Earth's oldest biosphere still draws interest

What does Dale Andersen, a senior scientist at the Carl Sagan Center within the SETI Institute whose research concentrates on microbial environments of the Artic, Antarctic, Abacama Desert, Death Valley and Siberia, have in common with Zena Cardman, who grew up in Williamsburg and is a Bruton High grad, selected as an U.S. astronaut candidate?

It turns out, quite a lot.

Andersen wrote to me: "You may have heard that NASA selected their most recent class of astronaut candidates and Zena Cardman is among those selected. She is a friend of mine and my family. I first met her at Pavilion Lake in British Columbia in 2008 when she joined us as an undergrad. We worked there...