As the climate crisis on Earth worsens, some Americans — including the world’s richest man, Elon Musk — have begun to think about a plan (and planet) B. They dream of escaping an increasing polluted Earth in favor of creating an advanced society on our nearest neighbor, Mars.

To investigate the roots of our fascination with Mars, we headed to Lowell Observatory in Flagstaff, Arizona with our colleague Kelsey Johnson. Lowell has been the site of all sorts of important discoveries about our universe, but it was originally built by another very wealthy American to observe Mars and the advanced civilization he believed could thrive there. These observations kicked off many, many imagined versions of the Red Planet and the possible futures humans might have there.

And our hosts speak with author Mary-Jane Rubenstein about how religious ideas still color the way we see the universe and Mars itself. Humans may leave Earth in numbers some day, but whatever happens, we won’t be leaving religion behind us.