mission Evaluation. Science Processing was responsible for creating products from data downlinked from the field and is organized by instrument. Science Interpretation was responsible for determining whether or not science goals are being met and what measurements need to be taken to satisfy these goals. The Planning process, responsible for scheduling and sequencing observations, and the Evaluation process that fostered inter-process communications, reporting and documentation assisted these processes. This organization is advantageous for its flexibility as shown by the ability of the structure to produce plans for the rover every two hours, for the rapidity with which Mission Control team members may be trained and for the relatively small size of each individual team. This architecture was tested in an analogue mission to the Sudbury impact structure from June 6-17, 2011. A rover was used which was capable of developing a network of locations that could be revisited using a teach and repeat method. This allowed the science team to process several different outcrops in parallel, downselecting at each stage to ensure that the samples selected for caching were the most representative of the site. Over the course of 10 days, 18 rock samples were collected from 5 different outcrops, 182 individual field activities - such as roving or acquiring an image mosaic or other data product - were completed within 43 command cycles, and the rover travelled over 2,200 m. Data transfer from communications passes were filled to 74%. Sample triage was simulated to allow down-selection to 1kg of material for return to Earth
Komplexe Deformitaeten im Bereich des Unterarmes: Operative Behandlungsstragie bei posttraumatischer Pathologie
From genesis to juxtaposition: the evolution of the Ivisârtoq greenstone belt, southwest Greenland
The Ivisârtoq greenstone belt is situated ~40 km south of the Isua greenstone belt within the Godthåbsfjord region of southwest Greenland. This region is part of the Archean gneiss complex of Greenland, a major component of the 3800-2500 Ma North Atlantic Craton. Compared to the Isua greenstone belt, which has been the focus of intense study because it contains some of the oldest known (~ 3.8-3.7 Ga) rocks on Earth, little work has been carried out on the Ivisârtoq greenstone belt. The Ivisârtoq greenstone belt is exceptionally well-exposed in three dimensions with relief of 1200m, and primary features are better preserved here than in any other Archean greenstone belt in Greenland. Consequently, this belt provides an exceptionally good opportunity to characterise early to middle Archean magmatism, deformational processes, and tectonic environments. -- The Ivisârtoq greenstone belt was multiply deformed and metamorphosed at amphibolite facies. The belt forms an upright southwest-closing, V-shaped synform. This study concentrated on the 3 km thick southern limb of the synform, where the most complete section of the supracrustal rocks is preserved, and where there are pillow lava structures with way-up indicators. The southern limb was found to comprise a tectonostratigraphy made up of two main components, termed the northern and southern parts. These composite rock units differ in composition and intensity of deformation and are separated by a major high strain zone. -- The northern part of the belt is generally less deformed than the southern part and is characterized by heterogeneously deformed amphibolite, derived from variolitic and homogeneous basaltic pillow lavas, interlayered with boudins of olivine-bearing ultramafic rocks and quartz-feldspar-mica gneiss and schist. The southern part consists predominantly of strongly deformed rocks including banded amphibolite, homogeneous granitoid, gabbroic rocks, and a thick layer of predominantly quartz-feldspar-biotite- schist. -- New major and trace element geochemical data, LAM ICP-MS U-Pb zircon geochronology, and field mapping have shed new light on the origin and evolution of the Ivisârtoq greenstone belt. This new work indicates that the northern and southern parts of the belt represent discrete packages of rocks that formed in different environments and were juxtaposed after -2895 Ma, after the main volcanism associated with each part had ceased. Each package of rocks suffered separate deformational events before juxtaposition: two discrete deformational phases were recognized in the less deformed northern part, whereas the southern part was much more intensely deformed and individual events could not be differentiated. -- Crustal contamination signatures of the amphibolites in the northern part of the belt suggest formation in a back-arc basin environment, in which the basaltic magma ascended through thin, patchy or immature crust. A U-Pb zircon age of an intrusive tonalite sheet demonstrates that the northern basaltic pillow lavas were deposited before -3165 Ma. -- In contrast, the southern part of the belt appears to have formed on a thick continental crust. This interpretation is based on several lines of evidence: crustal contamination signatures of the banded amphibolite, the presence of a thick sequence of quartzofeldspathic metasedimentary rocks, an A-type granitoid, and a horizon of metamorphosed meymechite, which is indicative of deep melting of subcontinental mantle. A maximum age of-2895 Ma was determined for the deposition of the southern metasedimentary rocks. -- The interpreted juxtaposition of the northern and southern packages of the Ivisârtoq belt is consistent with lateral collisions of terranes perhaps by plate tectonic processes
Stereotactic implantation of cysto-ventricular catheters in patients with craniopharyngeomas: An effective method to control cyst size and improve conditions for radiotherapy
Persistence of foodborne pathogens and their control in primary and secondary food production chains
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