Now only dusty riverbeds mark its surface, its air is practically a vacuum, and nearly nothing stands between Mars and a never-ending onslaught of space radiation.

MAVEN is a spacecraft on a mission to find out what happened to the red planet's lost features. In orbit since September 2014, the probe has swooped through Mars' turbulent lower atmosphere, witnessed a shimmering aurora, and braved a solar storm. The data from these adventures gives scientists a glimpse into Mars' past. In a slew of new papers published today in Science, the scientists present the mission's first findings.

Billions of years ago, Mars was a different planet, in a different solar system. The sun was hotter then, spewing radiation that scientists believe stripped away the planet's atmosphere and water.