Evaluating the Gaia Contribution to the Field of Eclipsing Binaries with Ground-Based Spectroscopy and Hipparcos Photometry

During its definition phase, ESA's Cornerstone mission Gaia was design to perform extremely accurate photometry in 10 medium plus 5 broad bands and to collect about 90 epoch spectra with a resolving power of 11,500 and a wavelength range 8480-8740 Å (centered on the CaII triplet in the far red). Combining epoch photometry from the Hipparcos mission with ground-based spectra strictly simulating Gaia ones, we have investigated in a series of papers the performance expected from Gaia on SB2 EBs (Munari et al. 2001, Niarchos and Manimanis 2003, Zwitter et al. 2003, Marrese et al. 2004, Milone et al. 2005). We review here the results we obtained. The Gaia design is now under major revision, and its impact on EBs will be briefly addressed.