On re-entry Casper hit the atmosphere at an altitude of about 400,000 feet above the earth and at a velocity of nearly 25,000 miles per hour.
The LM eventually crashed due to lunar gravity anomalies. Since Houston didn’t know exactly where it landed, it was not useful to calibrate seismic experiments on the surface.
It was the only time in their whole lunar stay that Charlie had a real moment of panic and thought he had killed himself.
“There you are, our mysterious and unknown Descartes Highlands Plains. Apollo 16 is gonna change your image.” John Young