|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
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.