PLATO (spacecraft)

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". == Background ==

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. == Objective ==

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: • Discover and characterize many nearby exoplanetary 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-ground radial velocity measurements) • Detect and characterize Earth-sized planets and super-Earths in the habitable zone around solar-type stars • Discover and characterize many exoplanetary systems to study their typical architectures, and dependencies on the properties of their host stars and the environment • Measure stellar oscillations to study the internal structure of stars and how it evolves with age • Identify good targets for spectroscopic measurements to investigate exoplanet atmospheres 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. ==Design==

Optics 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 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. == Data release schedule ==

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. == Project timeline ==

Development • Plato was first proposed in 2007 to the European Space Agency (ESA) by a team of scientists in response to the call for ESA's Cosmic Vision 2015–2025 programme. • 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 missions EChO, LOFT, MarcoPolo-R and STE-QUEST. • In January 2015, ESA selected Thales Alenia Space, Airbus DS, and OHB 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. • In October 2018, ESA signed a contract with OHB System AG to lead the construction of Plato. • In January 2022, Plato passed a critical milestone review and has been given the green light to continue with its development. Construction • From May to August 2023, a structural model of Plato was undergoing a test campaign at ESTEC Test Centre in Noordwijk to check if it can withstand the loads of the launch. • In June 2024, the integration of Plato's cameras has started at OHB facility in Oberpfaffenhofen. • In September 2024, UCL's Mullard Space Science Laboratory has delivered the read-out electronics for PLATO's cameras to the Liege space centre in Belgium. • In January 2025, ESA and Arianespace signed the launch agreement to fly PLATO on Ariane 6. • 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’s ESTRACK deep space antennas. • 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. • On 11 June 2025, Plato's payload module, now including all 26 cameras, was connected to the service module. • On 1 September 2025, Plato arrived at ESTEC in the Netherlands. It was transported from Oberpfaffenhofen via the Rhine River by the VAARWEL cargo vessel. • On 9 September 2025, Plato has been completed at ESTEC 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. Testing • In January 2026, Plato successfully passed vibration and acoustic tests at ESTEC. • On 18 February 2026, Plato was placed in the Large Space Simulator (LSS) for environmental testing, which started in early March 2026. • In April 2026, Plato has successfully completed its tests in LSS. Launch Plato is scheduled to be launched in January 2027 on an Ariane 62 to the Sun–Earth Lagrange point. == See also ==