ESA’s PLATO space telescope completes a key phase on its journey to search for exoplanets

Over the past 15 years, high-precision photometric space missions developed by the world’s leading space agencies have driven significant advances in stellar physics and exoplanet science. In this context, the pioneering PLATO mission has been designed to discover potentially habitable planets around stars similar to our Sun. Its goal is to study thousands of exoplanets in detail, with a special emphasis on terrestrial-type planets – rocky and composed mainly of silicon, oxygen and metals – in contrast to gas giants such as Jupiter or Saturn.

“PLATO, with its large field of view and unprecedented precision, will allow us to characterise Earth-like exoplanets and lay the scientific foundations for understanding our place in the universe”, says Javier Pascual, head of the Stellar Variability Group at the Institute of Astrophysics of Andalusia (IAA-CSIC) and member of the PLATO Spain consortium.

In June 2025, the PLATO mission reached a key milestone: the two main components of its telescope were integrated at the facilities of the aerospace and technology company OHB in Oberpfaffenhofen, Germany.

“Almost eight years after ESA gave the green light to the PLATO mission, both the satellite and its unique telescope with 26 ‘eyes’ have been completed as planned”, says Heike Rauer, scientific director of the mission from the German Aerospace Center (DLR) and the Freie Universität Berlin. “It is an extraordinary achievement. Unlike many other space telescopes, PLATO does not rely on a single complex camera, but will operate with a total of 26 cameras”.

This innovative system will enable PLATO to observe around 250,000 stars in search of planets that may be orbiting them. The cameras have been built and tested by different member countries of the PLATO Mission Consortium (PMC). “The international cooperation between the PMC and ESA has worked exemplary. All tests carried out so far indicate that PLATO will achieve the planned and necessary measurement accuracy”, adds Rauer.

A Crucial Step Before Launch

At OHB’s facilities in Bavaria, Germany, the PLATO space telescope has successfully completed one of its most delicate phases: the integration of its 26 scientific cameras and the platform housing all the acquisition, processing and control electronics for the instrument. The cameras were previously assembled on an optical platform, where they were installed with millimetre precision on the spacecraft’s service module, which contains the control, propulsion, communication and data management systems.

After carefully aligning both structures and verifying all electrical and communication connections, the technical team permanently joined the telescope to the service module. In the coming weeks, the spacecraft will undergo comprehensive functional tests to ensure the proper operation of the telescope and its data processing systems.

The next step will be its transfer to ESA’s European Space Research and Technology Centre (ESTEC) in the Netherlands, where solar panels and thermal shields will be installed. Afterwards, PLATO will undergo testing under space-like conditions before its final shipment to Kourou, French Guiana, from where it will take off on board an Ariane 6 rocket in December 2026.

Spain’s Contribution to the PLATO Mission

Spain’s contribution to the PLATO mission is vital both technologically and scientifically. Spain is participating in the development of the on-board computers that will process all images and scientific data, led by the Institute of Astrophysics of Andalusia (IAA-CSIC); in the thermomechanical structures of the telescope’s 26 cameras, developed by the Centre for Astrobiology (CAB-CSIC/INTA); and in the thermal vacuum calibration of ten of these cameras, carried out by the National Institute for Aerospace Technology (INTA). Spain is also contributing to the development and implementation of innovative tools for ground-based processing, analysis and management of the data generated by the satellite during the four years following its launch.

The PLATO Spain consortium is made up of seven leading research centres: the Institute of Astrophysics of Andalusia (IAA-CSIC), the Institute of Astrophysics of the Canary Islands (IAC-CSIC), the Centre for Astrobiology (CAB-CSIC/INTA), the National Institute for Aerospace Technology (INTA), the Institute of Space Sciences (ICE-CSIC), the University of Granada (UGR) and the University of Valencia (UV).

The University of Valencia node is focusing its contribution to the PLATO mission on the development of software for processing the data obtained directly from the observations. This means that the end users of the light curves will receive data corrected for unwanted physical effects, facilitating stellar analysis. This software provides a preliminary analysis that extracts relevant physical parameters for various scientific applications.

Further analysis of these data for use in asteroseismology incorporates non-linear analysis techniques, enabling a more accurate representation of stellar physics compared to classical linear approaches.

The researchers involved in this node are Andrés Moya Bedón and Miriam Rodríguez Sánchez, from the GRACE group of the Department of Astronomy and Astrophysics.

26 Cameras Scanning the Milky Way

Thanks to its unique design – with 26 cameras mounted on a common platform – the PLATO mission will observe around 250,000 stars in search of planets orbiting them. To do this, it will be sent to the L2 Lagrange Point of the Sun-Earth system, located 1.5 million kilometres from Earth, a region of space where the James Webb Space Telescope is also located.

PLATO is expected to discover thousands of new worlds – rocky, icy and gaseous – around different types of stars. To detect them, it will use the transit method, which consists of recording tiny, periodic decreases in a star's brightness caused by a planet passing in front of it.

Once these candidate planets are identified, they will be studied in greater detail from Earth through complementary observations and other techniques, such as radial velocity measurements, which reveal the mass of the planets and confirm their existence.

Reference:

https://www.esa.int/Science_Exploration/Space_Science/Plato/Plato_grows_its_many_eyes

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