The Chinese rover spent a year bumping around Mars, using ground-penetrating radar to figure out what's going on below the Red Planet's current day surface.

Scientists have used orbiters and rovers to find dried streams, lakes, and gullies on Mars that hint at its watery past, but their cavalry of robots has struggled to prove the Red Planet ever had an actual ocean.

Mars once featured sun-soaked, sandy beaches with gentle, lapping waves from an ancient ocean, a new study suggests. Why it matters: The research marks the "clearest evidence yet" that the Red Planet once contained a major body of water and a more livable environment for life,