Dick Johnson writes:

A penny in today's economy does not go very far, but that has not stopped NASA from making one 1¢ piece stretch all the way to another planet: Mars.

The copper coin is attached to a smartphone-size plaque at the end of the robotic arm on Curiosity, NASA's Mars Science Laboratory car-size rover. The plaque, which was added to the vehicle as a calibration target, looks like an eye chart supplemented with color chips and the attached penny.

Launched last November, Curiosity is scheduled to touch down on Mars this August.

Targeted for a landing inside the Red Planet's Gale Crater, Curiosity will then begin its two-year mission to determine whether the area's environment has ever been favorable to support microbial life.

Researchers will use Curiosity's calibration plaque to test one of the six-wheeled rover's five science cameras, the Mars Hand Lens Imager (MAHLI).

"When a geologist takes pictures of rock outcrops she is studying, she wants an object of [a] known scale in the photographs," said principal investigator Ken Edgett with Malin Space Science Systems in San Diego, Calif. "If it is a whole cliff face, she'll ask a person to stand in the shot. If it is a view from a meter or so away, she might use a rock hammer."

"If it is a close-up, as the MAHLI can take, she might pull something small out of her pocket. Like a penny," Edgett said.

Curiosity's 1¢ piece is not just any old penny.

Edgett picked out and purchased the penny with his own funds. A 1909 "VDB" cent, the coin is from the first year Lincoln pennies were minted, the centennial of President Abraham Lincoln's birth. The initials ("VDB") of the coin's designer - Victor David Brenner - are etched onto the coin's reverse.

"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?" Edgett said.

To read the complete article, see:Penny payload: NASA Mars rover Curiosity carries coin for camera checkup(www.collectspace.com/news/news-020712b.html)

Here's the original NASA version:Mars-Bound NASA Rover Carries Coin for Camera Checkup(www.nasa.gov/mission_pages/msl/news/msl20120207.html)