PLATO (PLAnetary Transits and Oscillations of stars)

Its objective is to find and study a large number of extrasolar planetary systems, with emphasis on the properties of terrestrial planets in the habitable zone around solar-like stars. PLATO has also been designed to investigate seismic activity in stars, enabling the precise characterisation of planet-hosting stars, including their ages.

In order to achieve its science goals, the PLATO instrument concept is based on a multi-telescope approach comprising a set of 24 ‘normal’ cameras and a set of 2 ‘fast’ cameras. These will perform ultra-precise, uninterrupted photometric observations of hundreds of thousands of stars over a period of several years, trying to detect tiny dips in the light coming from them as candidate exoplanets transit in front of them. PLATO is currently scheduled to launch in early 2027 for a 4.5-year nominal mission.

PLATO will provide accurate, precise determinations of planetary radii and stellar properties (radii, masses, ages), along with estimates of stellar irradiation experienced by planets. In combination with ground-based observations, PLATO will also provide accurate planetary masses and mean densities. Together, these results will enable exploration of the architectures of planetary systems and their evolution through time.

The overall scientific questions that the mission will investigate are:

1. How do planets and planetary systems form and evolve?
2. Is our Solar System special or are there other systems like ours?
3. Are there potentially habitable planets?

The scientific objectives that PLATO will address are the following:

• Determine the bulk properties (mass, radius, and mean density) of planets in a wide range of systems, including terrestrial planets in the habitable zone of solar-like stars
• Study how planets and planet systems evolve with age
• Study the typical architectures of planetary systems
• Analyse the correlation of planet properties and their frequencies with stellar parameters (e.g., stellar metallicity, stellar type)
• Analyse the dependence of the frequency of terrestrial planets on the environment in which they formed
• Study the internal structure of stars and how it evolves with age
• Identify good targets for spectroscopic follow-up measurements to investigate planetary atmospheres. These planets will provide a wealth of information by which to study planetary formation and evolution and, for terrestrial planets, study potential habitability.

UK involvement

The UK plays a critical part in the overall delivery of this mission and hold lead roles on PLATO. Particularly, Prof Don Pollacco of the University of Warwick leads the PLATO Science Management team, is head of PLATO’s exoplanet science programme, and sits on the PLATO Consortium Board, whilst UCL’s Mullard Space Science Laboratory (MSSL) led the design and build of the electronics for the ‘normal’ cameras. Additionally, the CCD detectors are being manufactured under contract to the European Space Agency by Teledyne e2v in Chelmsford. Furthermore, the University of Cambridge heads the UK arm of the PLATO Data Centre and leads development and operations of the PLATO data processing pipelines for exoplanet science, while the University of Birmingham is responsible for an essential piece of PLATO’s stellar science programme.  The Open University, the University of Oxford, the University of St Andrews, and Keele University are also contributing to PLATO Science Management and Data Centre activities.

These varied roles in both the PLATO hardware development and ground segment ensure that UK researchers remain at the forefront of world class scientific research. Holding the science leadership role for PLATO will secure maximum science return on UK investment from the data produced by this cutting-edge science mission, building on UK research strengths and allowing the UK to maintain its international competitiveness in world class scientific research. The search for planets which could support alien life will generate significant public interest and outreach opportunities, encourage uptake of STEM subjects and inspiring the next generation of UK researchers and engineers.

Thales Alenia Space UK was selected as a partner to industry prime contractor OHB, building the spacecraft platform and service module for the science instrument. TAS-UK was involved in avionics development and service module integration.