ESO Top News

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The Atomic Clock Ensemble in Space (ACES), ESA’s state-of-the-art timekeeping facility, is now installed on the Columbus laboratory of the International Space Station. This still image, captured by external cameras on the Station, shows ACES after installation. For 25 years, cameras on the Station have documented activities in orbit, providing real-time views of operations like this one – a rare and remarkable perspective from space. 

On 25 April, the Canadian Space Agency’s robotic arm carefully extracted ACES from the SpaceX Dragon trunk and secured it onto the Columbus External Payload Facility, next to ESA’s space storm hunter ASIM (Atmospheric-Space Interactions Monitor). Mounted on the Earth-facing side, ACES will connect with ground clocks worldwide as the Station orbits Earth sixteen times a day. 

Developed by ESA with European industry led by Airbus, ACES carries the most precise clocks ever sent to space: PHARAO, developed by the French space agency CNES, and the Space Hydrogen Maser from Safran Timing Technologies in Switzerland. Together with a sophisticated microwave and laser link, they will compare time between space and Earth with unprecedented accuracy, testing fundamental physics and advancing future time standards. 

In March 2025, ACES arrived at NASA’s Kennedy Space Center, where ESA, Airbus and NASA teams prepared the payload for flight. ACES launched on 21 April aboard a SpaceX Falcon 9 as part of the 32nd commercial resupply services mission to the International Space Station. Today, ACES was successfully switched on for the first time, establishing communications with ground control and stabilising its thermal systems in preparation for clock operations. 

A six-month commissioning phase now begins, after which ACES will embark on its two-year science mission, opening new frontiers in fundamental physics and timekeeping.

After years of careful design and preparation, ESA’s Earth Explorer Biomass satellite is set for launch tomorrow, 29 April at 11:15 CEST, aboard a Vega-C rocket from Europe’s Spaceport in French Guiana.

This groundbreaking mission will offer unprecedented insights into the state and evolution of the world’s forests. By mapping the woody material in Earth’s forests, this revolutionary satellite will play a crucial role in deepening our understanding of how forests influence the global carbon cycle.

The Atomic Clock Ensemble in Space (ACES), ESA’s state-of-the-art timekeeping facility, has been successfully installed on the International Space Station, marking the start of a new chapter in space-based precision science. 

Week in images: 21-25 April 2025

Discover our week through the lens

Image: Copernicus Sentinel-1 captured this radar image over French Guiana – home to Europe’s Spaceport in Kourou, where ESA’s Biomass mission is being prepared for liftoff on 29 April onboard a Vega-C rocket.

ESA's Biomass mission is on the launch pad at Europe’s Spaceport in Kourou, French Guiana. Don’t miss the live coverage of liftoff on Tuesday 29 April, on ESA WebTV. Coverage will start at 10:55 CEST with commentary live from Kourou and ESA’s European Space Operations Centre in Germany. The Vega-C rocket carrying Biomass is scheduled for liftoff at 11:15.

Image: Solar Orbiter’s widest high-resolution view of the Sun

On 28 March 2025, a powerful magnitude 7.7 earthquake struck central Myanmar, sending shockwaves through the region. While the country is still dealing with the devasting aftermath, scientists have used radar images from the Copernicus Sentinel-1 satellites to reveal a detailed picture of how the ground shifted as a result of the quake – offering new insights into the mechanics of the tectonic Sagaing Fault and the scale of the seismic rupture.

In celebration of the NASA/ESA Hubble Space Telescope’s 35 years in Earth orbit, an assortment of images that were recently taken by Hubble has been released today. This stretches from the planet Mars to images of stellar birth and death, and a magnificent neighbouring galaxy. After over three decades of scrutinising our Universe, Hubble remains a household word as the most well-recognised telescope in scientific history.

Video: 00:02:22

ESA’s state-of-the-art Biomass  mission has been designed to shed new light on the health and dynamics of the world’s forests, revealing how they are changing over time and, critically, enhancing our understanding of their role in the global carbon cycle. It is the first satellite to carry a fully polarimetric P-band synthetic aperture radar for interferometric imaging. Thanks to the long wavelength of P-band, around 70 cm, the radar signal can slice through the forest canopy and whole forest layer to measure the ‘biomass’, meaning the woody trunks, branches and stems, which is where trees store most of their carbon.

A new wave of ocean scientists has embarked on an extraordinary six-week voyage aboard a majestic tall ship that set sail today from Norway bound for southern France. But this is no ordinary journey.

Thanks to this ESA Advanced Ocean Training Course, these upcoming researchers will be taking a deep dive into ocean science, empowering them with skills to harness satellite data for research, innovation and sustainable development – and preparing them to become tomorrow’s leaders and ambassadors for ocean science.

The European Space Agency has joined the world space community in congratulating the African Space Agency on its official inauguration. The African Space Agency (AfSA) is the second regional space agency after ESA and has been in development since 2015, with the African Union Commission adopting an African space policy and strategy in 2016.

Biomass mission kit

Explore ESA's forest mission

Video: 00:06:15

English

From 7 to 11 April, ESA's Centre for Earth Observation in Frascati, ESRIN, hosted the 2025 edition of ESA School Days, welcoming almost 1400 young students.

The event kicked off with primary school students (4th and 5th grades) visiting during the first three days, followed by secondary school students on the final two days.

Throughout the week,  35 schools from across Italy engaged in presentations and laboratories, delving into the diverse space activities conducted at ESA’s establishment.

This initiative, which included contributions from ESERO Italia and the Italian Space Agency (ASI), aims to inspire and engage the next generation of STEM students by sharing knowledge about space and the European Space Agency.

Italian

Dal 7 all'11 aprile, ESRIN, il Centro per l'Osservazione della Terra dell'ESA a Frascati, ha ospitato l'edizione 2025 degli ESA School Days, accogliendo quasi1 400 giovani studenti. L'evento ha preso il via con la visita degli studenti delle scuole primarie (classi quarte e quinte) durante i primi tre giorni, seguiti dagli studenti delle scuole secondarie nei due giorni finali.

Per tutta la settimana, 35 scuole da tutta Italia si sono cimentate in presentazioni e laboratori, approfondendo la loro conoscenza delle diverse attività spaziali condotte presso lo stabilimento dell'ESA.

L'iniziativa, che ha visto il contributo di ESERO Italia e dell'Agenzia Spaziale Italiana (ASI), mira a ispirare e coinvolgere la prossima generazione di studenti STEM condividendo le conoscenze sullo spazio e sull'Agenzia Spaziale Europea.

Image: This very high-resolution image captures the Egyptian city of Giza and its surrounding area, including the world-famous Giza Pyramid Complex.

Satellite observations show that sea-surface temperatures over the past four decades have been getting warmer at an accelerated pace.

Registrations are now open for the European Space Agency’s Living Planet Symposium (LPS) – one of the largest Earth observation conferences in the world. The event will take place on 23–27 June 2025 in Vienna, Austria.

Each year, cutting-edge technologies developed by the European Space Agency (ESA) for its complex missions and scientific discoveries find new life in applications used to benefit Earth and improve our daily lives.

From 9–13 April, ESA was guest of honour at the 50th International Exhibition of Inventions Geneva in Switzerland with more than 1000 inventions, which attracted 30 000 visitors from the public. ESA showcased its new technologies and applications that have been invented for space missions and patented for use in and outside the space arena.

Image: Sombrero Galaxy