The PLATO mission, planned for launch in late 2026, represents a significant step forward in the search for rocky, Earth-like planets outside our Solar System.

Scientific Goals of the Mission
PLATO (PLAnetary Transits and Oscillations of stars) will use 26 cameras to study exoplanets in orbits within the habitable zone of Sun-like stars. The mission will measure the sizes of exoplanets and detect exomoons and rings around them, while simultaneously characterizing host stars by studying small variations in the light they receive.

Launch and Operations
The launch is planned from the European Spaceport in French Guiana, using an Ariane 6 rocket. PLATO will be placed in a halo orbit around the Sun-Earth Lagrange point L2, which will allow it to continuously observe the same part of the sky throughout the year.

Technical Aspects
PLATO will use 24 "normal" cameras (N-CAM) and 2 "fast" cameras (F-CAM). The N-CAMs are arranged in four groups of six cameras each, with each group of cameras having slightly different angles, providing a wide field of view of 2250 square degrees per direction. This arrangement allows PLATO to recognize false positive signals that could mimic the transit of an exoplanet.

Manufacturing and Testing
Most of the spacecraft components have passed the production phase and calibration tests are currently being conducted. The Mullard Space Science Laboratory at UCL in the UK has developed the front-end electronics (FEE) that control the cameras, digitize images, and transmit them for data processing. Ten final cameras have already been built and tested, with the first one mounted on the optical bench earlier this year.

Scientific Meetings and Collaborations
The PLATO mission will be a key topic at many scientific meetings. For example, the ESP2024 meeting: PLATO Planetary Systems – formation to observed architectures, held in May 2024 in Catania, brought together leading scientists to discuss current knowledge about exoplanetary systems and the mission's goals. PLATO will combine transit methods with the study of the internal structure of stars using stellar seismology, supported by extensive ground-based observations. This integrated approach will enable precise determination of exoplanet parameters, including their ages, which is crucial for understanding planetary evolutionary paths.

Predictions and Expectations
According to the most conservative planet population models, PLATO is expected to discover at least 500 Earth-sized planets during the nominal mission duration of four years. These predictions include all types of stars and distances from stars. For example, for Earth-sized planets with orbital periods of 250-500 days around G stars (Sun analogs), up to 12 discoveries are expected during two years of observations.

In the past 20 years, the number of known exoplanets has grown exponentially, with over 5,483 confirmed discoveries in 4,087 systems (and another 9,770 candidates awaiting confirmation). The discovery and characterization of these exoplanets have informed and challenged existing theories of planet formation and occurrence rates, but many scientific questions remain unanswered.

PLATO's results will help narrow the search for potentially habitable worlds, providing crucial information for assessing the frequency of Earth-like planets orbiting G-type solar analogs.

Source: Royal Astronomical Society