Astrometry history: Roemer and Gaia

TL;DR

This paper reviews the historical development of astrometric missions from Roemer to Gaia, highlighting technological evolution and strategic decisions that shaped ESA's astrometry program.

Contribution

It details the transition from interferometric Gaia to the large Roemer design and its impact on ESA's astrometry mission planning.

Findings

Transition from interferometric Gaia to large Roemer in 1998

Interferometric Gaia influenced ESA's selection of the astrometry mission

Gaia's design evolution significantly impacted astrometric capabilities

Abstract

During the Hipparcos mission in September 1992, I presented a concept for using direct imaging on CCDs in scanning mode in a new and very powerful astrometric satellite, Roemer. The Roemer concept with larger aperture telescopes for higher accuracy was developed by ESA and a mission was approved in 2000, expected to be a million times better than Hipparcos. The present name Gaia for the mission reminds of an interferometric option also studied in the period 1993-97, and the evolution of optics and detection in this period is the main subject of the present report. The transition from an interferometric GAIA to a large Roemer was made on 15 January 1998. It will be shown that without the interferometric GAIA option, ESA would hardly have selected astrometry for a Cornerstone study in 1997, and consequently we would not have had the Roemer/Gaia mission.