Searching for a Second Earth – PLATO’s Control Software Achieved a Critical Milestone

PLATO (PLAnetary Transits and Oscillations of stars) Spacecraft Control Software (SCSW) held Critical Design Review (CDR) on January 31, 2025. This marks an important milestone in its development. 

PLATO is a medium-class mission within European Space Agency ESA’s Cosmic Vision programme. It is designed to explore terrestrial planets orbiting up to the habitable zone of Sun-like stars. Its goal is to characterize these planets and their host stars by determining their radii, mass, and age. 

The spacecraft will travel to the Sun-Earth Lagrange Point 2, where it will seek to answer a fundamental question: Does a second Earth exist in the Universe? Equipped with 26 cameras, PLATO will achieve a high signal-to-noise ratio, enhancing its ability to detect Earth-like exoplanets. 

Exploring Exoplanets Through Global Collaboration 

At Lagrange point 2, the telescope will survey over 200,000 stars during its four-year nominal operation, looking for regular decreases in the brightness of these stars, which occur when a planet passes in front of them. By analysing these transits and studying the fluctuations in stellar brightness, researchers will be able to accurately determine the characteristics of exoplanets and the stars they orbit. 

Plato is an ESA-led mission, with German OHB System AG nominated as prime contractor. The spacecraft will be built and assembled by OHB together with Thales Alenia Space (France and the UK) and Beyond Gravity in Switzerland. Huld is the prime for Spacecraft Control Software under contract from Thales Alenia Space (France).  

“Huld designed the control software in collaboration with TAS-F and subsequently developed and validated it. In addition, our experts created both hardware and numerical software validation facilities to validate the control software. A highly skilled team contributed to the project, including 24 experts from Huld and 10 from subcontractors.”  Jussi Johansson, Project Manager, Huld.  

The development of the PLATO Spacecraft Control Software (SCSW) began in autumn 2018. It is expected to be completed by autumn this year, taking approximately seven years. The satellite is scheduled for launch at the end of 2026. 


Huld is a technology house employing 400 people in Finland and Czech Republic. We have decades of experience in demanding space and satellite applications. We provide mission-critical control systems for satellite platforms, and scientific processing in atmospheric sounding and imaging missions. Together with our clients we build intelligent solutions that last for tomorrow – and beyond.   

Picture: The PLATO satellite. © ESA/ATG Medialab