PLATO has been given the green light to continue with its development after the critical milestone review concluded successfully on 11 January 2022. The review verified the maturity of the complete space segment (spacecraft platform and payload module), confirming the solidity of the spacecraft-to-payload interfaces, the payload schedule with particular focus on the series production of the 26 cameras, and the robustness of the spacecraft schedule. The critical milestone review was established specifically for PLATO at the time of mission adoption because of the development risks associated with the series production of the cameras.
The design of the spacecraft is stable since the Preliminary Design Review in March 2020. The thermo-elastic properties of the optical bench, which hosts the cameras, were verified with a novel test technique developed by the spacecraft prime contractor, OHB System AG. The Structural Thermal Model (STM) of the Payload Module has been manufactured and is undergoing the environmental mechanical and thermal test campaign at the ESTEC Test Services.
Nearly all aspects of the cameras production, assembly, and testing have been exercised successfully with the tests of structural, engineering and qualification models of the camera units carried out at several European facilities. The vibration and thermal vacuum tests of the Structural Thermal Model (STM) of a single camera was successfully completed at ESTEC. The first Engineering Model of a fully functional camera has been integrated and tested under ambient conditions and is now undergoing thermal-vacuum tests.
To date ESA has received flight model CCDs for all the cameras.
The PLATO (PLAnetary Transits and Oscillations of stars) mission was first proposed in 2007 as a medium-sized (M-class) candidate in response to the call for missions of the Cosmic Vision 2015-2025 programme for a launch in 2017-2018. The proposal was submitted by Dr Claude Catala (Observatoire de Paris, France) on behalf of a large consortium comprising scientists from laboratories across Europe.
Following favourable reviews by ESA's scientific advisory bodies, PLATO was selected in 2007 as one of the missions for which an ESA assessment study was carried out in 2008 and 2009. The PLATO mission was subsequently selected for a definition study, starting in February 2010.
After the non-selection of PLATO in October 2011 for the M1 or M2 launch opportunities, the ESA Science Programme Committee (SPC) endorsed the solicitation of a proposal to the PLATO Mission Consortium to be a candidate for the M3 launch opportunity. The PLATO Mission Consortium responded with a proposal for the provision of the payload and science ground segment components formulated in the M3 mission framework — this was accepted by ESA. A major change was the transfer of the leading role from France to Germany, with Professor Heike Rauer (DLR, Germany) as the new PLATO Principal Investigator.
In February 2014, the SPC selected PLATO as the M3 mission of the Cosmic Vision programme. This paved the way for the mission Definition Study which involved three concurrent industrial contracts with Airbus DS, OHB, and Thales Alenia Space. This activity covered the definition of the mission profile, the satellite, and parts of the payload module.
In addition, ESA performed the study of the PLATO science ground segment contribution and, together with e2v, of the CCDs procurement. The PLATO Mission Consortium carried out the study of the payload and of their contributions to the science ground segment.
The Definition phase concluded in May 2016 with the successful Payload, Science Ground-segment and Science Performance System Requirement Review (PSRR), and the Mission Adoption Review (MAR). The resulting science case and mission design are summarised in the Definition Study Report (ESA-SCI(2017)1).
In June 2016, the SPC approved the PLATO Science Management Plan.
The adoption of PLATO as the M3 mission in the Cosmic Vision Programme was approved by the Science Programme Committee in June 2017.
On 7 July 2017 ESA released an Invitation to Tender (ITT) for the design, development, and support to launch and post-launch operations (phases B2/C/D/E1) of the PLATO spacecraft. In parallel, ESA awarded the procurement contract for the cameras CCDs to Teledyne e2v. The Mission Consortium initiated the development phase for the payload and for their contribution to the Science Ground Segment.
The industrial development phase started on 4 October 2018 with the signature of the prime industrial contract with OHB System AG. The spacecraft will be built and assembled by OHB together with Thales Alenia Space (France and the UK) and RUAG Space Switzerland; many ESA member States will also be involved. The contract covers the delivery of the satellite, including the testing phase leading to launch, support during the launch campaign, and the in-orbit commissioning phase.
The Mission Preliminary Design Review (PDR) was declared successful in October 2020.