PLATO (PLAnetary Transits and Oscillations of stars) is a space mission by the European Space Agency (ESA) dedicated to the discovery and characterization of extrasolar planetary systems. The mission was selected as the third medium-class mission — M3 — in ESA's Cosmic Vision program and is scheduled to launch in January 2027 on an Ariane 6 rocket from the European Spaceport in Kourou. The space telescope will then be placed into a halo orbit around the Sun-Earth Lagrange point L2, approximately 1.5 million kilometers from Earth.
PLATO focuses on small, particularly terrestrial exoplanets orbiting bright, sun-like stars — including planets in orbits extending into the habitable zone, the region where liquid water could exist on a planet's surface. PLATO will thus address central questions of modern astrophysics: How do planets and planetary systems form and evolve? Is our solar system unique? And how common are potentially habitable planets?
The mission utilizes the transit method: when a planet passes in front of its host star, it causes a tiny, periodic dimming of the starlight. These light curves allow scientists to derive the planet's size, orbital period, and orbital geometry, among other parameters. Combined with ground-based follow-up observations, particularly radial velocity measurements, planet masses and mean densities can also be determined. For Earth-like planets orbiting sun-like stars, PLATO aims for accuracies of about 5% for radius, 10% for mass, and 10% for age.
A unique feature of PLATO is its payload consisting of 26 cameras: 24 "normal" cameras are arranged in four groups and together cover a very large field of view; two "fast" cameras are used, among other tasks, for observing very bright stars and for fine navigation. In total, the camera payload includes 104 CCDs (four per camera) with 4510 × 4510 pixels. Through this multi-camera architecture, PLATO achieves a wide field of view along with a high signal-to-noise ratio, and will monitor more than 200,000 stars.
In addition to the search for exoplanets, asteroseismology is a core component of the mission. PLATO will measure minute variations in stellar brightness caused by stellar oscillations. From these, fundamental properties of the stars — specifically mass, radius, and age — can be determined with high precision. These stellar parameters are crucial for reliably contextualizing the properties of the orbiting planets.
PLATO will deliver a comprehensive, homogeneously analyzed catalog of well-characterized planetary systems. This catalog will enable comparative studies of planetary systems, provide new insights into planet formation and evolution, and identify suitable targets for future atmospheric investigations. In doing so, the mission builds on previous and ongoing exoplanet missions such as CoRoT, Kepler/K2, TESS, and CHEOPS, but expands their results particularly through the combination of long-duration photometric monitoring of bright stars, asteroseismology, and ground-based follow-up observations.
Contribution of the Rhenish Institute of Environmental Research
The Free Institute for Planetary Research (FIP), as part of the Rhenish Institute for Environmental Research, Cologne, is involved in the PLATO mission in various ways. Martin Pätzold and Sascha Grziwa are members of the PLATO Mission Consortium. The Free Institute for Planetary Research has previously participated in earlier missions for exoplanet detection (CoRoT, Kepler/K2, and TESS).
In addition to scientific research, the institute is involved in payload development and mission planning. This includes providing scientific and technical support for camera testing, as well as contributing to the preparation for commissioning and the subsequent operation of the cameras during the mission. Sascha Grziwa is a member of the Commissioning and Operations Core Team within both the PLATO PCOT (Payload Calibration and Operations Team) and the PPT (PLATO Performance Team). PCOT coordinates contributions to the characterization, calibration, and operation of the PLATO payload, including interfacing with ESA, supporting payload calibration, operational procedures, health monitoring, and trend analysis.
The PPT assesses instrument and science performance aspects across the entire mission, including science requirements, instrument performance, signal and noise budgets, as well as payload performance models. This work is essential for understanding PLATO's expected photometric precision and preparing the mission's scientific yield. Since mid-2025, Sascha Grziwa has been supported in these efforts by our newest member, Christian Dederichs.
Furthermore, Sascha Grziwa contributes to the scientific preparation of the mission as Co-Chair of the Early Science Working Group. The Early Science Working Group focuses on the early scientific utilization of PLATO data and handles the prioritization of initial data evaluations. The institute's involvement in the PLATO mission builds upon its long-standing experience in analyzing high-precision stellar light curves, searching for transit signals, and characterizing extrasolar planetary systems.
This project is funded by the Federal Ministry for Research, Technology and Space through the project sponsor German Space Agency Bonn under project number 50 OP 2102.
