It would have been pretty heartbreaking for space fans if Spirit and Opportunity, the twin Martian rovers, had survived on the Red Planet all these years, only to be shut down and lost for good due to budget cuts.

Apparently NASA sent a letter last week to the Jet Propulsion Laboratory, the lab that runs the rovers' program, specifying a $4 million cut. Scientists said this move would have forced them to put one rover into hibernation mode, and limit the duties of the other.

When NASA's Phoenix lander parachutes from orbit and touches down on the outskirts of Mars' northern polar ice cap on May 25, it will join the Spirit and Opportunity Mars Exploration Rovers as NASA's active roster on the planet's surface. And, as is typical of the youngest child, Phoenix will receive the majority of NASA's attention during its mission.

Day 1,464 of the Mars rovers' 90-day mission to Mars (for those of you keeping track), and Steve Squires, the head of science operations for the Spirit and Opportunity rovers is getting us up to date on their latest findings. Most important: serendipity in action. The Spirit rover's right front wheel has broken, so engineers turn the rover around, drive it in reverse, and drag the wheel behind the rover. As it slogs across the planet, it carves a trench. And my, what a trench it carves.