Search results for "Mars Exploration Program"
showing 10 items of 63 documents
Predicting the landslides triggered by the 2009 96E/Ida tropical storms in the Ilopango caldera area (El Salvador, CA): optimizing MARS-based model b…
2019
The main topic of this research was to evaluate the effect in the performance of stochastic landslide susceptibility models, produced by differences between the triggering events of the calibration and validation datasets. In the Caldera Ilopango area (El Salvador), MARS (multivariate adaptive regression splines)-based susceptibility modeling was applied using a set of physical–environmental predictors and two remotely recognized landslide inventories: one dated at 2003 (1503 landslides), which was the result of a normal rainfall season, and one which was produced by the combined effect of the Ida hurricane and the 96E tropical depression in 2009 (2237 landslides). Both the event inventorie…
Planning of gravimetric investigations on mars
2004
We propose to install a balance at the surface of Mars. In this paper we present a survey on tasks which could be accomplished by means of a balance. The determination of the specific surface area and porosity of Martian soil and other sorption experiments are discussed. Criteria for the choice of a suitable balance type are given.
On the accretion history of galaxy clusters: temporal and spatial distribution
2020
We analyse the results of an Eulerian AMR cosmological simulation in order to quantify the mass growth of galaxy clusters, exploring the differences between dark matter and baryons. We have determined the mass assembly histories (MAHs) of each of the mass components and computed several proxies for the instantaneous mass accretion rate (MAR). The mass growth of both components is clearly dominated by the contribution of major mergers, but high MARs can also occur during smooth accretion periods. We explored the correlations between MARs, merger events and clusters' environments, finding the mean densities in $1 \leq r/R_{200m} \leq 1.5$ to correlate strongly with $\Gamma_{200m}$ in massive …
The Origin of Life: More Questions Than Answers
1988
AbstractMore than 30 years of experimentation on the origin of life in the fields of chemical and molecular evolution have led to a better perception of the immensity of the problem of the origin of life on Earth rather than to its solution. At present all discussions on principal theories and experiments in the field either end in stalemate or in a confession of ignorance. New lines of thinking and experimentation must be tried. The continued exploration of our solar system, especially a better knowledge of Mars and Venus, of comets and carbonaceous meteorites may also lead to a better understanding of the prebiotic environment on Earth and will thus help us to design more appropriate preb…
Studies of astrophysically interesting nucleus23Al
2010
We have studied the β-delayed proton decay of 23Al with a novel detector setup at the focal plane of the MARS separator at the Texas A&M University to resolve existing controversies about the proton branching of the IAS in 23Mg and to determine the absolute proton branchings by combining our results to the latest βγ-decay data. We have made also a high precision mass measurement of the ground state of 23Al to establish more accurate proton separation energy of 23Al. Here the description of the used techniques along with preliminary results of the experiments are given.
Phononic crystals: Harnessing the propagation of sound, elastic waves, and phonons
2016
Comptes Rendus Physique - In Press.Proof corrected by the author Available online since jeudi 3 mars 2016
A view of extraterrestrial soils
2009
International audience; The nature of soils on celestial bodies other than Earth is a growing area of research in planetary geology. However, disagreement over the significance of these deposits arises in part due to the lack of a unified concept and definition of soil in the literature. The pragmatic definition “medium for plant growth” is taken by some to imply the necessity of biota for soil to exist, and has been commonly adopted in the planetary science community. In contrast, a more complex and informative definition bases on scientific theory: soil is the (bio)geochemically/physically altered material at the surface of a planetary body that encompasses surficial extraterrestrial tell…
The space age and the origin of space research
2001
The exploration of space is one of the greatest achievements of the twentieth century. In the ideal photo album of this century one could hardly avoid including such pictures as our blue planet seen from space and the human footprint on the Moon’s surface; the close-up images of a comet’s nucleus and the rough landscape of Mars; the floating of astronauts in the black vacuum around a space station and the rings of Saturn photographed from an approaching spacecraft.
Field-portable Mössbauer spectroscopy on Earth, the Moon, Mars, and beyond
2011
ABSTRACT Iron occurs naturally as Fe 2+ , Fe 3+ , and, to a lesser extent, as Fe 0 . Many fundamental (bio)geochemical processes are based on redox cycling between these oxidation states. Mossbauer spectroscopy provides quantitative information about the distribution of Fe among its oxidation states, identification of Fe-bearing phases, and relative distribution of Fe among those phases. Portable, miniaturised Mossbauer spectrometers were developed for NASA9s Mars Exploration Rovers (in operation since 2004) and provide a means for non-destructive, in-situ field investigations. On Mars, these instruments provided evidence for aqueous activity with implications for habitability, were applied…
Predicting gully occurrence at watershed scale: Comparing topographic indices and multivariate statistical models
2020
In this study, the ability of five topographic indices to predict the gully trajectories observed in two adjacent watersheds located in Sicily (Italy) was evaluated. Two of these indices, named MSPI and MTWI, as far as we know, have never been employed to this aim. They were obtained by multiplying the stream power index (SPI) and the topographic wetness index (TWI), respectively, by the convergence index (CI). The predictive ability of the topographic indices was measured by using both cut-off independent (AUC: area under the receiver operating characteristic curve) and dependent statistics (Cohen's kappa index κ, sensitivity, specificity). These statistics were calculated also for 100 MAR…