It's one of the great, unsolved mysteries of space: what happened to the water that used to cover the surface of Mars?
If NASA's Maven spacecraft succeeds, we may finally learn the answer . The probe arrived in Mars orbit this week after traveling some 442 million miles over ten months. Previous missions to the red planet have searched for lost water below the surface. But Maven will look for signs that Mars's water went skyward, stripped away by the solar winds that have battered the planet for billions of years.
And since Mars comes the closest in our solar system to resembling our own planet, Maven's findings could help tell us what Earth's future may hold.
Tim De Chant is the the senior digital editor at NOVA here at WGBH and the editor of the NOVA Next blog.
