Mars had drier and wetter eras before drying up completely in the Hesperian period, about 3 billion years ago, according to an analysis of observational data collected by NASA’s Curiosity in the Martian Gale Crater. Mars had drier and wetter periods and dried up for good 3 billion years ago. Image credit: M. Kornmesser / ESO / N. Risinger, skysurvey.org. “A primary goal of the Curiosity mission was to study the transition between the habitable...
