CART before the Horse. First you have to find a site, out of several trillions. Not an optimal search program.

The BEST is finding a very large planet, in the liquid water temps/zone, with unstable organic cmpds. & spectra, which ID such substances, clearly, and confirmably. Something which looks like Chlorophyll or the other pigments found from plants.

Then we look for the living systems creating that, if possible.

Then we go from there. It's not the Wizard of Oz ideas.

As Ellie's dad said in Contact " Slow steps, ellie, Slow steps."