Like, how long would it take to figure out if there is life on Earth? Clue: Bacteria live at high altitudes and latitudes that few even notice. Here on the level ground we kill zillions of life forms every time we wash our hands or sterilize a piece of equipment. And no one cares because there are plenty more where they came from.
If a planet has life, you will know, pretty quickly.
Origin: dark-shadowy-line.blogspot.com