This August, Mars Science Robot Curiosity will land on the surface of the Angry Red Planet equipped with a Penny to tell how big things are.
The camera at the end of the robotic arm on NASA's Mars rover Curiosity has its own calibration target, a smartphone-size plaque that looks like an eye chart supplemented with color chips and an attached penny.
When Curiosity lands on Mars in August, researchers will use this calibration target to test performance of the rover's Mars Hand Lens Imager, or MAHLI. MAHLI's close-up inspections of Martian rocks and soil will show details so tiny, the calibration target includes reference lines finer than a human hair. This camera is not limited to close-ups, though. It can focus on any target from about a finger's-width away to the horizon.