James-Webb telescope: how France participated in making the next space revolution

On December 25, an Ariane 5 rocket will send the James-Webb space telescope into orbit to take over from the famous Hubble. Initiated at the end of the 1980s, this technological gem will upset our vision of the universe.

The space adventure is part of the long term. When the first milestones of the James Webb Space Telescope (JWST) were laid in 1989, its predecessor the Hubble telescope had not even gone into space yet. But the future is being prepared long in advance and it is finally 32 years later that this incredible tool of more than 6 tonnes, the size of a tennis court, is about to begin the mission.

Unless there is a last minute change, the James-Webb telescope must leave Kourou, in French Guiana, on board an Ariane 5 rocket on December 25. It is one of those milestones that mark space history like the Curiosity rover on Mars or the Philae robot on comet Rosetta. A technical feat, the result of international collaboration, which will open up a new aspect of space exploration.

To fully understand the impact of this highly anticipated telescope, just look at what its big brother Hubble, launched into space in 1990, was able to bring. Most of the incredible photos of galaxies, supernovas or planets come from this telescope, although they are subsequently refined and colorized for better rendering.

Unlike telescopes on Earth, space telescopes installed in Earth orbit are not hindered by the atmosphere to obtain better shots, capturing both light visible to humans but also invisible spectra (infrared, gamma rays, etc.) . It is to Hubble that we owe the proof of the existence of black holes, the refinement of the age of the universe or the idea of ​​the immense number of galaxies present in the universe.

Nearly $10 billion

James-Webb, named after the former boss of NASA during the first step on the Moon, promises to take a new step. Its main mirror, a tool for capturing the famous light spectra, measures 6.5 meters in diameter (against 2.4 meters for Hubble). More powerful and located 1.5 million km from Earth (against 600 km for Hubble), it promises to detect the tiny lights of the first stars to appear at the edge of our universe. It should also tell us more about how galaxies were formed. Finally, since each chemical component has a spectral signature, it will be able to determine if an exoplanet has the conditions necessary for life (presence of methane, ozone, water, etc.) or even if it has traces of life.

The stakes are high, the budget too: 9.7 billion dollars, mainly disbursed by NASA (7.9 billion dollars). But Europe is not disconnected from the project since the European Space Agency (ESA) has provided one of the four instruments, the MIRI (Mid-InfraRed Instrument) which will make it possible to observe far infrared light. France was responsible in particular for one of the two parts of this instrument, the MIRIM imager (equivalent to a camera), developed between 2004 and 2009 by Cnes, CEA and several French laboratories.

Another tricolor actor to take part in the adventure: Arianespace, responsible for sending the telescope into its distant orbit, 1.5 million km away. If the Ariane 5 rocket is more used to sending satellites near our planet, it was already responsible for launching in 2009 Herschel and Planck, two scientific satellites at the Lagrange point L2, the same as the orbit point scheduled for James-Webb.

But this launch will remain that of the "decade" for the industrialist who has been working for several years on the adaptation of his launcher for this mission, in particular to ensure the deployment of the huge telescope. The latter will take about a month to get into orbit and another 5 months more to start its work.

This trip will also be one of the last for Ariane 5, which will make way for the new Ariane 6 launcher in 2022. One last mission to end in style.