What Life on Mars Could Mean

I am optimistic that some time in the coming 30 years we will discover strong evidence that life once existed on Mars, or even exists now.  If you ask Gilbert Levin, he'll tell you we already have that evidence from the Viking lander's Labeled Release experiment.

This is nothing new to those who follow the discussion on Mars life,  but if we do find Martian life, past or present, it could have any of four possible implications for the origin of life, in ascending order of fascination:

1. Life originated on Earth and migrated to Mars on Meteorites.
2. Life originated on Mars, and migrated to Earth on Meteorites
3. Life originated somewhere else (probably Venus), and migrated to both Earth and Mars.
4. Life originated independently on both Earth and Mars.

Number 4 is by far the most interesting of the four possibilities.  It implies that the origin of life is not a rare event.

If not Mars, then we hope to reach this conclusion by studying Enceladus, Titan or Europa.  The odds of cross-contamination there are much reduced.  Is it possible, that whenever you have a sufficiently diverse mix of ingredients in sufficient amounts, and a stable flux of energy through a system for a long time, that the chemistry progressively gets more complex and eventually some of it becomes self replicating?

If so, then probably then entire universe is teeming with life, and some of it is looking at us and wondering; who's there?