After 64 years dedicated to astrometric instrumentation, a Gaia successor is in sight
Niels Bohr Institute, Copenhagen, Denmark
The astrometric foundation of astrophysics has been enormously improved by two ESA satellites that determined the positions, distances and motions of stars. I was fortunate to be at the right place and right time so that I could contribute towards various developments after beginning work as a student in 1953 at a new Danish meridian circle. These include the designs of: a new method of astrometry by photon counting for the Hamburg meridian circle in 1960; a new design for the Hipparcos mission in 1975; the Tycho experiment for the Hipparcos satellite in 1981; direct-imaging on CCDs for the Gaia mission in 1992; and most recently, a Gaia successor in 2013 that should be launched in about twenty years. In April 2017 ESA approved our proposal (Hobbs et al. 2016, arXiv 1609.07325) to study a Gaia successor with infrared detecting capabilities. That proposal was one of three selected out of 26 submitted in response to ESA's call for new "Science Ideas" to be investigated for feasibility and technological developments.