[xoxoxoBruce]

Ken Edgett bought the special penny that's aboard Curiosity with funds from his own pocket. It is a 1909 "VDB" cent from the first year Lincoln pennies were minted, the centennial of Abraham Lincoln's birth, with the VDB initials of the coin's designer—Victor David Brenner—on the reverse. The penny is on the MAHLI calibration target as a tip of the hat to geologists's informal practice of placing a coin or other object of known scale in their photographs. "Everyone in the United States can recognize the penny and immediately know how big it is, and can compare that with the rover hardware and Mars materials in the same image," Edgett said. "The public can watch for changes in the penny over the long term on Mars. Will it change color? Will it corrode? Will it get pitted by windblown sand?" At right, the same penny, re-photographed on December 2, 2017, or Sol 1892, showing almost no visible wear, with only a small coating of dust. #

Sols = days, on Mars.