Lunar and Planetary Institute






Apollo 16 Mission


Science Experiments - Cosmic Ray Detector

The Cosmic Ray Detector measured very high energy cosmic rays from the Sun and other parts of our galaxy.

The Cosmic Ray Detector attached to a leg of the lunar module.The Cosmic Ray Detector attached to a leg of the lunar module.

The Cosmic Ray Detector Experiment was performed on Apollo 16. A reduced-scale version of this experiment was also performed on Apollo 17, when it was called the Lunar Surface Cosmic Ray Experiment. These experiments measured particles with energies of 100,000 to 150 million electron volts, much higher than measured by any other experiment during the Apollo program. The particles detected by these experiments originate both in the solar wind and from sources elsewhere in our galaxy. On Apollo 16, particles from a solar flare (an energetic eruption of material away from the surface of the Sun) were also recorded.

These experiments consisted of a set of detector plates made of various glasses and plastics, aluminum and platinum foils, and the minerals mica and feldspar. On Apollo 16, the experiment was mounted outside the lunar module prior to launch and exposed to space a few hours after launch. On Apollo 17, the experiment was carried inside the lunar module and exposed to space after landing on the Moon. On both missions, the experiment was ended during the third moonwalk, for a total detector exposure time of 167 hours on Apollo 16 and 45 hours on Apollo 17. The detector plates were returned to Earth for laboratory analysis. When cosmic ray particles penetrated the detector plates, they created microscopic tracks in the plates. The composition of each cosmic ray particle was determined from the shape of the track it left, and the particle's energy was determined from the depth to which the track penetrated.

Experiment Results (NSSDC)

Additional Instrument Details (JSC)