ESO Top News

For decades, satellites have played a crucial role in our understanding of the remote polar regions. The ongoing loss of Antarctic ice, owing to the climate crisis, is, sadly, no longer surprising. However, satellites do more than just track the accelerating flow of glaciers towards the ocean and measure ice thickness.

New research highlights how ESA’s CryoSat mission has been used to uncover the hidden impact of subglacial lakes – vast reservoirs of water buried deep under the ice – that can suddenly drain into the ocean in dramatic outbursts and affect ice loss.

This image shows Webb’s recent observation of the asteroid 2024 YR4 using both its Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI). Data from NIRCam shows reflected light, while the MIRI observations show thermal light.

On 8 March 2025, the NASA/ESA/CSA James Webb Space Telescope turned its watchful eye toward asteroid 2024 YR4, which we now know poses no significant threat to Earth in 2032 and beyond.

This is the smallest object targeted by Webb to date, and one of the smallest objects to have its size directly measured.

Observations were taken to study the thermal properties of 2024 YR4, including how quickly it heats up and cools down and how hot it is at its current distance from the Sun. These measurements indicate that this asteroid does not share properties observed in larger asteroids. This is likely a combination of its fast spin and lack of fine-grained sand on its surface. Further research is needed, however this is considered consistent with a surface dominated by rocks that are roughly fist-sized or larger.

Asteroid 2024 YR4 was recently under close watch by the team at ESA's Near Earth Objects Coordination Centre, located in Italy. Planetary defence experts from the Agency's Space Safety programme worked with NASA and the international asteroid community to closely watch this object and refine its orbit, which was eventually determined to not pose a risk of Earth impact. Read details on this unusual campaign via ESA's Rocket Science blog and in news articles here and here.

Webb’s observations indicate that the asteroid measures roughly 60 meters (comparable to the height of a 15-story building).

The new observations from Webb not only provide unique information about 2024 YR4’s size, but can also complement ground-based observations of the object's position to help improve our understanding of the object’s orbit and future trajectory.

Note: This post highlights data from Webb science in progress, which has not yet been through the peer-review process.

[Image description: A collage of three images showing the black expanse of space. Two-thirds of the collage is taken up by the black background sprinkled with small, blurry galaxies in orange, blue, and white. There are two images in a column at the right side of the collage. On the right side of the main image, not far from the top, a very faint dot is outlined with a white square. At the right, there are two zoomed in views of this area. The top box is labeled NIRCam and shows a fuzzy dot at the center of the inset. The bottom box is labeled MIRI and shows a fuzzy pinkish dot.]

Space Debris: Is it a Crisis?

The European Space Agency’s short documentary film ‘Space Debris: Is it a Crisis?’ on the state of space debris premiered at the 9th European Conference on Space Debris on 1 April 2025.

Earth is surrounded by thousands of satellites carrying out important work to provide telecommunications and navigation services, help us understand our climate, and answer fundamental questions about the Universe.

However, as our use of space accelerates like never before, these satellites find themselves navigating increasingly congested orbits in an environment criss-crossed by streams of fast-moving debris fragments resulting from collisions, fragmentations and breakups in space.

Each fragment can damage additional satellites, with fears that a cascade of collisions may eventually render some orbits around Earth no longer useable. Additionally, the extent of the harm of the drastic increase in launches and number of objects re-entering our atmosphere and oceans is not yet known.

So, does space debris already represent a crisis?

The documentary explores the current situation in Earth’s orbits and explains the threat space debris poses to our future in space. It also outlines what might be done about space debris and how we might reach true sustainability in space, because our actions today will have consequences for generations to come.

ESA’s Space Safety Programme

ESA’s Space Safety Programme aims to safeguard the future of spaceflight and to keep us, Earth and our infrastructure on the ground and in space safe from hazards originating in space.

From asteroids and solar storms to the human-made problem of space debris, ESA works on missions and projects to understand the dangers and mitigate them.

In the longer term, to ensure a safe and sustainable future in space, ESA aims to establish a circular economy in space. To get there, the Agency is working on the technology development necessary to make in-orbit servicing and zero-debris spacecraft a reality.

Watch the video in other languages.

Read the latest edition of ESA Impact

Launched just seven months ago, ESA’s Arctic Weather Satellite has been proving how the New Space approach can accelerate the development of missions capable of delivering detailed temperature and humidity profiles for short-term weather forecasts.

Moreover, the impact of this tiny prototype satellite goes even further – its measuring instrument has been recognised as able to provide data that’s on a par with traditional large missions.

The European Space Agency (ESA) has selected Airbus to design and build the landing platform for the ExoMars Rosalind Franklin rover. In 2028, ESA will launch this ambitious exploration mission to search for past and present signs of life on Mars.

Meet Arnaud Prost—aerospace engineer, professional diver, and member of ESA’s Astronaut Reserve. From flying aircraft to getting a taste of spacewalk simulation, his passion for exploration knows no bounds.

In this miniseries, we take you on a journey through the ESA Astronaut Reserve, diving into the first part of their Astronaut Reserve Training (ART) at the European Astronaut Centre (EAC) near Cologne, Germany. Our “ARTists” are immersing themselves in everything from ESA and the International Space Station programme to the European space industry and institutions. They’re gaining hands-on experience in technical skills like spacecraft systems and robotics, alongside human behaviour, scientific lessons, scuba diving, and survival training.

ESA’s Astronaut Reserve Training programme is all about building Europe’s next generation of space explorers—preparing them for the opportunities of future missions in Earth orbit and beyond.

This interview was recorded in November 2024. 

You can listen to this episode on all major podcast platforms.

Keep exploring with ESA Explores!

Learn more about Arnaud’s PANGAEA training here.

Week in images: 24-28 March 2025

Discover our week through the lens

For over a decade, ESA’s Gaia mission has mapped our galaxy with stunning precision—rewriting the story of the Milky Way. As its mission enters a new phase, we look back at its most groundbreaking discoveries.

The first image from a new Italian Earth observation satellite mission was published today: a high-resolution image of a strip of the Italian peninsular showing the city of Rome at a resolution of 2.66 metres. This is three times higher than the resolution currently available for systematic acquisition over Italy.

Two spacecraft flying as one – that is the goal of European Space Agency’s Proba-3 mission. Earlier this week, the eclipse-maker moved a step closer to achieving that goal, as both spacecraft aligned with the Sun, maintaining their relative position for several hours without any control from the ground.

The European Space Agency (ESA) has powered down its Gaia spacecraft after more than a decade spent gathering data that are now being used to unravel the secrets of our home galaxy.

On 27 March 2025, Gaia’s control team at ESA’s European Space Operations Centre carefully switched off the spacecraft’s subsystems and sent it into a ‘retirement orbit’ around the Sun.

Though the spacecraft’s operations are now over, the scientific exploitation of Gaia’s data has just begun.

Using the unique infrared sensitivity of the NASA/ESA/CSA James Webb Space Telescope, researchers can examine ancient galaxies to probe secrets of the early Universe. Now, an international team of astronomers has identified bright hydrogen emission from a galaxy in an unexpectedly early time in the Universe’s history. The surprise finding is challenging researchers to explain how this light could have pierced the thick fog of neutral hydrogen that filled space at that time.

Aside from sunlight, the Sun sends out a gusty stream of particles called the solar wind. The ESA-led Solar Orbiter mission is the first to capture on camera this wind flying out from the Sun in a twisting, whirling motion. The solar wind particles spiral outwards as if caught in a cyclone that extends millions of kilometres from the Sun.

Solar wind rains down on Earth's atmosphere constantly, but the intensity of this rain depends on solar activity. More than just a space phenomenon, solar wind can disrupt our telecommunication and navigation systems.

Solar Orbiter is on a mission to uncover the origin of the solar wind. It uses six imaging instruments to watch the Sun from closer than any spacecraft before, complemented by in situ instruments to measure the solar wind that flows past the spacecraft.

This video was recorded by the spacecraft's Metis instrument between 12:18 and 20:17 CEST on 12 October 2022. Metis is a coronagraph: it blocks the direct light coming from the Sun's surface to be able to see the much fainter light scattering from charged gas in its outer atmosphere, the corona.

Metis is currently the only instrument able to see the solar wind's twisting dance. No other imaging instrument can see – with a high enough resolution in both space and time – the Sun's inner corona where this dance takes place. (Soon, however, the coronagraph of ESA's Proba-3 mission might be able to see it too!)

The research paper that features this data, ‘Metis observations of Alfvénic outflows driven by interchange reconnection in a pseudostreamer’ by Paolo Romano et al. was published today in The Astrophysical Journal.

Solar Orbiter is a space mission of international collaboration between ESA and NASA, operated by ESA.

[Technical details: The starting image of the video shows the full view of Solar Orbiter's Metis coronagraph in red, with an image from the spacecraft's Extreme Ultraviolet Imager in the centre (yellow). Zooming to the top left of this view, we see a video derived from Metis observations. The vertical edge of the video spans 1 274 000 km, or 1.83 solar radii. The contrast in the Metis video has been enhanced by using a ‘running difference’ technique: the brightness of each pixel is given by the average pixel brightness of three subsequent frames, minus the average pixel brightness of the three preceding frames. This processing makes background stars appear as horizontal half-dark, half-light lines. Diagonal bright streaks and flashes are caused by light scattering from dust particles close to the coronagraph.]