When we will find aliens?

Chris McKay’s quest for extraterrestrial life started in 1976, when Viking 1 and 2 landed on Mars. Touching down on Mars for the first time was a big deal, sure, but the then-first-year graduate student was especially excited because the landers found what appeared to be signs of Martian life.

The spacecraft found that something in the dirt – possibly microbes – was taking in nutrients and producing gases like carbon dioxide. But when instruments failed to find any organic molecules, which are the building blocks of any organism, scientists concluded that no, aliens weren’t living in the dirt.

To this day, however, scientists like McKay are still baffled by the Viking data, which never conclusively supported the existence of life, but were tantalizing nevertheless. For McKay, now a planetary scientist at NASA Ames Research Center, those results launched a career in astrobiology, despite the warnings of other scientists at the time. “Not only did they tell me not to,” he says, “they made fun of me for being interested in it.”