Troubles parallel ambitions in NASA Mars project

NASA's new Mars rover aims high. It's bigger, more powerful and more sophisticated than any other robotic vehicle that has landed on another planet. It will try to answer a big question: Has life existed elsewhere in the solar system?

Its very ambition has gotten the rover in trouble. Thanks to a mix of technological setbacks and engineering misjudgments, the rover's epic scale is matched by epic problems. Its story offers a cautionary tale as NASA plans to devote large chunks of its science budget in coming years to grand "flagship" missions, including a spacecraft to return Mars rocks to Earth and another that would visit a moon of Jupiter or Saturn.

The new rover, known as the Mars Science Laboratory, is $235 million, or 24%, over budget. Work on it has run so late that engineers are racing to prepare the rover for its blastoff in ...