Probe for sensing contact with the lunar surface as the Lunar Module (LM) landed on the moon.

Consists of an aluminum tube with a switch at the end, and a spring-driven mechanism for rotating the probe to the extended position.

The switch would activate two blue “Lunar Contact” lights on the LM control panel, alerting the crew to shut down the descent engine to complete the landing.

The tube is covered with insulation made of gold-colored Kapton film, and black Inconel foil for the side facing the LM descent engine.

A small access port near the end of the tube allowed access to the switch. NASA photo shows the Apollo 11 LM with its landing gear and lunar surface sensing probes extended. The landing gear at the front of the LM did not have a sensing probe to prevent interference with moon-walking astronauts as they descended the ladder.

NASA photos show the +Y footpad of the Apollo 11 LM on the moon with the lunar surface sensing probe bent outward, and as the probe frames the bottom of Buzz Aldrin’s famous image. (The +Y position is to the right when facing forward in the LM.) Also see: Grumman engineering drawing for installation of sensing probe insulation: Grumman removal tag for this sensing probe: 2.52 lbs. (1.14 kg)