"Curiosity" is five times as heavy as the Mars Exploration Rovers "Spirit" or "Opportunity" and carries more than ten times their mass of scientific instruments . It was launched by an Atlas V 541 rocket. "Curiosity" will be expected to work for at least 1 Martian year (668 Martian sols/686 Earth days), but may live a lot longer than that. It will explore Mars with greater range than any other rover.