Next-generation James Webb telescope will reveal the mysteries of galaxy formation
After three decades in the making, the world’s largest and most advanced space telescope will delve deeper into the cosmos than its predecessors and shed light on, among other things, the mysteries of galaxy formation in the early Universe, as well as the birth of stars in our own Milky. Galaxy shape.
The James Webb Space Telescope, named after former NASA Administrator James Webb, will launch on December 22 from the European spaceport in French Guiana, aboard an Ariane 5 rocket. Looking back billions of years in time, it promises to fill key gaps in our understanding of the history of our Universe.
“JWST will answer many questions from the edge of the universe. It will also allow us to study the atmospheres of planets in other solar systems in much greater detail than would otherwise be possible, ”Mark McCaughrean of the European Space Agency and member of the JWST Scientific Working Group told FRANCE 24.
Conceived more than thirty years ago and at a cost of $ 9.7 billion, the telescope is an international collaboration between the National Aeronautics and Space Administration (NASA), the European Space Agency (ESA) and the Canadian Space Agency ( CSA). Europe has provided 1.5 of the four science instruments in addition to the Ariane 5 launcher.
One of the most striking features of JWST is its primary mirror, which is 6.5 meters in diameter and consists of 18 hexagonal segments. Once in orbit, these 18 moving segments will need to be aligned with extremely high precision (on the order of nanometers) to form the main mirror.
Equipped with a giant sunscreen and four instruments including cameras and spectrographs, JWST will orbit the Sun at a distance of 1.5 million kilometers from Earth and make observations primarily at infrared wavelengths.
“The first galaxies formed so far back in time and so close to the Big Bang that when the light reaches us, it is very weak and has been redshifted by the expansion of the Universe into the infrared. So you need a telescope that is powerful and works in infrared; It must also be cool to avoid shining in the infrared. JWST is all of those things, ”says McCaughrean.
Exoplanets images
Among other important objects that the JWST will study are exoplanets, that is, planets that orbit distant stars beyond our solar system. While previous missions have detected the presence of hundreds of these planets, JWST will go a step further by directly imaging some of them, as well as spectroscopying the atmospheres around them.
One of the key instruments that will enable these measurements is called MIRI (for Mid-InfraRed Instrument) which has been developed through a partnership between ESA, a consortium of European institutes, and NASA. MIRI consists of a camera, stellar coronagraphs, and two spectrometers. Coronagraphs, developed by the LESIA laboratory at the Observatoire de Paris, drastically reduce the flow of bright objects compared to nearby faint ones. This will allow us to observe exoplanets alongside bright stars, as well as the active centers of galaxies.
In addition to revealing the mystery of how galaxies formed in the early Universe and imaging exoplanets, JWST will also look at our own galaxy, the Milky Way, enhancing our understanding of how young stars are born and how planets around them form. stars.
According to McCaughrean, JWST will also be an important component of multi-wavelength astronomy in which instruments operating at different wavelengths are trained in the same part of the sky for a comprehensive analysis of a phenomenon.
“For example, the Hubble Space Telescope has already made extensive observations in the optical and ultraviolet of distant galaxies that JWST will track in the infrared,” says McCaughrean.
JWST’s impressive features are the result of several innovative technologies. “The main mirror of the Hubble Space Telescope is 2.4 meters wide. JWST’s mirror is three times the size, but the entire observatory only weighs half that of Hubble. One of the main reasons JWST is so much lighter is because its mirrors are made of beryllium and not glass, ”he adds.
The other crucial element of the observatory is its giant parasol that will unfold only after the observatory is launched into space. “The technology related to this five-layer parasol, the size of a tennis court, had to be invented since it did not exist before.”
Made from a specially coated lightweight material called Kapton, the diamond-shaped lens hood will help cool the telescope to a staggering -223 ° C. “It will have about 300 kilowatts of sunlight reaching one side of the hood, while the other side where the telescope will be placed, it will have a few tens of milliwatts, “says McCaughrean.
