Steven Squyres, the principal investigator for the science instruments aboard the Spirit and Opportunity Mars rovers, juggles his commitments to the four space missions he is actively involved in, as well as to his teaching and advising duties, with an energetic ease that makes some wonder if he has found the secret to a 25-hour day. Well yes, actually, he has. Not 25 hours, to be exact, but 24 hours, 39 minutes and 35 seconds, the length of one Martian day, or “sol.”