[jmcenanly]

As of April 10, the Spirit rover had covered about 7,092.29 meters (4.41 miles), after having been on Mars since January 2004. The Apollo 17 astronauts covered roughly the same distance in the course of an afternoon. Robots make great assistants, but they will not replace us.

[SunkenCiv]

However, the astronauts spent fewer hours collectively than just one of the rovers; the money involved in just one manned mission to Mars, robotic surface probes with various kinds of sensors and experiments could study the entire planet.