After some self research:
SIM was an ambitious mission concept of optical interferometer in space.
SIM was in development in period of 1998-2010 (in late years - as downsized SIM-Lite concept).
The main science themes SIM was planned to address:
How rare are Earth-like planets around closest stars (in habitable zone)
How abundand are exoplanets in ...
The first precision formation flying mission is ESA's Proba-3, slated for launch in 2018.
Proba-3 is ESA’s – and the world’s – first precision formation flying mission. A pair of satellites will fly together maintaining a fixed configuration as a ‘large rigid structure’ in space to prove formation flying technologies.
The mission will demonstrate formation ...