This isn’t the first time an unusual feature on Mars has sparked a frenzy. Over the years, eagle-eyed space enthusiasts have claimed to spot faces, pyramids, tunnels, and even Bigfoot lurking in ...

Unlike our lovely Earth, Mars won't shield us from blasts of cosmic radiation. If we hope to live there, we'll need to equip our future colonies with underground tunnels, Robert Zubrin ...

Those could even connect to potential tunnels underneath the surface ... so that astronauts could stop off as they head to Mars, for instance. But those long journeys will be dangerous ...