NASA’s Insight lander is expected to set down along the sunny equator of Mars in late November. Its mission: Study Mars’s ancient interior, a task that might shed some light on our own planet. That’s because the same plate tectonics that give Earth its mountain ranges—and the conditions for life itself—have over eons transformed our ancient geology. Mars, on the other hand, has had a comparatively uneventful past three billion years, likely because it’s too small to produce the energy for history-erasing tectonic shifts. So it might still hold clues to how rocky worlds, like ours, first formed and evolved.