James Webb telescope makes discoveries in the outer rim of our solar system

The James Webb Space Telescope (JWST) was designed to look far into the future, to collect the faint light coming from the depths of the Universe and to probe the recesses of space-time. Yet it is well known that less is more – and so, it sometimes happens that the JWST stops aiming for the distant and focuses on our own backyard, the Solar System.

Of course, parked on the outskirts of the Earth, 1.5 million kilometers away, the space telescope can’t achieve the same degree of precision as a probe orbiting a planet. Of course, with its body perpetually turned away from the Sun (and the Earth) to keep its instruments as cold as possible, it’s impossible for it to observe our own star, the comets that brush against – or plunge into – it, Mercury, Venus and our own planet.

Once these restrictions have been taken into account – and noting that Mars is well covered by orbiters and rovers – it’s clear that the JWST must concentrate on the “outer Solar System,” in other words, everything beyond the Martian orbit. Therefore, among the first images gathered by the spacecraft were shots of Uranus, Neptune and their respective rings. These two planets, the furthest away from us, had not been so well observed since the Voyager-2 probe flew over them in the second half of the 1980s.

Jupiter’s icy moon

Several of the latest results obtained thanks to the James Webb telescope concern the Jovian and Saturnian planets and moons. In a study published on October 19 in Nature Astronomyan international team announced the detection of a previously unseen high-altitude current above the equator in Jupiter’s atmosphere.

A few weeks earlier, in September, two independent teams revealed the presence of carbon dioxide on the surface of Jupiter’s icy moon Europa, thanks to observations that took just a few minutes of the space telescope’s precious time. The researchers believe that the CO₂ in question emanates from the ocean beneath the thick layer of ice that lines this satellite. Now, if this ocean were to contain carbon – the basic building block of organic molecules – this would reinforce researchers’ interest in Europa, towards which NASA will be sending a probe in autumn 2024. Europa Clipper will attempt to determine whether this moon is or was suitable for the appearance of life.

On Saturn, it was the satellite Enceladus that attracted the most attention, with the May announcement of the detection of an immense plume of water vapor – some 10,000 kilometers long – emanating from its south pole. Like Europa, Enceladus conceals a deep ocean beneath its surface ice, and is agitated by cryovolcanism. These geysers propel a mixture of ice particles, water vapor and various molecules into space. Every second, 300 kilograms of matter are sprayed out in this way, according to JWST data analysis, and as this moon only takes around 30 hours to circle Saturn, it creates a kind of steamy donut around the giant planet. This makes Enceladus the main water source in the Saturnian system.