Since we have no idea what the conditions that give rise to life are, how will we identify planets with similar ones?
Of course we have an idea of conditions required to sustain life, as we know it anyway.
The recent batch of exoplanets were all spotted with the High-Accuracy Radial-Velocity Planet Searcher (HARPS), a 3.6-metre telescope and spectograph
A spectroscope or spectograph aids in analyzing light to determine elements, gas and material present.