The James Webb telescope, a new look at the infinitely distant and ancient in the universe

Published on : 12/25/2021 – 09:50

He will be one of the first scientists in the world to gaze at the universe through the overpowered eyes of the new James Webb Space Telescope (JWT), due to launch on Saturday, December 25. Olivier Berné, astrophysicist at the Institute for Research in Astrophysics and Planetology, is part with his colleague Émilie Habart – of the Institute of Space Astrophysics – of one of the 13 first programs selected, out of about 200 submitted, to be able to take advantage of the first 460 hours of observation allocated by NASA.

“This is the culmination of a whole career. When I started working in 2004, we were already talking about the promises of the James Webb telescope”, recognizes this astrophysicist based in Toulouse, contacted by France 24. This device must take the falls under the famous Hubble Telescope after 31 years of loyal service in space.

To the Orion nebula and beyond

For him, “being one of the first to be able to have a new look at the universe at an unprecedented level of detail, it’s a bit like when Galileo received his new polished lenses to be able to observe the surface better. from the moon”.

This Frenchman will have the right to use the full power of the James Webb telescope for around 40 hours from the beginning of September 2022. Before that, the teams from the American NASA, theEuropean Space Agency (ESA) and of its Canadian counterpart ASC – who jointly designed the spacecraft – will take advantage of the first half of next year to calibrate and test this huge telescope, which is due to arrive at its destination 1.5 million km from Earth a month after takeoff.

Olivier Berné will ask to point the brand new telescope at the Orion nebula, which is 1,300 light years from Earth. “On a universe scale, it is kind of our direct neighbor. In fact, it is the region of star formation – with massive stars like those that existed in the youth of our system. solar – the closest to us “, specifies the French scientist.

The Orion Nebula is what is called a “star nursery”, that is, an area of ​​our universe that is still actively producing planets and stars. Through this observation of barely two days, Olivier Berné and his team hope “to better understand our origin because it is estimated that the solar system was formed in an environment similar to that of the Orion nebula”.

Other teams of scientists will be interested in other regions of the universe sometimes much further away from our Earth. One of the selected programs will seek to take the first truly detailed photos of exoplanets, another will attempt to unravel the mysteries of the atmospheres of these stars located outside our solar system. Finally, several scientists will observe clusters of galaxies more than 5 billion light-years from the solar system.

If astrophysicists are so eager to use the James Webb Telescope to explore the far reaches of the universe, it is because its main promise is to be able to see farther in time and space than Hubble.

The latter managed to take pictures of a galaxy located just over 13 billion light years from our solar system. The JWT should make it possible to go even further to capture the light emitted by stars born just a few hundred million years after the Big Bang.

The importance of infrared light

This is why astrophysicists expect so much from the new space telescope: it must open the largest window to date on the origins of the galaxy. “If we say that Hubble could see galaxies in their childhood, the James Webb telescope will allow them to observe them as babies”, summarizes NASA on its site dedicated to these powerful space observation tools.

A feat that comes from the ability of the JWT to observe infrared lights where Hubble could only perceive what is visible to the naked eye and in the ultraviolet spectrum. An evolution that changes everything, because “as the universe is expanding rapidly, distant objects move away faster and this distance generates what is called a ‘blush’ of the light they emit. In some cases, the light is shifted to the infrared and we therefore need a telescope capable of observing this light spectrum “, summarizes Olivier Berné.

But why did this French astrophysicist choose to focus the attention of this overpowering machine on the Orion nebula, a region which is only a few blocks from the Earth? The fact is that infrared is not only useful for looking very far away. “Another advantage lies in particular in the fact that the brightest signal from exoplanets comes from infrared radiation”, explains Olivier Berné. In other words, it is what could allow astrophysicists to have the clearest view of the planets outside our solar system.

This is all the more true as the “infrared light is very penetrating, which should make it possible to better observe the nebulae and to see through the clouds in order to get a more precise idea of ​​the atmospheric composition of the observed exoplanets and of the regions where these planets are formed, ”adds the French researcher.

In the quest of astrophysicists to find planets where life forms could develop, the study of atmospheres is often seen as one of the key elements.

Finally, even if Olivier Berné’s observations will not cover the infinitely far and the past, they could prove useful in understanding what happened shortly after the Big Bang. The Orion nebula has in fact already been well observed with other telescopes and using the JWT will make it possible to relate certain infrared signals with already known physical characteristics. “We hope to be able to create a toolbox, a kind of benchmark for other observations,” concludes Olivier Berné.

But all that is for much later. For now, the French astrophysicist is impatiently waiting to be able to take a look at the first pictures of the Orion nebula. Photos that will be very expensive because taken with a telescope whose construction will have cost nearly 11 billion dollars.