We know surprisingly little about our oceans. To help with this glaring blind spot, the XPrize has announced a new $7 million contest to foster innovations in ocean exploration technology.
It looks like it's finally going to happen, an actual mission to Jupiter's icy moon Europa — one of the the solar system's best candidates for hosting alien life.
Forget about generation ships, suspended animation, or the sudden appearance of a worm hole. The most likely way for aliens to visit us — whatever their motive — is by sending robotic probes. Here's how swarms of self-replicating spacecraft could someday rule the galaxy.