PLATO (spacecraft)

PLAnetary Transits and Oscillations of stars (PLATO) is a space telescope under development by the European Space Agency for launch in 2026. It is the third medium-class mission in ESA's Cosmic Vision programme and is named after the influential Greek philosopher Plato.

The mission goals are to search for planetary transits across up to one million stars, and to discover and characterize rocky extrasolar planets around yellow dwarf stars (like the Sun), subgiant stars, and red dwarf stars. The emphasis of the mission is on Earth-like planets in the habitable zone around Sun-like stars where water can exist in a liquid state. A secondary objective of the mission is to study stellar oscillations or seismic activity in stars to measure stellar masses and evolution and enable the precise characterization of the planet host star, including its age.

PLATO is an acronym, but also the name of a philosopher in Classical Greece; Plato (428–348 BC) was looking for a physical law accounting for the orbit of planets (errant stars) and able to satisfy the philosopher's needs for "uniformity" and "regularity".

The PLATO Mission Consortium (PMC), led by Prof. Heike Rauer at the German Aerospace Center (DLR) Institute of Planetary Research, is responsible for part of the payload and major contributions to the science operations. The Cameras are built by an international team from Italy, Switzerland and Sweden and coordinated by Isabella Pagano at INAF (Istituto Nazionale di Astrofisica). The Telescope Optical Unit development is funded by the Italian Space Agency, the Swiss Space Office and the Swedish National Space Board. The PMC Science Management (PSM), composed of more than 500 experts, is coordinated by Prof. Don Pollacco of the University of Warwick and provides expertise for:

The objective is the detection of terrestrial exoplanets up to the habitable zone of solar-type stars and the characterization of their bulk properties needed to determine their habitability. To achieve this objective, the mission has these goals:

PLATO will differ from the CoRoT, TESS, CHEOPS, and Kepler space telescopes in that it will study relatively bright stars (between magnitudes 4 and 11), enabling a more accurate determination of planetary parameters, and making it easier to confirm planets and measure their masses using follow-up radial velocity measurements on ground-based telescopes. Its dwell time will be longer than that of the TESS NASA mission, making it sensitive to longer-period planets.

The PLATO payload is based on a multi-telescope approach, involving 26 cameras in total: 24 "normal" cameras organized in 4 groups, and 2 "fast" cameras for bright stars. The 24 "normal" cameras work at a readout cadence of 25 seconds and monitor stars fainter than apparent magnitude 8. The two "fast" cameras work at a cadence of 2.5 seconds to observe stars between magnitude 4 to 8. The cameras are refracting telescopes using six lenses; each camera has a 1,100 deg² field and a 120 mm lens diameter. Each camera is equipped with its own CCD staring array, consisting of four CCDs of 4510 x 4510 pixels.

The 24 "normal cameras" will be arranged in four groups of six cameras with their lines of sight offset by a 9.2° angle from the +ZPLM axis. This particular configuration allows surveying an instantaneous field of view of about 2,250 deg² per pointing. The space observatory will rotate around the mean line of sight once per year, delivering a continuous survey of the same region of the sky.