Search results for "astrobiology"
showing 10 items of 70 documents
High-Precision Radio Astrometry: The Search for Extrasolar Planets
2007
Background radiation effects and hazards in planetary instrumentation
2006
Recent and proposed future planetary missions are becoming increasingly concerned with detailed geochemical assessment, often in a bid to ascertain the presence of water and life supporting geochemical systems. The instruments involved may use some kind of radioactive source, e.g. X-ray fluorescence spectrometry, Mossbauer spectrometry, neutron scattering. Having radioactive sources on a lander/rover poses various potential problems, in regard to both safety to personnel involved in the building of the instrument and to radiation effects on spacecraft structure and on other instruments. Indeed background radiation effects from one instrument may dominate measurements in another resulting in…
Formation Conditions of Titan's and Enceladus's Building Blocks in Saturn's Circumplanetary Disk
2021
Abstract The building blocks of Titan and Enceladus are believed to have formed in a late-stage circumplanetary disk (CPD) around Saturn. Evaluating the evolution of the abundances of volatile species in this disk as a function of the migration, growth, and evaporation of icy grains is then of primary importance to assess the origin of the material that eventually formed these two moons. Here we use a simple prescription of Saturn’s CPD in which the location of the centrifugal radius is varied, to investigate the time evolution of the icelines of water ice, ammonia hydrate, methane clathrate, carbon monoxide, and dinitrogen pure condensates. To match their compositional data, the building b…
Extraterrestrial Mössbauer Spectroscopy
2011
To understand the origin of the Solar system and the origin of Life itself is one of the longest standing goals of human thought. Our Sun and its planets have formed out of an interstellar cloud which collapsed due to gravitational forces, forming a disk shaped so-called protosolar nebula, with the young star in the centre. Such disk shaped and dust grain containing protosolar nebulae have been observed. One of them is surrounding the young star Beta pictoris [1, 2]. Silicates, carbon and metal grains, oxides and sulfides should have been present. One of the important elements with relatively high abundance is iron. It is believed that simple molecules, such as water (H2O), carbon monoxide …
Resistance to space simulating conditions and sporicidal treatments of spores from bacilli of extreme environments origins: implication for Astrobiol…
Microorganisms able to tolerate environmental extremes, or extremophiles, are ideal candidates to extend our knowledge on the limitations for terrestrial life, including sporicidal treatments, and on their ability to survive under conditions mimicking space environments. The spore resistance of bacilli isolated from extreme environments, cold (Antarctic soils) and hot (shallow hydrothermal vents of Eolian Islands, Italy), was evaluated towards environmental stressors (wet- and dry-heat, low and high pH values), sporicidal treatments and stresses simulating space-environments (UV-C and X-rays irradiations, desiccations by low pressure, exposition to oxidizing agents and low pressure plasma),…
Water and Geodynamics
2006
Hydrogen is the most abundant element (Fig. 1⇓) in the galaxy and our solar system (Lodders 2003). Therefore it is not astonishing that hydrogen is a key player in the geodynamic evolution of planets. Its fate in the early Earth, after condensation of the solar nebula, the accretion of our planet and hydrogen reprocessing through early asteroidal and cometary bombardment (Dauphas et al. 2000) and segregation of a proto-Earth into iron core and silicate mantle is described elsewhere in this volume (Marty and Yokochi 2006). Figure 1. Abundance of elements in the solar system in numbers of atoms per 106 atoms of silicon (Lodders 2003). This chapter concerns itself with the geodynamics of the m…
The Search Starts
2010
The previous chapter has shown us that life on Earth arose surprisingly fast and easy, as soon as the conditions were right for liquid water to be sustained on the surface. We saw that there is evidence of the presence of this valuable substance in at least two other bodies in the Solar System, and these are encouraging indications that life in the Solar System might not be limited to Earth. Also, we saw that planetary systems are not rarities of nature but seem to abound across the universe, and that life is much more resistant than was once believed, which extends the limits of what can be considered a habitable world. All these facts, despite our own ignorance about many things, make num…
Looking for the origin of life in cosmochemistry : asteroids and their carbon-rich meteorites
2015
Carbonaceous chondrite meteorites are carbon-containing fragments of primitive asteroids that have offered the only samples available to date giving insights into chemical evolution in laboratory analyses. Their study has revealed that abundant organic chemistry came to be in the Solar System ahead of terrestrial life and, by the input of these meteorites and comets, might have aided in the origin of our planet’s biochemistry.
Small solar system bodies as granular systems
2017
Asteroids and other Small Solar System Bodies (SSSBs) are currently of great scientific and even industrial interest. Asteroids exist as the permanent record of the formation of the Solar System and therefore hold many clues to its understanding as a whole, as well as insights into the formation of planetary bodies. Additionally, SSSBs are being investigated in the context of impact risks for the Earth, space situational awareness and their possible industrial exploitation (asteroid mining). In all these aspects, the knowledge of the geophysical characteristics of SSSB surface and internal structure are of great importance. Given their size, constitution, and the evidence that many SSSBs ar…
Two light sensors decode moonlight versus sunlight to adjust a plastic circadian/circalunidian clock to moon phase
2021
AbstractMany species synchronize their physiology and behavior to specific hours. It is commonly assumed that sunlight acts as the main entrainment signal for ~24h clocks. However, the moon provides similarly regular time information, and increasingly studies report correlations between diel behavior and lunidian cycles. Yet, mechanistic insight into the possible influences of the moon on ~24hr timers is scarce.We studiedPlatynereis dumeriliiand uncover that the moon, besides its role in monthly timing, also schedules the exact hour of nocturnal swarming onset to the nights’ darkest times. Moonlight adjusts a plastic clock, exhibiting <24h (moonlit) or >24h (no moon) periodicity. Abun…