Astrobiology is arguably one of the main current drives in astronomy.
Projects have been devised by agencies as far back as the early 70's, well before the formal proof of the existence of exoplanets (1995).
Since, the field has known accelerating changes, simpler and more "opportunistic" techniques challenging projects not quite yet technologically ready. I will present the transition and the complementarily between these two strategies, which occurred roughly in 2007. The emphasis will be on the connection point between instrumental and theoretical aspects: i.e. current developments in signal processing techniques, and in the estimation of the characterization performance of the now less and less putative habitable exoplanets, with upcoming or under-development facilities.