The meeting will take place in Kasteel Oud Poelgeest near Leiden, the Netherlands, about 15 minutes drive from Amsterdam Schiphol airport:

Kasteel Oud Poelgeest can be reached by taxi from Schiphol airport (~70 Euro), or by train to Leiden Central station followed by a 5 min taxi ride (~20 Euro total).

International efforts play a key role in driving all areas of astrophysics, and involve data access, facility access, and joint partnerships on large-scale instruments, observatories, and missions. Global cooperation and collaboration are becoming increasingly important to the field as the costs and preparation to build forefront facilities escalate. Multi-wavelength observations, surveys with follow-up observations, and time domain studies all lend themselves to coordinated approaches to astronomical research. In order to maximize the scientific return from facilities, global strategic planning and discussions are a logical part of the process in developing long-term future efforts. For this reason, the International Astronomical Union (IAU) established in 2016 the 'Working Group on Global Coordination of Ground and Space Astrophysics'� reporting directly to the Executive Committee. A key part of its activities is to organize meetings to foster international planning. This Kavli Workshop will be the first such meeting, for which a focus on the next generation optical telescopes in space has been chosen.

With the upcoming launch of the James Webb Space Telescope and the Hubble Space Telescope nearing its 4th decade of operations, astronomers are beginning to contemplate the next steps in space-based astronomy. A large UV/optical/IR telescope could image extrasolar planets and characterize their atmospheres, trace the formation history of our Galaxy and nearby galaxies, study ancient galaxies, and detect the first stars. Should the next space telescope be a modest step beyond our current capabilities (4-6 meters) or should we take the leap towards more ambitious and powerful telescopes (8-20 m)? Regardless, any future mission is likely to be an intercontinental effort. The goal of this workshop is to bring together international leaders to discuss science goals, technical requirements, and political constraints and opportunities. The meeting will attract experts on various aspects of the science program, technologists, space agency staff and science community leaders.

We plan to have a three-day workshop in the Netherlands in late July 2017 with about 40 participants. One of the products of the meeting would be a white paper outlining the case for these missions. This workshop would provide input to a special session of the 2018 IAU General Assembly focused on international collaboration. Another goal of the meeting is to fertilize the discussions about the ESA's future missions, the US 2020 astrophysics decadal survey, and other long-term prioritization processes across the globe. Since all these activities are starting in the coming 1-2 years, a meeting in mid-2017 is optimally timed. The ultimate aim of the meeting is to enable the development of ambitious joint space missions.