Penetrometer

The Self-Recording Penetrometer was a device used on Apollo 15 and 16 to measure some mechanical properties of the lunar soil. When an astronaut pushed on the upper end, the bearing plate or lower cone and shaft would penetrate into the lunar soil while the reference pad stayed on the surface. A retractor cable mechanism running from the reference pad to the upper housing actuated a stylus which would move axially along the recording drum to measure the depth of penetration. The force applied through the extension handle by the astronaut was measured by a coil spring which caused the recording drum to rotate under the stylus by an amount proportional to the force.