AFP
China and France launch a satellite to better understand the Universe
It is a symbol of France-China space cooperation: the Asian giant launched a satellite on Saturday responsible for spotting “gamma bursts”, real luminous fossils which should provide more information on the history of the Universe.Elaborated by engineers from both countries, this mission called “Svom” (Space-based multi-band astronomical Variable Objects Monitor), a notable Sino-Western collaboration in space, aims to detect and locate these very distant cosmic phenomena, at the power monumental. The 930 kilo satellite contains four instruments (two Chinese, two French). It was launched into space around 3:00 p.m. Saturday (07:00 GMT) aboard a Chinese Longue March 2-C rocket from the space base of Xichang, in Sichuan province (southwest China), AFP journalists noted. But what is a gamma burst? To simplify, they generally occur after the explosion of massive stars (more than 20 times the mass of the sun) or the merger of compact stars. The most powerful explosions in the Universe, these bursts of radiation of colossal luminosity can release energy equivalent to more than a billion billions of suns.How, above all, are these gamma-ray bursts interesting?”Observing them is a bit like going back in time, because their light takes a long time to reach us on Earth, several billion years for the most distant”, explains to AFP Frédéric Daigne, astrophysicist at the Paris Institute of Astrophysics and one of the main French experts on gamma bursts. – “Very extreme” – While traveling through space, this light also passes through different gases and galaxies, carrying their imprints with it. Valuable information to better understand the history and evolution of the Universe.”We are also interested in gamma bursts for themselves, because they are very extreme cosmic explosions which allow us to better understand the death of certain stars”, notes Mr. Daigne. The most distant burst identified so far occurred just 630 million years after the Big Bang – or 5% of the current age of the Universe. “All this data also make it possible to test the laws of physics with phenomena that are impossible to reproduce in the laboratory on Earth”, underlines Frédéric Daigne. Once analyzed, this information can also be used to better understand the composition of space, the dynamics of gases and other galaxies. This project is the result of a partnership between the French (Cnes) and Chinese (CNSA) space agencies, in which several scientific and technical organizations from both countries also participate. Although not rare, these China-West space cooperations are not not so common at this level. Particularly since Washington banned NASA from any collaboration with Beijing in space in 2011. – Race against time – “The concerns of the United States in terms of technology transfer have contributed to slowing down collaborations between its allies and the Chinese But these still materialize occasionally,” Jonathan McDowell, astronomer at the Harvard-Smithsonian Center for Astrophysics in the United States, told AFP. China and France had already jointly launched the project in 2018. CFOSAT, an oceanography satellite used in particular for marine meteorology. European countries are also participating in the Chinese Chang’e lunar exploration program. So if it is not “unique” of its kind, the Svom project remains “important” in the context of Sino-Western space collaborations, underlines M . McDowell. The satellite, placed in Earth orbit at an altitude of 625 km, will send its precious data to observatories on Earth. Main difficulty: the extreme brevity of the gamma-ray bursts will engage scientists in a race against time to collect the information. .As soon as Svom detects a burst, it will send an alert to a team on call 24 hours a day. In less than five minutes, they will then have to trigger a network of telescopes on the ground which will align themselves precisely in the axis of the source of the burst, for more in-depth observations.ehl-juc/ia
