TOKEN / TAKEN A photo of the calibration target for the Mars Hand Lens Imager (MAHLI) aboard NASA’s Mars rover Curiosity, taken by that camera on Mars. The calibration target includes colour references, a metric bar graphic, a 1909 VDB Lincoln penny, and a stair-step pattern for depth calibration. The penny is a nod to geologists’ tradition of placing a coin or other object of known scale as a size reference in close-up photographs of rocks. (NASA via The Telegraph)