Introducing the Voyage 2050 White Papers, contributions from the science community to ESA’s long-term plan for the Scientific Programme

The Scientific Programme is at the foundation of the European Space Agency, being the main “mandatory programme”, to which all Member States contribute by virtue of their being part of ESA. Member StatesFootnote 1 decide on the level of funding for the Scientific Programme by unanimous decision, and so far in ESA’s history they have shown their unwavering support to the Programme through a remarkably constant level of funding through the last three decennia. This long-term funding horizon has allowed the Programme’s stakeholders to decide and plan their priorities well in advance, providing the scientific community in Europe with a clear vision about which scientific areas deserve investment and development. Thanks also to this, the Programme has, since the 1980s, been planned in cyclesFootnote 2 of approximately 20 years durations, commensurate with the amount of time necessary to implement ambitious space missions. The first planning cycle, called Horizon 2000, was established in 1984, and consisted of a decision at the beginning of the cycle about the themes of the larger Programme elements (Cornerstones, or Large missions)Footnote 3, from which the SOHO, Cluster, Rosetta, XMM-Newton, and Herschel missions emerged. The smaller programme elements would be selected through peer review via open Calls for Missions implemented during the planning cycle. Horizon 2000 was followed by an update, called Horizon 2000 + in 1994–1995, with the addition of two Cornerstones, Gaia and BepiColombo, along with a number of smaller missions. A further planning cycle, Cosmic Vision, started to take shape in 2005, preparing the way for the implementation of the Large missions JUICE (to be launched in 2022), Athena and LISA (with launch dates in the 2030s), all three now firmly established in the Programme. It is thus high time to decide upon the future beyond Athena and LISA, and for this reason the Director of Science has initiated a new long-term planning cycleFootnote 4, with the name Voyage 2050, to decide what should be the scientific priorities of the Scientific Programme following Athena and LISA. The approach to long-term planning adopted for the Programme has shown its success by providing European scientists with the tools (space missions) to establish their leadership in a number of fields, and has established the Scientific Programme as a reference among space-faring actors worldwide