The day is finally here! In only five and a half hours, at 00:45 on March 18 (according to the spacecraft's clock), MESSENGER must ignite its main engine and run though a third of its fuel in only 15 minutes in order to enter its planned orbit around Mercury.
I've got another 365 Days of Astronomy podcast airing today, this one an overview of the MESSENGER mission with particular attention to what's been learned in the three Mercury flybys, and what's going to happen when it enters orbit only a little more than three days from now!
Space probes grant us perspective, the ability to see our place within the vastness of the solar system. But opportunities to see all of the solar system's planets in one observation are rare. In fact, there's only been one opportunity on one mission to see the whole solar system at once, until now.
Time to open the second door in the advent calendar. Until the New Year, I'll be opening a door onto a different landscape from somewhere in the solar system. Can you guess where this crater-scarred surface lies?