I really hope I live long enough to see scaled-up spectroscopy of exoplanets [1]. (I don't have enough optimism for hope for actual imaging.) It'll be fascinating to get a sense of the true range of world-types out there and see how often planets end up developing life.
(Picking up oxygen would be a high-confidence indicator of the presence of life, since oxygen reacts with everything and so can maintain a stable fraction of a planet's atmosphere only by continual replenishment, the only known mechanism for which is biological.)
(Picking up oxygen would be a high-confidence indicator of the presence of life, since oxygen reacts with everything and so can maintain a stable fraction of a planet's atmosphere only by continual replenishment, the only known mechanism for which is biological.)
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4156723/