Arcetri Astrophysical Observatory

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Planetology and Astrobiology



Astrobiology is the study of the origin, evolution and distribution of life in the Universe. It's a multidisciplinary science that benefits from the knowledge and skills that come from disciplines until now considered to belong to distinct areas such as biology, chemistry, astrophysics, geology and genetics.

The presence of life on Earth is directly related to both the origin and evolution of the Solar System and the initial conditions in the molecular cloud from which we originated. The life as it is known on Earth originated from complex chemical reactions, likely outcome of the interaction of organic molecules and inert material coming from space.

Therefore, in this context, we deal with the study in laboratory of chemical and physical mechanisms of synthesis and evolution of organic matter by interactions with the surfaces of minerals, photons and energetic particles. In addition, we study in the laboratory the nature of extraterrestrial material such as meteorites, interplanetary dust particles or samples brought back to Earth from space missions.

In recent years, planetary science has been able to give a more accurate description of the Solar System by means of observations made by Earth-based telescopes but also thanks to space exploration of planets, asteroids and comets. We study, therefore, the nature of comets and asteroids through spectroscopic and images analysis obtained from ground-based telescopes and from space missions. 

RESEARCH ACTIVITY

Astrobiology

Copia di Lab 1

The research activity is centered on the study of the physical-chemical properties of dust present in the space and of the interactions between the surfaces of solids and the biomolecules in simulated space conditions. The organic molecules in contact with small solid are not inert. Various causes such as different space environments or surfaces may promote physical and chemical reactions giving rise to new materials. Our scientific objectives are, therefore, the laboratory simulation of chemical and physical processes active in the solar system and in the interstellar medium that drive the formation and evolution of organic compounds. In the laboratory are, therefore, synthesized prebiotic molecules in order to understand the basic mechanisms that have enabled the origin of life on Earth and probably in space. Analogs of cosmic dust as the amorphous and crystalline silicates and carbonaceous materials, are synthesized in the laboratory using various techniques such as laser ablation, electron beam and arc discharge getting different grain morphologies, porous or compact or thin films with amorphous or crystalline structure. We study, therefore, the catalytic effects of the surfaces in the synthesis of biomolecules in solid, liquid and gas phase by means of various techniques such as synchrotron radiation, Raman spectroscopy, UV-Vis-IR both macro and micro, scanning electron microscopy (SEM), mass spectroscopy and liquid chromatography.

This type of research is also a fundamental support for the development of scientific instruments on board space missions such as ExoMars. In fact, the knowledge of how biomolecules are adsorbed and desorbed from mineral surfaces or what is the nature of the interactions between them, allows us to develop techniques and protocols that bioanalytical tools developed for the space will be used to reveal potential signs of life on Mars (Life Marker Chip, MOMA).

Another important aspect is the presence of water in space. In the Solar System, the water in the solid state is found on planets and small bodies such as comets, trans-Neptunian objects, centaurs and asteroids. Although water is the main constituent of the ice present in the interstellar medium, its chemical origin is not well understood. For this reason we study the formation of water on the surfaces of dust grains, by means of reaction with the hydrogen and atomic oxygen in the gas phase. This activity is conducted in collaboration with the Department of Physics, University of Syracuse, New York U.S..

Another activity concerns the study of the chemical and mineralogical composition of meteorites, interplanetary dust (IDPs) and the grains of comet Wild 2 returned to Earth by NASA's Stardust spacecraft. With this in mind we are working on an ambitious goal to bring back to the ground and analyze fragments of primitive carbon-rich asteroids through ESA missions MarcoPolo-R and NASA's OSIRIS-REx and to collect samples from the Martian moons Phobos and Deimos with the ESA mission PHOOTPRINT.

Comets

The main activity is the study of the comets and their astrobiological importance to the possible delivery on the primordial Earth of the building blocks from which the life formed. In particular we search for grains of organic matter that may be present in the coma of comets, especially in the new ones at they first passage in the inner solar system. The research consist in the selection of interesting comets, their observations and the analysis and interpretation of the the data.

The observations consist usually in image and spectra of the coma in the visible and near-IR. For some very interesting comets, as for example the C/1995 O1 (Hale-Bopp), the observations have covered a very wide spectral range: from the radio domain, with Medicina radio-telescope, to the X-rays, with Beppo-Sax. Often polarimetric observations are also done, to confirm the presence of organic grains.

Recently, with the availability of robotic telescopes as the 1.23 m at Calar Alto (E) and the Liverpool Telescope in La Palma (E), we started a program of monitoring new comets coming from the Oort cloud. The beginning of the observations should start as early as possible, when the comets is far from the Sun (heliocentric distance greater than 5-6 AU). And it is necessary to follow the comets periodically, during their approach to the Sun. Since such comets are supposed to have a layer of organic matter on the surface, produced by billion years of space weathering, the observations of the coma evolution with the increase of the solar radiation, allow us to check the presence of this layer and other possible stratification of the nuclei. In this context positive and interesting results have been obtained with the comets C/2011 F1 (LINEAR) and the C/2012 S1 (ISON).


A great part of the activity is now devoted to the Rosetta mission, a ESA cornerstone mission to the comet 67P (Churyumov–Gerasimenko)‎. The spacecraft will reach the comet in May 2014 and, few months later, it will release for the first time ever a lander to the comet nucleus. The spacecraft will continue to observe the comet before and after the peri-helion. The mission is supposed to give a quantum leap on our knowledge of comets and their importance to the formation of life on the Earth. We are part of the VIRTIS team, a spectrograph on-board Rosetta covering a spectral range from the UV to 5 micron, capable to take spectral cube of the neleus surface and the coma.

Asteroids

The study of minor bodies of our Solar System, and in particular the asteroids, has experienced an intense development over the last decade. Asteroids are an interdisciplinary topic that not only concerns Astronomy, Astrophysics and Celestial Mechanics, but also Geology, Mineralogy and Physics of Materials. Recent studies have highlighted the extreme complexity of the physical mechanisms that underlie the formation and evolution of these objects, leading to large changes of paradigm in the interpretation of observational data.

Theoretical researches concerining the collisional evolution of asteroids are conducted at the Observatory of Arcetri. The gravitational perturbations of the planets of the Solar System produce continuous changes, on astronomical time scales, on the orbits of the asteroids, which in turn determine the possibility of orbital intersections and collisions between those bodies. In the Main Belt (the part of the Solar System between the orbits of Mars and Jupiter in which the large majority of asteroids reside) collisions among asteroids at velocities of the order of 5 km/s occur for billions of years. These collisions cause the fragmentation of these bodies and the formation of groups of new bodies (the fragments) observed today as dynamic groups of asteroids with orbits very similar (Asteroid Families). The goal of the research is to understand how the overall characteristics of the population evolve, and in particular the size distribution and periods of rotation. To achieve this result a deep knowledge of the statistics of collisions and the physics of fragmentation is needed.

In recent years it has been shown that the evolution of asteroids is dominated not only by the mutual collisions, but also by non-gravitational dynamical effects, as the Yarkovsky effect and the YORP effect. These mechanisms of surface heating by of the solar radiation and the subsequent re-emission of thermal radiation, in combination with the intrinsic rotation of asteroids, are able to modify appreciably the orbits and rotation of the same objects. These effects, together with the planetary perturbations, play a crucial role in the transfer of asteroids from the Main Belt to the region of the inner planets, i.e. with respect to the formation of asteroids with orbits similar to Earth's (Near Earth Asteroids). All these issues are studied in a single framework that links the physics of impact and fragmentation (investigated both in laboratory and with theoretical models) with the dynamics of the Solar System and the physics of the interaction of radiation with matter.

Finally, the Observatory is involved in the preparation of the Gaia space mission. Although Gaia has been mainly designed for the study of the structure of our Galaxy, it will observe about half a million asteroids. Thanks to its enormous astrometric precision, Gaia will provide us measurements of the orbits of asteroids so accurate to allow to detect the effects of their mutual gravitational perturbations, from which the mass of a hundred asteroids will be estimated with errors less than 30% (and for the largest ones below 10%). In addition, on the basis of the disk-integrated photometry it will be possible to determine the periods of rotation and the direction of the axes (as well as information about the shape) for tens of thousands of asteroids. Gaia will contribute to the study of minor bodies, even indirectly, after the end of mission. Thanks to the precision in determining the orbits will be possible to significantly increase the number of ground-based observations of stellar occultations by asteroids, from which to obtain direct measurements of the size of the objects. Moreover, thanks to the accuracy in the determination of the positions and proper motions of the stars near the Sun, it will be possible to carry out detailed studies about the interaction between the interstellar environment and the Oort cloud, with great impacts on the study of comets.


TEAM (Phone: +39 055 2752 xxx)

NameE-mailDirect

John Robert Brucato
Gian Paolo Tozzi
Aldo dell'Oro
Patrizio Patriarchi
Eugenio Simoncini
Stefano Pellari
Teresa Fornaro
Sara Faggi

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