Answer: Camera Calibration

Among all the high-tech and thoroughly modern paraphernalia covering Curiosity Rover, there is a distinctly vintage accessory. Attached to the deck of the rover is one shiny 1909 Lincoln penny.

What purpose does a penny epoxied to the Rover serve? The presence of the penny is part nod to tradition and part practical use. Geologists traditionally include coins, often pennies, in photographs to show the scale of the samples they are photographing–in that same vein the Lincoln penny aboard the craft can be used for scale reference when presenting photos from the rover to the public.

In addition to providing a sense of scale the penny also serves a more important function as a camera calibration target for the Rover’s Mars Hand Lens Imager camera array (along side other calibration targets including a color reference chart, metric bar graph, and stair-step patterns).