ESA Space Science

The European Space Agency (ESA) reacted promptly to the discovery of comet 3I/ATLAS on 1 July 2025. Soon after they were alerted to its existence by automated detection systems, ESA astronomers began using ground-based telescopes in Hawaii, Chile, and Australia to monitor its progress.

Since then, the comet has been observed by space telescopes close to Earth, including the NASA/ESA Hubble Space Telescope, the NASA/ESA/CSA James Webb Space Telescope, XMM-Newton and XRISM. 

In October and November 2025, ESA turned interplanetary voyagers Mars Express, ExoMars Trace Gas Orbiter and the Jupiter Icy Moons Explorer (Juice) in the direction of the comet to make further observations from excellent vantage points. The data from Juice has recently arrived on Earth and scientists are busy analysing them to see what they reveal.

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The European Space Agency’s mission to discover Earth-like exoplanets, Plato, is now sealed in the Large Space Simulator (LSS) chamber at ESA’s Test Centre for a series of vital tests under space‑like conditions.

Engineers placed Plato in the LSS on 18 February, and since the beginning of March the spacecraft has been experiencing the extreme temperatures and vacuum of space. This photo captures the satellite standing in the centre of the simulator, moments before the chamber was bolted closed.

The picture was taken from the top opening of the LSS and gives us a direct view of Plato’s 26 ultrasensitive cameras. These are the special eyes that the mission will use to monitor more than 150 000 bright stars at the same time, hunting for terrestrial planets orbiting Sun-like stars.

The mission is expected to be ready for launch by the end of the year. Liftoff on an Ariane 6 is planned by Arianespace for January 2027.

But before launching a spacecraft, it is crucial to operate it and check all its functionalities in a space-like environment. The LSS offers just that.

A cylindrical container standing 15 m high and 10 m wide, the LSS is Europe's largest cryovacuum chamber. Equipped with a high-performance pump, the enclosure achieves a pressure a billion times lower than the sea-level atmospheric pressure, while liquid nitrogen circulating around its casing reproduces the extreme low temperatures of space.

Exposed to a grid of powerful heating elements (so-called ‘calrods’) that simulate the heat of the Sun, the backside of the spacecraft – with solar panels and sunshield – reaches a toasty 160 °C. At the same time, thanks to the sunshield and excellent insulation, the cameras and the optical bench facing the dark, cold part of the chamber are kept very cool at around –80 °C, as if facing deep space. 
Plato will reemerge from the space simulator at the end of March.

[Image description: Photo taken looking down into a black‑walled cylinder, at the bottom of which sits a large satellite with black panels and golden surfaces. On top of the spacecraft, we see the blue, shiny lenses of 26 large cameras. The cameras are mounted on a five‑stepped platform and arranged in four rows of six cameras, plus a top row with two cameras.]

The Smile spacecraft has arrived at Europe’s Spaceport in French Guiana. During the coming weeks, the spacecraft will go through final preparations for its launch on a Vega-C rocket between 8 April and 7 May.

What happens when a solar superstorm hits Mars? Thanks to the European Space Agency’s Mars orbiters, we now know: glitching spacecraft and a supercharged upper atmosphere.

Craters, craters, and yet more craters: this snapshot from ESA’s Mars Express is packed full of them, each as fascinating as the last.

For this month’s ESA/Hubble Picture of the Month, NASA/ESA's Hubble Space Telescope is joined by ESA’s Euclid to create a new view of the most visually intricate remnants of a dying star: the Cat’s Eye Nebula, also known as NGC 6543.

Just over a year since Smile arrived in the Netherlands in two parts, the now-complete and thoroughly-tested spacecraft has left for good. With a launch window set for 8 April – 7 May on a Vega-C rocket, the joint European-Chinese mission is almost ready to embark upon its unique space mission.

The journey of Juice

Video series covering Juice's journey to Jupiter

Plato, the European Space Agency’s mission to discover Earth-like exoplanets, successfully passed a first round of tests designed to ensure that the spacecraft is fit for launch. As this video shows, the tests consist of vigorously shaking the spacecraft to mimic the powerful jolts and vibrations that Plato will experience during launch.

These so-called ‘vibration tests’, are arranged in three parts. In this clip, we see the phase when the spacecraft, mounted on a ‘quad’ shaker, is jolted up and down (Z axis). In the other two stages, on top a ‘lateral’ shaker, the spacecraft is jiggled back and forth sideways in two perpendicular directions (X and Y axes).

Each test run lasts one minute, during which the frequency of the oscillations is gradually increased from 5 to 100 oscillations per second (hertz). At the higher frequencies we can no longer perceive the movement, but we hear the spacecraft’s internal rumbling caused by the fast shaking. The sound comes in waves, becoming louder when the shaker hits resonance frequencies and makes the spacecraft vibrate more intensely.

The first couple of minutes of a satellite's spaceflight are the toughest, as it sustains the extreme vibration of lift-off. By subjecting the spacecraft with these dramatic stresses in advance of the real launch, engineers ensure that no piece of space hardware will be damaged during launch.

Plato is currently undertaking its tough exams to graduate for launch. After vibration tests, the spacecraft was placed inside ESA’s acoustic test chamber and blasted by deafening sound similar to what it will experience during lift-off. Also this test went as expected.

Next, engineers will move the spacecraft to the Large Space Simulator â€“ Europe’s largest vacuum chamber – to verify that it can withstand the extreme temperatures and emptiness of space.

The mission is expected to be ready for launch by the end of the year. Lift-off on an Ariane 6 is planned in by Ariane Space for January 2027.

About Plato

ESA’s Plato (PLAnetary Transits and Oscillations of stars) will use 26 cameras to study terrestrial exoplanets in orbits up to the habitable zone of Sun-like stars.

Plato's scientific instrumentation, consisting of the cameras and electronic units, is provided through a collaboration between ESA and the Plato Mission Consortium composed of various European research centres, institutes and industries. The spacecraft is being built and assembled by the industrial Plato Core Team led by OHB together with Thales Alenia Space and Beyond Gravity.

On the launch anniversary of the NASA/ESA/CSA James Webb Space Telescope, ESA presents a unique compilation of zooms into stunning cosmic views.

So embark on a special journey: as if aboard a virtual spaceship, this video will take you through interstellar dives into the rich realm of our Universe. We will visit colourful nebulas and dynamic star nurseries in our own galaxy. Then venture beyond, to travel to the distant reaches of the cosmos and marvel at interacting galaxies and huge galaxy clusters.

The largest space telescope ever, Webb was launched on Christmas Day in 2021, on an Ariane 5 rocket from Europe's Spaceport in French Guiana. It performed its first scientific observations in July 2022. Since then, the powerful telescope has been tirelessly exploring the Universe, from the solar neighbourhood to the most distant galaxies.

Happy fourth anniversary, Webb!

ESA’s Jupiter Icy Moons Explorer (Juice) is on an epic eight-year journey to Jupiter. It left Earth in April 2023 and is due to arrive at the gas giant in 2031. 

2025 has been another big year for Juice. It made its closest approach to the Sun and flew close by Venus for a gravity boost to help it on its way. This second episode of ‘The journey of Juice’ takes us on a journey of our own, discovering what Juice – and the humans behind it – have experienced this year. 

In a clean room at ESA’s technical centre, thermal engineer Romain Peyrou-Lauge shows us the technologies that protect Juice from the intense heat of the Sun during this period. 

In Uppsala, Sweden, scientists get together for a ‘science working team’ meeting to discuss the scientific aspects of the mission. Juice Project Scientist Olivier Witasse talks about how important it is to continue working as a team to prepare for Juice’s precious time spent collecting data at Jupiter. 

The video culminates with operations engineer Marc Costa taking us to the Cebreros station in Madrid for the Venus flyby. There we meet deputy station manager Jorge Fauste, Juice intern Charlotte Bergot and Juice Mission Manager Nicolas Altobelli. 

This series follows on from ‘The making of Juice’ series, which covered the planning, testing and launch of this once-in-a-generation mission.