"You wouldn't need a backhoe to dig up this ice. You could use a shovel," the paper's lead author, Sylvain Piqueux of NASA's Jet Propulsion Laboratory, said in a blog post. "We're continuing to collect data on buried ice on Mars, zeroing in on the best places for astronauts to land."

Locating reserves of ice is important to enable manned missions to the planet, and could help identify sites for projects like SpaceX's planned Mars base. Water is heavy to transport aboard rockets, so finding it on Mars could help humans survive there. However, because the planet has such a thin atmosphere, most water on the surface evaporates quickly.

We've known for a while that there's water on Mars in the form of ice. In 2008, NASA's Mars Phoenix lander discovered frozen water in a soil sample after landing on the planet a month earlier.

Looking below the Martian surface provides the best hope of finding accessible water ice, and that there may even be liquid water beneath the polar ice caps. With this new map, researchers have a blueprint for where to start planning missions and eventually sending astronauts to Mars.