These fertile scientific and technological developments led to the decision of the French Government to join the SKA Observatory. After the announcement of this historical step in 2021 and the governmental signature of the accession agreement with the Observatory in 2022, the process of accession will be completed by the ratification of the agreement by the French Parliament.
Brief History of France's involvement with the SKAO
France has been amongst the founding partners in the first stages of SKA development, participating from 2005 to 2012 to the EC funded projects SKADS and PrepSKA. Even though for programmatic and financial reasons France could not join the SKA Organisation in 2011, the French scientific and technological implication in the project did not stop. French institutes have been involved in 5 of the 11 consortia designing the SKA telescope, including the Mid-Frequency Aperture Array, Wideband Single Pixel Feed, Low-Frequency Aperture Array, Dish and Science Data Processor consortia. France joined also international SKA pathfinder projects, such as the Low Frequency Array (LOFAR) and the Electronic Multi Beam Radio Astronomy ConcEpt (EMBRACE).
All this resulted in several major achievements, including the beginning of the construction of NenuFAR (New Extension in Nançay Upgrading LOFAR), a French LOFAR Super Station officially labelled as SKA pathfinder in 2014, and a good participation of French researchers to the SKA Science Book in 2015. The French CNRS roadmap for Astronomy published that year stressed the high priority of having France joining SKAO. In this framework, in 2016, CNRS with 4 other academic institutions (Observatoire de Paris, Observatoire de la Côte d'Azur, Université de Bordeaux and Université d'Orléans) decided to launch “SKA-France”, a structure in charge of the national coordination of scientific and technological activities in preparation of the SKA project.
In 2018, the national coordination became “Maison SKA-France” (MSF), a consortium involving public institutions (CNRS, Observatoire de Paris, Observatoire de la Côte d'Azur, Université de Bordeaux and Université d'Orléans, joined by Inria and CEA/DRF in November 2019) and private companies (Air Liquide, ATOS-Bull, Callisto, CNIM, FEDD, Kalray, Thalès). The creation of this partnership was motivated by the identification of the SKA project as a strong booster of scientific and technological innovation with significant potential returns, including low environmental impact computing and data centres, very high bandwidth digital electronics, integration and verification of complete systems, as well as challenges related to the production and management of renewable energy. Efforts from the French community were therefore put on these domains during the bridging phase between the end of the design consortia and the beginning of construction.
After the constitution of the MSF, it was also in 2018 that SKA entered as a project in the National Roadmap for Research Infrastructures and that the CNRS joined SKA Organisation. In 2021, the French government announced the decision of France's entry into the SKAO, which has integrated the 2021 National Roadmap for Research Infrastructure in the category of the Scientific Intergovernmental Organisations. Entry will be formal when the intergovernmental agreement will be ratified by the French Parliament, a process launched in mid-2021 following the announcement made by the President of the Republic in May during his official visit to South Africa. Pending the completion of the parliamentary process, the CNRS has signed in March 2022 a temporary collaboration agreement with SKAO, which will allow the first financial contribution to SKAO from France to be made in 2022, and the French government signed the accession agreement with the Observatory in April 2022.
Aware that the SKAO will provide a major quantum leap in observing capability over a wide range of radio frequencies, for the past 10 years the French astronomical community has ranked the SKA project as one of its highest priorities.
The French SKA White Book, published at the end of 2017, has gathered the contributions of 178 authors from about 40 institutions. It has shown that French interests cover the entirety of the accessible SKA scientific fields (in astrophysics, cosmology, and fundamental physics), with the French community aware that, for some topics, the SKA project will be the only one capable of making decisive progress; for others, it will provide complementary information indispensable for the best exploitation of other large modern observatories covering different frequency ranges of the electromagnetic spectrum.
Among similar publications (i.e. white papers edited by other countries and even the SKA Science Book), the French SKA White Book contains the richest chapter about synergies between the SKA and other projects, as well as a very original chapter about the physics of the interstellar medium.
Today, the French astronomical community is actively preparing for the future operation of the SKAO, through participation in all the Science Working Groups, with two SWGs co-chaired by French researchers (“Cradle of Life” and “Extragalactic Spectral Lines”).
A wider scientific community is also starting to be more widely involved in the preparation of the future SKA Regional Data Centres, seen in France as a world-scale demonstrator for reshaping the computing and data analysis ecosystems as part of an open and inclusive multi-stakeholder collaboration strategy, an essential component of the digital revolution.
Building the SKAO
France will lead the provision of the future SKAO computing centres with low environmental impact. This is fully in line with the French national strategy for high performance computing and data analysis, as well as the development of industrial solutions for renewable energies, which are major issues that show how fundamental research can be a driver for strategic innovation.
The New extension in Nançay upgrading LOFAR (NenuFAR) is a large array of some 2000 LWA-like crossed dipoles that observes in the lowest spectral range accessible from the ground, 10-87 MHz. It has been developed and built, and it is run at the Nançay Radio Observatory (ORN) with support from Observatoire de Paris, CNRS, Université d’Orléans, as well as a few international partners, especially the ASTRON NL institute.
The construction of NenuFAR is near completion (planned for 2023). It consists of ~100 analog-phased tiles of 19 antennas organised in a 400-m core and outliers up to 3 km, and a suite of receivers that allow one to do beamforming, imaging, and waveform capture, making it a flexible facility. Original technical developments include an efficient antenna preamplifier, the Virtual Control Room that allows full control of the telescope operations through a web interface, and a phased multi-tile trigger for waveform recording. NenuFAR will also be included as a very sensitive super-station in the LOFAR 2.0 array.
The telescope is exploited in “early science” (shared risk) standalone mode since mid-2019, and will start proposing open time by the end of 2022. Early science Key Programs cover a broad range of low-frequency science, from cosmic dawn to pulsar, fast radio bursts and exoplanets search, as well as solar system studies. Pipelines are being developed and a data centre based on cloud technologies is in preparation. The first papers have been published. NenuFAR helps building the French SKA users community and building experience at very low radio frequencies.
Developing New Technologies
The preparatory work towards the SKA and pathfinder telescopes has stimulated the following developments closely related to the need of new technologies:
- On-going implementation of a Computing Lab “ECLAT” (partners: CNRS, Inria, ATOS) whose first objective is to conduct co-design activities for the future SPCs. This joint laboratory will conduct its projects in partnership with international partners
- Between 2018 and 2020, Air Liquide, one of the MSF partners, has conducted a technological demonstration of autonomous SKA-MID antennas, for which liquid hydrogen would provide the cooling for the acquisition electronics and the electrical energy required by the antenna’s motors and electronics
- A team of the Nançay Radio Observatory has developed optimised ASICS for low energy consumption
Benefits for France
In 2019, the Agence Française de Développement (AFD) has financed a FASEP study (Private Sector Study and Support Fund) on all energy aspects of the future SKA observatory in South Africa. This study, conducted by CNIM/Bertin (one of Maison SKA-France partners), encourages the SKA Observatory to increase its ambitions in terms of non-carbon renewable energy, and incites French actors to be positioned on these challenges.
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