How old is Europas surface?
Possibly Europa was once the thin-ice, watery world — even teeming with life — that we imagine or wish it to be, but then it subsequently cooled and froze and has remained unchanged for eons. In this view, Europa presents a tableau of a once-fascinating world, now dormant and long dead. Can we tell if Europa is still alive? To answer this question SwRI researchers have focused on Europa’s craters, or rather its virtual lack of them. Comets and asteroids crash onto planetary surfaces, leaving impact craters. Impact craters are rare only on those few worlds (like the Earth and Io) where rapid geological forces erode, cover up, or otherwise destroy craters soon after they form. Terrestrial craters have been dated, like the 50,000-year-old Meteor Crater in Arizona and the Chicxulub Crater in the Yucatan formed by the impact that rendered dinosaurs (and most other species, too) extinct 65 million years ago. Some lunar craters were dated through analysis of Apollo moon rocks. These crater
