On May 7th, a new message popped up on the micro-blogging website Twitter. "Less than 20 days till I land on Mars!" it declared.

The Mars Phoenix Lander was announcing its approach to the Red Planet, and has kept up a steady stream of chatter since. It sends frequent updates about its activities, scientific objectives, and even its emotional state (channeled through a human brain at NASA's Jet Propulsion Laboratory in Pasadena).

Like Ernest Shackleton's diary of his epic trek in Antarctica, Phoenix's blog posts tell a story of exploration and adventure to the home-bound masses. It's currently the 14th most popular Twitter feed, surpassing such personalities as punk rock singer Henry Rollins and mommy-blogger Dooce. Here we give you selected quotes from Phoenix's journey from Mars orbit to the polar plain, in its own words--or "tweets."

Oh, and there could be other Martian diaries in the future. "MarsPhoenix is the first [to use Twitter]!" said Phoenix. "When I get there I'll tell the rovers to do it too :-)"