PHOTOS: Alien Robots That Left Their Mark on Mars
The truth is, Mars is a mysterious little world. We've been sending robot explorers there for decades, but there's a lot about it which is still a little puzzling. That said, we understand a lot more about our planetary neighbor now than ever before, and some things about it are, frankly, quite familiar.
As it happens, Mars is familiar enough that some astrobiologists are confident that if we can find life anywhere else in our solar system, we might find it there. After all, it's not all that much colder than Earth, and has none of the searing heat and acid skies found on certain other nearby planets.
If Mars is hiding warmer temperatures and liquid water below its surface, it's just possible that some kind of Martian life might be hiding underground even today. While there's no way of saying for certain, it's an intriguing possibility.
Image: Artists impression of ancient Mars, showing oceans of liquid water. Credit: lttiz/Wikimedia Commons.