Mars is so far away that radio signals traveling at the speed of light take several minutes to get there from Earth. With that delay, driving a rover on Mars by remote control is quite a logistical challenge.
Each Martian drive takes hours of careful planning. Engineers scrutinize stereo images taken each day by a rover's navigation cameras and plot a route that avoids obstacles. Programmed instructions are sent to the rover, and it executes them on its own. At most, the Curiosity rover can manage about 470 feet of driving per day.
If the navigation cameras don't provide a good view, Curiosity can also drive on its own, using its cameras to detect obstacles, but that's much slower because of all the image processing that's needed.
Engineers at NASA's Jet Propulsion Laboratory are studying ways to do use a drone helicopter to scout the way forward.
Even though Martian gravity is only a third as strong as Earth's, the air is a hundred times thinner. Could a drone really fly in such thin air? So the helicopter would have to be lightweight, and its propeller blades either have to spin faster or be bigger than an Earth drone's. The engineers came up with a design that weighs a little over two pounds, with blades three and a half feet across. It could help a rover to drive three times as far in a day.
Mars exploration is getting more sophisticated all the time.
Find Out More:
"Helicopter Could Be A Scout' For Mars Rovers" (NASA Jet Propulsion Laboratory)
"Mars Science Laboratory" (NASA Jet Propulsion Laboratory)
"Martian Curiosity: How Do You Drive a $2.5 Billion Dollar Mars Rover?" (Space.com)
"Crazy Engineering: Mars Helicopter" (NASA Jet Propulsion Laboratory video)