Space astrometry: the Hipparcos and Gaia missions

Alone amongst the space agencies, ESA made its entry into space astrometry with the adoption of the Hipparcos mission in 1981. Outside of the astrometric community, it was viewed at the time as fundamental if not particularly exciting, although Freeman Dyson described it as "... the first time since Sputnik in 1957 that a major new development in space science has come from outside the US". In his ASP Millennium Essay in 2001, Cavendish Professor Malcolm Longair stated that "It is invidious to single out surveys which I find particularly impressive, but I make an exception for the Hipparcos astrometric satellite".

Hipparcos delivered its high-accuracy catalogue of 120,000 star distances and space motions in 1997. As a follow-up, ESA accepted the Gaia mission in 2000. Launched in 2013 and expected to operate into the next decade, Gaia will represent a revolution in its dynamical stereoscopic mapping of our Galaxy, promising a catalogue of more than a billion stars to 20 magnitude at microarcsec-level accuracy.

The talk will provide a short historical context and describe the scientific motivation for these missions, outline the essential experimental principles which underpin their measurements, and give an overview of the science objectives, including Gaia's expected yield of many thousands of astrometrically-detected exoplanets.

16/03/2017 - 12:30
Prof. M. Perryman
European Space Agency