"Our sense has been that while Mars is a lousy environment for supporting life today, long ago it might have more closely resembled Earth," said Andrew H. Knoll, also of Harvard and on the study team.

Not long ago, Castresana contacted me again, and for the first time in a while he sounded enthused.

When Thea and her husband moved to Los Angeles a few years ago, she had no friends close by and was alone frequently while her husband worked long hours.