In ancient times, Gale Crater rippled with the fresh, blue water of a large lake. Now it's a 90-mile-wide hole in the red Martian surface. Its water is gone, but the sediments it left behind contain clues about when and where the planet might once have been hospitable to life.
The Curiosity rover has been searching for those clues since 2012. Rambling around Gale Crater and inching up the 3-mile-high Mount Sharp at its center, Curiosity is studying the layers of rock that the lake laid down over time.
Today, a new analysis of the rover's findings reveals the red planet had the physical, chemical, and energetic ingredients to support life between 3.8 and 3.1 billion years ago. That's right around the time that life got started on Earth, and it's a larger window than scientists previously assumed.