The aim of astronomy is to observe, study and understand celestial bodies and the Universe. It is one of the oldest sciences and addresses fundamental questions about our origins. These questions fascinate and hold immense appeal for the general public and young people in particular, placing astronomy at the centre of major societal issues linked to the great democratic and ecological challenges of our time.

Understanding our origins means understanding how multiple and complex physical and chemical phenomena operate, coupled on many orders of magnitude in terms of spatial and temporal scales.

• Origin of the Universe and its contents
  The study of the Universe as a physical object has made significant progress over the last twenty years, thanks in particular to the contributions of laboratories in the Île-de-France region. The use of increasingly precise techniques has enabled us to build a coherent model of the Universe, its contents and the first moments of its existence.
  This model assumes the existence of two ingredients whose nature remains unknown: dark energy and dark matter, which combined account for 95% of the content of the Universe. A third key element of this model is inflation, which describes how the Universe expanded extremely rapidly in its early days, but whose exact mechanism has not yet been identified. Atoms (ordinary matter) make up only 5% of the content of the Universe. During primordial nucleosynthesis, only lightweight elements were produced, resulting from fusion processes at very high temperatures in the then very dense Universe. It was not until a hundred million years later that a new process, governed by gravitation, brought the matter together in stars, at the heart of which heavier elements were formed. This stellar nucleosynthesis produced most of the atoms that form us. A detailed understanding of the nucleosynthesis processes that trace the origin of atomic elements has yet to be established.
  Faced with these fundamental questions, a number of international observational projects involving our laboratories will begin their observations, such as the Euclid space mission (launched by ESA in early 2023), the LiteBird mission (to be launched in 2027) and, in the longer term (launch planned for 2032), the Lisa mission. We should also mention the involvement of several teams from the Île-de-France region in the scientific operation of the Vera Rubin Observatory (LSST), which will come on stream in 2024. These instruments use cutting-edge detection techniques and innovative data processing methods based on numerical simulations.

Euclid - tests before launch into space. Credits: ESA-Manuel Pedoussaut.

• Origin of structures in the Universe
  While the origin of the great structures of matter in the Universe is now well understood, understanding how they evolve over time remains a significant challenge for modern astrophysics.
  The new JWST infrared space telescope launched at the end of 2021 to study small scales (stars, galaxies, black holes), and the Euclid space mission to observe large structures and their assembly will play a key role in answering these questions, and several of our teams are heavily involved in their scientific exploitation.
  These missions will be supported from the ground by a number of instruments which will also start gathering data on the largest telescopes: MOONS at the VLT and WEAVE on the Canary Islands will observe thousands of galaxies at the same time, providing samples of millions of objects to be analysed. In the radio field, the precursors of the future SKA radio astronomy network, such as LOFAR and NenuFAR, will produce equally important samples. The GRAVITY+ interferometer will enable the detailed study the relationship between the central black holes of galaxies, their active nuclei and the winds/jets that develop within them. Most of these projects were supported by the Île de France region via DIM ACAV+, which made a major contribution to their development and construction in collaboration with local manufacturers.
  Our laboratories are also heavily involved in preparing the next generation of radio instruments (SKA; 2026) and visible instruments (MICADO and MOSAIC projects for the ELT; 2027), which will be essential for understanding how galaxies have ’reionised’ the Universe, transforming its large-scale gas content from a neutral state to an ionised state. Last but not least, the Gaia satellite, whose measurements will revolutionise our understanding of the structure and functioning of our galaxy.
  All these instruments will deliver massive quantities of increasingly precise data, the processing and archiving of which will require the development of innovative solutions. The scientific interpretation of the data, published in open archives as soon as it is produced, is a major challenge in the context of very strong international competition, for example in the case of the Gaia catalogues produced by our teams, and also requires increasingly massive and sophisticated digital simulations. Researchers in the Île-de-France region are highly regarded in this field and form an internationally recognised centre of expertise.

Map of our galaxy, the Milky Way, and its immediate surroundings, produced by the Gaia satellite. Credits ESA/Gaia/DPAC.

• Origin of gravitational waves and astrophysical cataclysms
  Astrophysical cataclysms such as gamma-ray bursts, supernovae and eruptions of active galactic nuclei involve compact objects such as black holes or neutron stars. Our understanding of them depends to a large extent on our ability to study all the radiation emitted in detail: photons at all wavelengths, gravitational waves, but also neutrinos and charged cosmic rays. These so-called multi-messenger observations may help to reveal new physics, in particular the nature of dark matter.
  The last few years have seen the first detections of gravitational waves, opening up a new window on the most violent astrophysical phenomena. The next few years promise to be rich in discoveries. In the X-ray and gamma-ray fields, our teams are preparing the Athena mission, to be launched in 2031. The Franco-Chinese SVOM satellite (launched at the end of 2022) will detect many gamma-ray bursts, while maximising the potential for multi-messenger detection. At even higher energies (TeV), the CTA observatory is gradually coming on stream.
  As far as gravitational waves are concerned, LIGO-Virgo-KAGRA resumed observations in mid-2022 with improved sensitivity. At the same time, the development of the eLISA space mission continues to progress, as does the study of the Einstein Telescope. For neutrinos, the large KM3NeT detector is currently being deployed. Preparations for the future GRAND radio network are also in full swing, with the installation of a prototype comprising 300 antennas. Finally, the Pierre Auger Observatory is currently undergoing major redevelopment in order to understand the composition of ultra-energetic cosmic rays.
  The coming years will see a massive increase in the number of transient events detected, and the challenge will be to structure our communities in order to coordinate all the multi-messenger and multi-wavelength observations required. The teams in the Île-de-France region have the expertise to rise to this challenge successfully and play a leading role in this new era for astronomy.

KM3NeT detector - KM3NeT collaboration credits.

• Origin of stellar objects and complex matter
  The interstellar medium is a complex, open system that constantly exchanges matter and energy with stars and the extragalactic medium. Dense, compact and cold cores lead not only to the formation of stars, but also of protoplanetary disks and planetary systems.
  During all these stages, new molecules are formed, dust grains evolve and grow to form proto-planetesimals. Molecules, dust grains and complex ice mantles evolve under the effect of multiple processes: radiolysis, UV and X-ray photochemistry, aggregation, chemistry coupled to gas dynamics, heterogeneous chemistry at the surface of grains, thermal effects, etc. Laboratory simulations reveal an impressive molecular richness and raise questions about the extension of the frontier of chemical complexity achievable in the interstellar medium.
  Assessing the role of each of these processes is crucial to understanding the formation and evolution of the interstellar structures that lead to the formation of stars and planets. To achieve this, it is necessary to support, develop and bring together dedicated laboratory experiments, elaborate numerical models, large-scale numerical simulations and the use of major space or ground-based observatories to establish observational diagnoses.
  In particular, the Île-de-France laboratories have developed expertise in laboratory astrophysics that enjoys international recognitions in the fields of planetology, spectroscopy, molecular physical chemistry and dense plasma physics. The multidisciplinary networking of this expertise within DIM ORIGINES positions the region at the forefront of this rapidly expanding international field.

Birth of a star James Webb Space Telescope -Rho Ophiuchi cloud.
Credits: NASA, ESA, CSA, STScI, Klaus Pontoppidan (STScI).

• Origin and diversity of planetary systems
  The solar system is home to planets, satellites and small bodies of great physical and chemical diversity. The Île-de-France community plays a leading role in major missions to explore the solar system, our planet’s environment in space and its interaction with the Sun (Solar Orbiter, Parker Solar Probe) and in the study of the origin of the solar system through the analysis of extraterrestrial samples (meteorites and samples taken from asteroids, the Moon, Phobos, Venus or Mars).
  In planetology, the Bepi-Colombo (start of operations in 2026) and JUICE (launch in 2022) missions will explore Mercury as well as Jupiter and its series of icy satellites. The current and future missions to Mars, Insight (launched in 2018) and Mars 2020 (launched in 2020) will determine its internal structure and characterize its subsurface in order to understand its geological evolution. MMX (launched in 2024) will explore Martian satellites to understand their origins.
  These missions will seek to understand the evolution of the Martian atmosphere, track down chemical traces of possible past life and prepare for transporting Martian samples to Earth by 2030. This research is also based on theoretical and numerical developments in which we are a driving force: the dynamics and stability of the solar system, the origin and evolution of small bodies, tidal mechanisms in gravitational interactions, particularly in the evolution of the Earth-Moon system, which has played a key role in the Earth’s climatic stability, and the modelling of planetary atmospheres and their evolution.
  Observations of exoplanets reveal an even greater diversity, with gas giants located very close to their stars, atmospheric temperatures of several thousand Kelvin, and planets with masses intermediate to those of the Earth and Neptune that have no equivalent in the Solar System. The challenge is to discover a planet with physical and chemical conditions similar to those on Earth.
  The Île-de-France community is heavily involved in future space missions to detect and characterize exoplanets (JWST; Plato, launch in 2026; Ariel, launch in 2029). It has established itself as a leader in the high-contrast imaging of exoplanets, in particular with the SPHERE and GRAVITY instruments for the VLT and their successors currently under study, SPHERE+ and GRAVITY+, as well as in the preparation of instrumentation for the ELT (MICADO, METIS, PCS). These new instruments will have to incorporate innovative techniques to achieve unprecedented contrast and resolution, thanks in particular to ever more powerful adaptive optics systems whose deformable mirrors, detectors and real-time computers are developed in collaboration with industry, often locally.

Artist’s view of the Extremely Large Telescope - Credits ESO.

• Origin of life
  Over the last twenty years, the discovery of nearly 5,000 extrasolar planets has considerably changed our approach to this question, by revealing the existence of planetary systems around most nearby stars. The challenge will be to identify, from among the diversity of these worlds, those where the physico-chemical conditions may support the development of life forms.
  Planetary habitability is the result of global processes coupling internal dynamics with the planet’s surface and atmosphere, such as volcanism, plate tectonics and the presence of a magnetic field. These processes are controlled by the chemical properties of the initial constituents. An essential condition for the habitability of a planet is its position in relation to its star and the evolution of its atmosphere, conditioned by the insolation at its surface, which in turn depends on the orbital and rotational evolution of the planet.
  The coming years will mark an important turning point, with the first measurements of the chemical composition of the atmospheres of Earth-like planets located in the habitable zone of their host star (JWST and ELT). These observations will pave the way for the search for signs of life through the possible presence of molecules. Laboratory experiments play a crucial role in the development of space instruments, observational strategy and the exploitation and interpretation of data. DIM ORIGINES can play a decisive role by bringing together the scientific (astronomers, physicists, chemists, biologists, geologists) and methodological expertise needed for a global approach.
  Studying extraterrestrial organic matter in primitive objects (meteorites, micrometeorites, asteroidal or cometary surfaces) is a key challenge if we are to understand the mechanisms of formation and evolution in the nascent solar system, and its possible contribution to the emergence of life on Earth. The coming years will be exceptional, with the return to Earth of carbonaceous asteroid samples by the Hayabusa-2 and OSIRIX-REx space missions (scheduled for 2023) and, in the longer term, surface samples from a Martian moon (Phobos) by the MMX mission (launch in 2024).
  Analyses of these samples and their comparison with data from recent space missions (Rosetta, Stardust) and data obtained from primitive objects available in museum collections will be put into perspective with studies of the oldest forms of life on Earth. Our laboratories have world-renowned expertise in this field. The project to locate the future Centre National de Conservation de la matière Extraterrestre (National Centre for the Conservation of Extraterrestrial Matter) at the MNHN will strengthen collaboration between teams in the Île-de-France region, who will benefit from an infrastructure with international visibility.

Mission MMX- Artist’s view- Credits: JAXA/NASA.