Scientists have studied the possibility of life on Mars before the Viking missions. They identified four types of organisms that could survive on Mars based on temperature and water availability. The Viking lander experiments focused on one type of organism, but others could exist on Mars. Organisms that get water from minerals or ice could live there. The harsh conditions on Mars, like high UV radiation and low oxygen, might not stop life from existing. Even large organisms could thrive on Mars, and they might be visible to cameras. Scientists are discussing where Martian life could be found and how to search for it in the future.