PLATO: Half of the cameras aligned and ready for integration into the satellite

The Centre Spatial de Liège (CSL) has just completed the alignment and vibration testing of half of the 26 cameras that will be aboard the PLATO space observatory. This delicate task relies on complex numerical models. This new mission of the European Space Agency (ESA), scheduled to be launched by the end of 2026, aims to study planets similar to ours.

T

he PLATO mission of the ESA aims to study Earth-like planets orbiting in the habitable zone of Sun-like stars. This mission utilizes precise measurements of star transits and oscillations to provide information about these planets and their planetary systems. Transits allow for the measurement of the planets' sizes, while star oscillations provide data on their mass and age, crucial for evaluating the characteristics of the hosted planets.

PLATO is the first satellite dedicated to the study of the universe to use a battery of telescopes rather than a single one. This approach allows for the observation of a large number of bright stars over extended periods with unparalleled precision and sensitivity. Each telescope of PLATO observes a field of view equivalent to about 5,200 times the surface area of the full moon. These telescopes are designed with special lenses to ensure optimal optical performance and resilience to space environments.

"PLATO comprises 26 cameras with very large field of view, each equipped with CCD detectors and front-end electronics," explains Christophe Grodent, CSL's commercial director. "These cameras observe at different cadences to meet scientific needs." PLATO is a medium-class mission of ESA's Cosmic Vision 2015-2025 program.

The design and production of PLATO's cameras involved scientists and engineers from 15 countries under ESA coordination. The cameras were assembled, aligned, and mechanically tested in specialized facilities at CSL in Liège before undergoing vibration and optical performance tests in other facilities in France, the Netherlands, and Spain. "Thirteen of the 26 cameras have already passed through our hands," says Aline Hermans, engineer and project manager for CSL. "One of the alignment complexities lies in that it is performed at room temperature, whereas the operational temperature is around -80°C. This leads to significant detector noise and requires considering thermal expansions with accuracies of only a few microns." The team works on two alignment lines simultaneously to progress as quickly as possible.

To date, 13 of the 26 flight cameras have been delivered to OHB System AG, the ESA's prime contractor for this mission. Integrating these cameras onto the optical bench of PLATO marks the beginning of the next phase of the mission. The completion of camera alignment and vibration testing at CSL is scheduled for the end of this year.