Eastern California's Mono Lake is where scientists conducted experiments aimed at determining whether a particular kind of salt-loving microbe could consume arsenic rather than phosphorus to keep life's machinery going. The results suggested that life is more adaptable than we thought -- and that's good news for astrobiologists looking for places where life could exist beyond Earth. Even though the microbe is totally terrestrial, Mono Lake is an alien-looking place, as my colleague Robert Hood pointed out in an earlier posting. Mono Lake also has an unusual chemistry: It ranks as one of the most arsenic-rich bodies of water on Earth (although the lake's fans emphasize that the water isn't as toxic as you might think.) It's also more than twice as salty as the ocean. The lake, which has no outlet, is thought to have existed for at least 760,000 years and possibly much longer.

This image of Mono Lake was captured in 1999 by NASA's Landsat 7 satellite, and it serves as the second offering in our Cosmic Log Space Advent Calendar. Come back every day from now until Christmas for another image of Earth as seen from space. By the time Advent is over, we'll have all 25 images stacked up right here.

You can also check out these other Advent calendars with space themes:

• The Big Picture at Boston.com: Hubble Advent calendar
• Planetary Society: Solar System Advent calendar
• Zooniverse Advent calendar

Here’s wishing you a happy holiday season, with true peace on Earth and goodwill toward all.