4 years on Mars: Rovers Continue to Amaze — Space.com

The Mars rovers Spirit and Opportunity were given 90 days to get their science done, but four years later, the rovers are still roving.

Since the rovers bounced onto Mars’ surface, they have collectively driven more than 11.8 miles (19.1 kilometers) and snapped more than 210,000 images. That’s roughly 55 standard DVD movies worth of uncompressed data.

Scientists have used this information through the years to crank out more than 100 studies about the planet’s geologic past “with many more in progress,” Lemmon said.

“It’s been a great year for the rovers and we’re getting deeper into Martian history than we’ve been done before,” Lemmon said. “These robots have entirely changed the way we view Mars.”

I have no idea how a hopeful 90-day mission turned into a still-going four-year mission; it seems like a pretty wide gap of prediction on the part of NASA. Regardless, it is always good to see space missions that go better than expected.