Apollo 16 astronaut Charlie Duke is a long way from his hometown of Lancaster, South Carolina. Even though that is Stone Mountain in the background, he's not in Georgia either. I have painted him giving a maximum push to his self-recording penetrometer. In fact, in doing so, he is leaning precariously to his left. More about this later.

The penetrometer consists of a metal shaft with a precisely designed cone and movable reference plate on one end and a recording drum on the other. As Charlie pushes in on the drum end, the cone and shaft penetrate the lunar soil, recording the force and the depth. The recorder will be brought back to Earth to better understand the mechanical properties of the lunar soil.

Mechanical properties, a most important one being bearing strength, are studied for both engineering and scientific reasons. Future design of spacecraft, surface vehicles and habitats will be based, in part, on these properties of the lunar soil.

Charlie would later say, "The penetrometer worked as advertised, but I couldn't apply a steady force. I'd start leaning on it and lose my balance. I tried two or three little techniques, and every time it worked the same way."

But Charlie's maximum push is not without complications. He will shortly lose his balance and fall to the lunar surface. But not to worry! Except for getting a little dusty, Charlie will be able to do a simple push up to his knees, then a quick knee hop back to his feet.