PLAnetary Transits and Oscillations of stars (PLATO) is aspace telescope under development by theEuropean Space Agency for launch in late 2026. It is the third medium-class mission in ESA'sCosmic Vision programme and is named after the influential Greek philosopherPlato.
The mission goals are to search for planetarytransits across up to one million stars, and to discover and characterizerockyextrasolar planets aroundyellow dwarf stars (like theSun),subgiant stars, andred dwarf stars. The emphasis of the mission is on Earth-like planets in thehabitable zone around Sun-like stars where water can exist in a liquid state.[4] A secondary objective of the mission is to study stellar oscillations orseismic activity in stars to measure stellar masses and evolution and enable the precise characterization of the planet host star, including its age.[5]
PLATO is an acronym, but also the name of aphilosopher inClassical Greece;Plato (428–348BC) was looking for aphysical law accounting for the orbit of planets (errant stars) and able to satisfy the philosopher's needs for "uniformity" and "regularity".[6]
The PLATO Mission Consortium (PMC), led by Prof. Heike Rauer at theGerman 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 theItalian Space Agency, theSwiss Space Office and theSwedish National Space Board.[3] The PMC Science Management (PSM), composed of more than 500 experts, is coordinated by Prof. Don Pollacco of theUniversity of Warwick and provides expertise for:
The preparation of the PLATO Input Catalogue (PIC)
Identifying the optimal fields for PLATO to observe
Coordinating follow-up observations
Scientifically validating PLATO's data products[7]
The objective is the detection ofterrestrial exoplanets up to thehabitable zone of solar-type stars and the characterization of their bulk properties needed to determine theirhabitability.[1][4] To achieve this objective, the mission has these goals:
Discover and characterize many nearbyexoplanetary systems, with precision in the determination of the planets' radii of up to 3%, stellar age of up to 10%, and planet mass of up to 10% (the latter in combination with on-groundradial velocity measurements)
Detect and characterize Earth-sized planets andsuper-Earths in thehabitable zone around solar-type stars
Discover and characterize manyexoplanetary systems to study their typical architectures, and dependencies on the properties of their host stars and the environment
Measurestellar oscillations to study the internal structure of stars and how it evolves with age
Identify good targets for spectroscopic measurements to investigateexoplanet atmospheres
PLATO will differ from theCoRoT,TESS,CHEOPS, andKepler 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-upradial velocity measurements on ground-based telescopes. Its dwell time will be longer than that of theTESS 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.[1] The 24 "normal" cameras work at a readout cadence of 25 seconds and monitor stars fainter thanapparent magnitude 8. The two "fast" cameras work at a cadence of 2.5 seconds to observe stars between magnitude 4 to 8.[1][8] The cameras arerefracting telescopes using six lenses; each camera has a 1,100 deg2 field and a 120 mm lens diameter. Each camera is equipped with its ownCCDstaring array, consisting of four CCDs of 4510 x 4510pixels.[1]
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 instantaneousfield of view of about 2,250 deg2 per pointing.[1] 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.
The public release of photometric data (including light curves) and high-level science products for each quarter will be made after six months and by one year after the end of their validation period. The data are processed by quarters because this is the duration between each 90-degree rotation of the spacecraft. For the first quarter of observations, six months are required for data validation and pipeline updates. For the next quarters, three months will be needed.[9]
A small number of stars (no more than 2,000 stars out of 250,000) will have proprietary status, meaning the data will only be accessible to the PLATO Mission Consortium members for a given time period. They will be selected using the first three months of PLATO observations for each field. The proprietary period is limited to 6 months after the completion of the ground-based observations or the end of the mission archival phase (Launch date + 7.5 years), whichever comes first.[9]
PLATO was first proposed in 2007 to theEuropean Space Agency (ESA) by a team of scientists in response to the call for ESA'sCosmic Vision 2015–2025 programme.[6]
The assessment phase was completed during 2009, and in May 2010 it entered the Definition Phase.
Following a call for missions in July 2010, ESA selected in February 2011 four candidates for a medium-class mission (M3 mission) for a launch opportunity in 2024.[6][10]
PLATO was announced on 19 February 2014 as the selected M3 class science mission for implementation as part of its Cosmic Vision Programme. Other competing concepts that were studied included the four candidate missionsEChO,LOFT,MarcoPolo-R andSTE-QUEST.[11]
In January 2015, ESA selectedThales Alenia Space,[12]Airbus DS, andOHB System AG to conduct three parallel phase B1 studies to define the system and subsystem aspects of PLATO, which were completed in 2016.
On 20 June 2017, ESA adopted PLATO in the Science Programme, which means that the mission can move from a blueprint into construction. Over the coming months, industry was asked to make bids to supply the spacecraft platform.[13]
In October 2018, ESA signed a contract withOHB System AG to lead the construction of PLATO.[14]
In January 2022, PLATO passed a critical milestone review and has been given the green light to continue with its development.[15]
From May to August 2023, a structural model of PLATO was undergoing a test campaign atESTEC Test Centre inNoordwijk to check if it can withstand the loads of the launch.[16]
In June 2024, the integration of PLATO's cameras has started at OHB facility inOberpfaffenhofen.[17]
In January 2025, ESA andArianespace signed the launch agreement to fly PLATO onAriane 6.[19]
In April 2025,ESOC's Ground Segment Reference Facility (GSRF) performed a series of radio tests to make sure that PLATO's communication system is capable of interacting with the ESA’sESTRACK deep space antennas.[20]
In May 2025, ESA announced that 24 of the 26 cameras have been installed at OHB. The remaining two are the "fast" cameras that will monitor the brightest stars and contribute to controlling the spacecraft's pointing.[21]
On 11 June 2025, PLATO's payload module, now including all 26 cameras, was connected to the service module.[22]
On 1 September 2025, PLATO arrived atESTEC in the Netherlands. It was transported fromOberpfaffenhofen via theRhine River by the VAARWEL cargo vessel.[23]
On 9 September 2025, PLATO has been completed atESTEC by installation of the combined sunshield and solar array module. Later in September, engineers tested the deployment and energy generation of the solar array wings.[24][25][26]
^abcIsabella Pagano (2014)."PLATO 2.0".INAF – Osservatorio Astrofisico di Catania. Archived fromthe original on 3 July 2019. Retrieved20 February 2014.
^PLATO: detailed design of the telescope optical units. Authors: D. Magrin, Ma. Munari, I. Pagano, D. Piazza, R. Ragazzoni, et al., inSpace Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave, Edited by Oschmann, Jacobus M., Jr.; Clampin, Mark C.; MacEwen, Howard A. Proceedings of the SPIE, Volume 7731, pp. 773124-8 (2010)
