NASA's Curiosity rover has been investigating Mars for more than four years now. So why hasn't it even traveled 10 miles on the red planet yet?
Well, for starters, you're probably overestimating the cart's abilities. Even though it's an extremely innovative craft, its top speed isn't even a tenth of a mile per hour.
And that's in ideal, flat conditions. In reality, Mars is full of cliffs, craters and cracks. NASA notes unpredictable winds complicate things even more.
The wheels on the rover have seen some wear and tear over the years. Scientists recently noticed some new spots where the wheels are broken. But the project manager says the wheels still have enough life in them to finish the mission.
The good news is a lot of Curiosity's missions haven't required much travel.
The very first thing the rover was supposed to do was see if Mars could have ever supported life. The answer is yes, and Curiosity confirmed it years ago in an area pretty close to where it landed.
Another key mission has simply been monitoring weather patterns and radiation to see what kind of health risks future astronauts would be put through.
NASA's current goal is to have people orbiting Mars in the early 2030s. If, or when, we have astronauts walking on Mars' surface, we can bet they'll be moving a lot faster than Curiosity.
Correction: A previous version of this story said the Curiosity rover relies on solar power. The story linked the rover's short travel distance to limitations based on sunlight. The rover actually relies on radioisotope power, which doesn't require any sunlight. This story has been updated.
