What is James Webb and why it could change everything we know about the Universe

The James Webb Space Telescope is finally ready for the most ambitious scientific mission ever: it will study the origin of the Universe and dark matter

The James Webb mission is perhaps the most eagerly awaited scientific space mission ever. Technicians and scientists from 15 countries have been working on the most powerful space telescope ever built since 1996, for a project initially scheduled for launch in 2007.

Today, the James Webb Space Telescope is on the ground in French Guiana, positioned atop the Ariane 5 rocket that is tasked with sending it into orbit around the Sun at a distance of 1.5 million kilometers from Earth. With just a few days to go before the long-awaited departure of the historic mission, now postponed countless times, let's see why James Webb could forever change everything we know about the Universe.

An unprecedented look at the Universe

It's not every day that a six-tonne payload is sent into space in one go, costing nearly $10 billion, compared to the $500 million planned in the 1990s.

The James Webb Space Telescope will be sent to its observing location, a Lagrange point, a particularly stable position in the solar orbit. There it will take six months only to prepare its incredible instruments, including a 6.5-metre primary mirror, which will slowly deploy into the cosmic void to be ready for action in mid-2022.

With its infrared instrumentation, James Webb will be able to investigate the atmospheres of potentially habitable planets far from Earth, and reveal information that has so far been hidden from us by the impermeability of the Universe.The TSJW will study the structure of the Universe by analysing the brightness of known stars, and its investigation could even shed light on perhaps the most hidden mystery of our Universe: the nature and density of dark matter and dark energy.

The James Webb's instrumentation can detect cosmic objects at distances never before reached, allowing us to investigate the origin of the first stars to form after the Big Bang: a glimpse into the past of the early Universe. If Hubble's eye was able to capture images of galaxies with more than 10 billion years of life behind them, James Webb could finally illuminate the events of the first 100 million years of our Universe's life.

This is no ordinary space telescope: according to Roberto Maiolino, of Cambridge University, "in ten years we will make discoveries for 400 years," starting with the investigation of "how the first key elements of the Universe were formed" following the cooling of hydrogen that began the dance of celestial bodies.

A complicated history

James Webb has had until now, it is true, a rather complicated history: endless costs, delays, postponements, even - more recently - several controversies about the name chosen for the instrument. James Webb was in fact the administrator of NASA at the time of the first missions that brought astronauts into space: in short a politician, not a scientist.

The interminable years of development of the James Webb Telescope have allowed to incorporate within the mission even more ambitious projects, such as the study of those "alien" planets - the exoplanets - that in the nineties, before Hubble, we did not even believe existed in such quantity.

The TSJW will in fact be engaged in the analysis of the atmosphere of some exoplanets: to understand the importance of this evolution, just think that astronomers today study the more than 4 thousand exoplanets detected beyond the Solar System based on data provided only by the visible light of these planetary systems. The infrared of James Webb could instead reveal the existence of an "alien" atmosphere capable of hosting life.

In short, the wait is great: we are about to launch at more than a million kilometers from Earth, beyond the Sun, an instrument that bears the signs and results of 25 years of evolution and scientific research, born when we still did not know of the existence of distant planets perhaps suitable to host life and ready to leave for its historic mission only today.

As ESA's Torsten Böker says, "we can expect to be surprised" by what James Webb will be sending us starting next year; "we will see things we never even dreamed we could see," Böker continues, "something priceless."