Vie extraterrestre

Résumé

La vie extraterrestre (du latin extra, « au-dehors, à l'extérieur »), ou extra-terrestre, désigne toute forme de vie présente ailleurs que sur la planète Terre. vignette|La météorite de Murchison intéresse particulièrement les astrophysiciens, les cosmochimistes et les exobiologistes à la recherche des origines de la vie, son étude ayant fortement influencé la thèse sur l'origine extraterrestre de la vie sur Terre. L'idée que la vie puisse se développer ailleurs dans l'Univers remonte au moins à l'Antiquité. La mise en évidence d'une vie extraterrestre, présente ou passée, est un sujet de recherche scientifique actif depuis les années 1980, après une première tentative de recherche d'indices par les sondes spatiales du programme Viking envoyées sur le sol de la planète Mars en 1975. Depuis la fin des années 1990, la NASA poursuit un programme d'exploration spatiale très actif visant à mettre en évidence des indices de vie sur Mars, présente ou fossile : analyse poussée des sols (ast

Source officielle

https://fr.wikipedia.org/wiki/Vie_extraterrestre

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The main objective of the course is to introduce the concept of space system design and engineering. The course will describe the various subsystems involved in the design of a satellite. It will also describe the techniques of systems engineering that are used to obtain a coherent satellite design.

Diversité du monde vivant, rôle et action des Procaryotes dans la biosphère. Fonctionnement biochimique des êtres vivants comprenant les voies métaboliques centrales et les fonctions des biomolécules majeures. Rôle central joué par l'information génétique, des mécanismes évolutifs et de régulation.

Ce cours traite des divers domaines techniques intervenant dans la conception et la réalisation d'un bâtiment, soit : physique du bâtiment, structures, matériaux, construction et installations techniques; ceci dans une approche globale et transversale.

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Science, Democracy, and the Pursuit of Aliens

Jérôme Baudry

In 1902, a contributor to Popular Science affirmed that “The era of the amateur scientist is passing; science must now be advanced by the professional expert.” Throughout the twentieth century, amateurs have been increasingly excluded from the production of scientific knowledge. But since the 1990s, under the banner of “citizen science”, a growing number of initiatives have involved, once again, amateurs in science, with the goal of democratizing science, promoting scientific literacy, and solving big data problems. The creation of SETI@home at UC Berkeley in 1998 embodied all these aims. Within six month, it had attracted more than one million participants analyzing radio signals from space on their personal computer searching for signs of extraterrestrial life. The initiators of the project and the media constructed the image of the participant along the lines of an imagined amateur scientist making discoveries outside of scientific institutions, while contributing to the making of a global scientific citizenship. Infused by libertarian, countercultural, and cyber-utopian ideals, SETI@home seemed to capture the scientific aspirations of a new generation. But the tens of thousands of online biographical sketches left by the participants present a more nuanced picture. These traces offer a unique window into the self-fashioning of the participants into different kinds of “amateurs”, “volunteers”, and “hobbyists” with various views about professional science and its place in society. These sources helps us better understand the recent reconfigurations of the amateur scientist and, more generally, the struggles over the legitimacy of professional expertise.

2019

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On the adjustment, calibration and orientation of drone photogrammetry and laser-scanning

Emmanuel Pierre Quentin Clédat

Centimetre level precision mapping is essential for many applications such as land-use, infrastructure inspection, cultural heritage preservation, and construction site monitoring. However, the acquisition and its preparation (in particular the setting of a ground control point network (GCPs)) are still expensive or even impossible in cluttered or dangerous areas. The recent development of UAVs together with the miniaturization of the sensors is a promising evolution for reducing costs and expand opportunities. The sensors embedded on the drone: GNSS antenna, IMU, camera and (optional) LIDAR are light and often low-cost. The low quality of their raw measurements must be counterbalanced by their rigorous modeling in order to obtain accurate final results: if we cannot expect the sensors to be error-free, one must model these in order to correct them. This is achieved by in-situ calibration or on a dedicated calibration field, together with a rigorous fusion of the raw data acquired by the different sensors with the so-called bundle-adjustment method. This thesis proposes several models to describe the behavior of the sensors, in order to hybridize them rigorously in the bundle-adjustment. Consistent datasets have been acquired on the field specifically to assess the relevance of both the sensor models and their hybridizing in complex photogrammetric processing. The contribution of this thesis could be divided into two mains categories. On one hand, this thesis suggests tools and recommendation to improve directly the procedures achieved by end-users using current UAV-mapping commercial solutions (in particular for the GCPs placement, for the choice of the camera calibration and model and for the flight-plan). On the other hand, this thesis put forward exotic methods (methods considered as exotic at the time of the writing of the thesis) such as Photo-LIDAR hybridizing and collaborative mapping achieved by a terrestrial-aerial tandem (a terrestrial vehicle holding a LIDAR, GNSS, imaging and inertial sensors followed by a drone conceived to proceed to airborne photogrammetry) or an aerial-aerial tandem (two drones flying in formation to proceed to airborne photogrammetry). The contribution of this thesis will permit to reduce costs, to improve the quality of mapping products and to enlarge the possibilities of mapping: in particular, map cluttered or inaccessible zones which are nowadays considered as difficult or even impossible to map.

EPFL2020

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The cryosphere includes those parts of Earth where water or soil is frozen, such as snow, ice, glaciers and permafrost soils. Here, the authors present a global inventory of cryospheric microbial communities and their genetic repertoires. The melting of the cryosphere is among the most conspicuous consequences of climate change, with impacts on microbial life and related biogeochemistry. However, we are missing a systematic understanding of microbiome structure and function across cryospheric ecosystems. Here, we present a global inventory of the microbiome from snow, ice, permafrost soils, and both coastal and freshwater ecosystems under glacier influence. Combining phylogenetic and taxonomic approaches, we find that these cryospheric ecosystems, despite their particularities, share a microbiome with representatives across the bacterial tree of life and apparent signatures of early and constrained radiation. In addition, we use metagenomic analyses to define the genetic repertoire of cryospheric bacteria. Our work provides a reference resource for future studies on climate change microbiology.

NATURE PORTFOLIO2022

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On the adjustment, calibration and orientation of drone photogrammetry and laser-scanning

Emmanuel Pierre Quentin Clédat

EPFL2020