Binary asteroids are key objects to understanding the intimate internal nature of asteroids as for them, it is possible to compute the total mass and the bulk density. The formation itself of asteroid satellites can be the result of collisions, fission and rotational spin up, whose issue depends on the internal structure. However, the currently known sample of binaries is heavily biased by the currently available techniques, ad a whole range of possible separation / sizes has remained inaccessible up to now. In GaiaMoons we will exploit the ultra-accurate astrometry of forthcoming data releases by the Gaia mission, to discover a large number of Main Belt binaries belonging to this unknown population, and to better characterise the known ones. The new approach consists in measuring the astrometric perturbation induced by the presence of a satellite. With the additional information provided by photometry and Gaia spectroscopy, we will determine their physical properties (mass, density), the orbital parameters of the companion, and the composition. In turn, composition and density will allow us to constraint the asteroid internal porosity, thus discriminating between the compact or fragmented internal structure inherited from the evolution history. We also exploit data obtained so far by stellar occultations, and observe new events to obtain an independent validation of our discoveries. Our project is based on a collaboration between experts of Gaia at the Observatoire de la Côte d'Azur, specialists in occultation techniques at Observatoire de Paris and in photometry at the University of Poznan.

The small bodies of the Solar System are primordial bricks of the formation of our planetary system. For the last decade, Earth-ground, space and in-situ observations have opened a golden age for their study, motivated by the need to understand these witnesses of the first ages of the Solar System and by the unexpected discovery of rings. These primitive bodies have evolved since their formation. In order to make the link between current observations and the origin of the Solar System, this project aims to develop detailed and varied 3D models of the internal structure and shape of asteroids (mainly binaries) as well as large TNOs. The goal will then be to study the link between formation and evolution of these protoplanets, in particular through an accurate modeling of dissipative effects for the case of binary systems. A particular attention will be paid to the introduction of tides in small bodies and the Didmos-Dimorphos system targeted by DART (NASA) and HERA (ESA). Finally, the discovered rings are surprising by their existence but in addition, one of the rings is located beyond the Roche limit where the ring should accrete into a satellite. This project will therefore address these issues. An emblematic case will be the study of Haumea which offers the possibility to study processes such as differentiation, collision, and ring formation. In the case of NEOs, knowledge of the internal structure will also provide information for planetary defense.

According to Milankovitch (1941) theory, some of the large climatic changes of the past originate in the variations of the Earth’s orbit and of its spin axis resulting from the gravitational pull of the other planets. These variations can be traced over several millions of years (Ma) in the geological sedimentary records, although the mechanisms that transfer the forcing insolation to the sedimentary variations are not precisely known. After the pioneer work of Hays et al (1976), a large effort of the stratigraphic community has been devoted to the search of this astronomical imprint. Over the last three decades, the Earth’s orbital and spin solutions elaborated by the PI and his group (Laskar et al, 1993, 2004, 2011a) have been used in a collaborative effort that allowed to establish for the Neogene (0-23Ma) a geological timescale based on the astronomical solution (Lourens et al, 2004; Hilgen et al, 2012). Nevertheless, extending this procedure through the Mesozoic Era (66-252 Ma) is difficult, as the solar system motion is chaotic (Laskar, 1989, 1990). It will thus not be possible to retrieve the precise orbital motion of the planets beyond 60 Ma from their present state (Laskar et al, 2011b). For three decades, the astronomical orbital solutions elaborated by the PI have been used by geologists to establish local or global time scales. This project is specifically designed to achieve the opposite. We will use the geological record as an input to break the horizon of predictability of 60Ma which results from the chaotic nature of the orbital motion of the planets. This will be done in a quantitative manner, and aims to provide a template orbital solution for the Earth that could be used for paleoclimate studies over the Mesozoic Era. This will open a new era where the geological record will actually be used to retrieve the orbital evolution of the solar system. This project stems from the achievement of Olsen et al (2019) where for the first time, in a study that involves the PI, it was possible to precisely recover the frequencies of the precessing motion of the inner planets (http://www.cnrs.fr/en/when-geology-reveals-solar-systems-past-secrets). At the same time, numerous studies appear involving very long sedimentary records (Ma et al, 2017, 2019). The objectives that many have dreamed for twenty years are thus now at hand. AstroMeso aims to go one step beyond by gathering a unique team with world leaders in celestial mechanics and planetary motions and world leaders in cyclostratigraphic analysis of long sedimentary records. AstroMeso will support two postdocs. One in astronomy for the search of an optimal orbital and insolation solution, and the other in geology, who will collect and analyse the best records. Both will work in close connection with the teams of the project, maintaining a strong interaction between astronomy and geology all along the duration of the project. This interdisciplinary, necessarily interdisciplinary, project, between geology and astronomy, searching to retrace the history of the Earth and the solar system trough the geological record, fits perfectly with the INSU-CNRS will to develop transversality around fundamental questions.

The core of the FRIPON project (Fireball Recovery and Planetary Inter Observation Network) is to (i) determine the source regions of the various meteorite classes, (ii) collect both fresh and rare meteorite and (iii) perform scientific outreach. This will be achieved by building the densest camera network in Europe, based on state of the art technologies and associated with a participative network for meteorite recovery. The present project aims to covering the cost of setting up this network, which will be achieved over the next 3 years. However, our goal is to make it sustainable for at least 10 years. The only way for determining the source regions of meteorites is to witness the falls live to derive their orbits. We propose to install a network of 100 digital cameras covering the entire French territory. It will use the most recent technology: to get orbital elements with unprecedented accuracy, we will use radio receivers to measure the Doppler effect generated by the GRAVES radar echo on the meteor head. Accurate orbits of the bolides will allow us to (i) constrain their source region and (ii) compute impact locations with a ~1 km accuracy (giving us a real chance of recovering the meteorites). We need about one thousand orbits to start statistical work for meteorite source detection. This goal will be achieved within 3 years as there is on average one bolide per night over France. In addition, considering that there are 5 to 25 falls over France per year (~15 on average), during the 10 years life of the project, there will be ~150 falls out of which we realistically expect to recover ~30 fresh meteorites including 4 to 8 important ones (i.e. not ordinary chondrites), based on fall statistics. Regional centers (mostly scientific laboratories) will form the basis of our network as they will be responsible for ~4-5 video cameras and one radio receiver. Aside from these laboratories, cameras will be installed in all kinds of public structures. All cameras images will be made available to the public. After each ‘event’, the core team will decide, upon analysis of the fireball parameters, whether or not to organize a recovery campaign. Once our network is fully operational, we will cooperate with our colleagues in the adjoining countries by (i) providing them with data on relevant falls and (ii) exporting the expertise developed in France to expand the network. Finally, as our network will be designed to require a minimum of maintenance, we foresee operations for about 10 years with minimal additional costs with respect to the starting ones (mostly replacement of some of the cameras, search party funding being sought by the regional centers). Our project is original in several ways. (i) It is inter-disciplinary, involving experts in meteoritics, asteroidal science as well as fireball observation and dynamics. It will thus create new synergies between prominent institutions and/or laboratories, namely between MNHN, Paris Observatory and Université Paris Sud in the Parisian region; and between CEREGE and LAM in the Provence region. Overall, scientists from over 25 laboratories will be involved, representing a mix of scientific disciplines and covering all the regions of France. (ii) It will generate a large body of data, feeding databases of interest to several disciplines (e.g. bird migration, variations of the luminosity of the brightest stars, observation of space debris, meteorology…). (iii) It will for the first time involve the general public (including schools) in the search for the meteorite falls, thus boosting the interest for science. (iv) Our observing technique will be completely new as it will integrate complementary tools (state of the art digital cameras in the visible range, radio and meteorological data) in a network denser than any built before (there are now about 50 all-sky cameras in Northern/Eastern Europe and there will be 100 in France only).

Knowledge about the deep interior of the Moon puts tight constraints on its formation and ultimately on the evolution of the Earth-Moon system. Measurements of the tidal response of the Moon resulting from the gravitational field of the Earth provide unique evidence on its inner working and can be obtained from orbiting spacecraft and Earth-based observations. Furthermore, the Moon dynamical monitoring is the most accurate ever made in the solar system thanks to the deployment of laser retro-reflectors (LRR) on its nearside surface leading to a centimeter accuracy over the past 40 years. Such accuracy requires a high accurate modeling of its orbit but also of its rotation, inducing a unique development in the inner structure for an object different from the Earth. This project aims at a synthesis of the a large amount of observations and modelings obtained from Earth-based Lunar Laser Ranging (LLR) and orbit-based laser altimetry (LA) to achieve an improved and consistent determination of the tidal deformation of the Moon by estimating its gravitational Love numbers and consequently constraining the present dissipation in the Earth-Moon system. Besides, planetary deformations are usually characterised with the help of a triplet of adimensional numbers, the Love numbers, giving the horizontal and vertical displacement of the surface (l and h) and the gravitational response to a potential of degre n for k. With the Love numbers, our modele can implement elastic and viscoelastic rheologies as well as effects induced by the asymmetric thickness of the Moon crust. This project is based on the association of the DLR team expert in Laser altimetry and the INPOP team, expert in LLR data analysis and planetary and lunar ephemerides construction. The following steps will be followed: i) improvements of the LA data analysis in considering improvements in the orbit determination of the spacecraft (in our case, LRO) and in using different versions for the libration modelings with INPOP and visco-elastic and asymmetric Love numbers in the data analysis procedure. By doing so, one will evaluate the sensitivity of the LA data analysis algorithm to inner structure assumptions. ii) In the INPOP libration modeles, one will add more complexity in the tides modeling in introducing high-order Love numbers, visco-elastic Love numbers and Love numbers obained in introducing asymmetry of the crustal thickness provided by our new modele of deformation including viscoelasticity and spatial heterogeneity in the crust. The expected results will be i) a better description of the tidal deformation of the Moon and the dissipation for the earth-moon system together with a better constraint on the visco-elastic rheology of the moon considering the lateral asymmetry of the crustal thickness detected by GRAIL ii) the set up of a method for constraining accurately inner structure of any planet in using high accurate LA observations. This final result will open a lot of possible applications to space missions such as Bepi-Colombo, JUICE or future mars missions.