Where to hunt for life on Mars

After decades of sending missions to Mars, NASA is now zeroing in on regions of the red planet that they think have the best chance of determining whether the world has hosted — or hosts — life.

The big picture: Scientists are now able to point to parts of Mars that were once likely wet and warm, with geological signatures similar to the rivers, deltas and lakes on Earth — upping the odds that those parts of Mars could have once been friendly to life.

"Habitable and inhabited are two...