After a first photograph published the day before, NASA yesterday revealed all of the first images of the most powerful space telescope ever designed, James Webb, images marking the start of its scientific operations, expected for years by astronomers around the world. . On the program of a live one hour during which the images were revealed one by one: two nebulae illustrating the life cycle of stars, an exoplanet and a compact group of galaxies. “Each image is a new discovery,” NASA boss Bill Nelson said in the opening. “Each will give humanity a view of the Universe that we have never seen before,” he added. On Monday, a first image taken by the telescope, illustrating the distant times of the cosmos, was unveiled in the presence of US President Joe Biden, who hailed a “historic” moment. The shot, which is teeming with detail, shows galaxies formed shortly after the Big Bang, more than 13 billion years ago.
One of the main missions of James Webb, a jewel of engineering worth 10 billion dollars and the most powerful space telescope ever designed, is indeed the exploration of the very young Universe. This first demonstration was intended to give an overview of its capabilities in this area. But it was only one of the five targets announced by NASA for this real surprise bag, which officially marks the beginning of the scientific observations of the telescope, and whose contents had until now been carefully kept secret in order to make build up the suspense. Among them: the images of two nebulae, very photogenic and gigantic clouds of gas and dust. The Carina Nebula, located about 7,600 light-years from our planet, illustrates star formation. It is home to many masses, several times the size of our Sun. The Southern Ring Nebula is a so-called planetary nebula (although it has nothing to do with planets): it is a huge cloud of gas surrounding a dying star. Another target: Stephan’s Quintet, a group of galaxies interacting with each other.
Scientific Adventure
The last cosmic object whose observation was revealed yesterday Tuesday is an exoplanet, that is to say a planet in orbit around a star other than our Sun, one of the main lines of research of James Webb. It was not actually photographed, but analyzed by spectroscopy, a technique used to determine the chemical composition of a distant object. In this case WASP-96 b, a giant planet composed mainly of gas. By combining the data obtained previously thanks to other telescopes and those by James Webb, “we will probably be able to detect water vapor” in its atmosphere, estimated José A. Caballero, astronomer at the Centro de Astrobiologia in Spain and specialist in exoplanets. These data “will be interesting for me to see the capabilities of the telescope and the instruments”, he added, although he considers this first exoplanet a bit “boring” and looks forward to smaller and less hot ones. observed.
James Webb had been launched into space about six months ago, on Christmas Day, from French Guiana by an Ariane 5 rocket. The result of a huge international collaboration and in the works since the 1990s, he is stationed at 1.5 million kilometers from Earth. The publication of these first images marks the beginning of an immense scientific adventure, which should extend over many years and transform our understanding of the Universe. Researchers around the world have reserved observation time with James Webb, whose program for its first year of operation has already been carefully determined by a committee of specialists and made public. The telescope has enough fuel to operate for twenty years. Some 20,000 people worked on this project around the world, making a huge international collaboration.
An “eye on the sky”
At the same time, the Extremely Large Telescope (ELT), the most powerful optical instrument ever built which will considerably increase the observation capacity of astronomers, is slowly coming out of the ground in northern Chile, one of the best places to turn to the stars. This new “eye on the sky”, which will be added from 2027 to the powerful observation instruments already in service in the Atacama Desert, will make it possible to multiply by 5,000 the current observation capacity and to point the a look at hitherto unknown places to answer questions still open about the origins of the Universe.
“There are certain scientific questions that we would like to answer, and these questions lead to the need for technology that helps us answer them,” explains Chilean astronomer Luis Chavarria, of the European Southern Observatory (ESO), which funds the study. construction of the ELT. “Astronomy always works at the edge of technology, at the edge of detection, at the edge of all that these wonderful instruments can provide,” he says. Current observing instruments, such as the Very Large Telescope (VLT) – the most powerful instrument currently in operation – and ALMA, the largest radio telescope in the world, both located in northern Chile, are capable to answer the questions that scientists were asking themselves three decades ago.
But the limits of knowledge have been pushed back, forcing the construction of even more efficient instruments, such as the ELT, which will be installed at an altitude of more than 3,000 m on the hill of Armazones, about twenty kilometers from the VLT, owned by ESO in the middle of the desert. The ELT, whose construction began in 2017, will consist of a primary mirror 39 m in diameter, made up of 798 small hexagonal mirrors. It will be housed in a huge hemispherical dome 85m in diameter which will culminate 74m above the ground. Two rounded doors will open laterally to allow observations at night.
The current optical telescopes, with a diameter of 8 to 10 m, have above all enabled scientists to discover exoplanets, these planets in orbit around other stars where the search for traces of life is concentrated. But to deepen their knowledge, more precise, and therefore larger, observation instruments are needed, capable of collecting a greater quantity of light. With its diameter of 39 m, the ELT “will collect 15 times more light than optical telescopes in operation today and will provide images 15 times sharper than those of the Hubble Space Telescope”, according to ESO. “It’s a project for the future that will allow us to reach other distances in the Universe,” says Susy Solis, geologist and technical assistant for the construction of the ELT.
The climatic characteristics of the Atacama Desert and its arid weather, which allow observations in a perfectly clear sky a very high proportion (90%) of nights of the year, make it a particularly favorable place for astronomical observations.
One of the ultimate goals of the ELT will be, according to the ESO, to have images “of rocky exoplanets to characterize their atmospheres and directly measure the acceleration of the expansion of the Universe”.
Source: AFP
After a first photograph published the day before, NASA yesterday revealed all of the first images of the most powerful space telescope ever designed, James Webb, images marking the start of its scientific operations, expected for years by astronomers around the world. . On the program for a one-hour live broadcast during which the images were…