What was the name of the solar wind experiment deployed by Apollo 11?

The solar wind experiment deployed by Apollo 11 was the Solar Wind Composition Experiment. It used a sheet of ultra-pure aluminum foil mounted on a telescoping pole and exposed it to the Sun on the lunar surface.

The experiment was designed to capture particles in the solar wind—streams of charged material flowing outward from the Sun—without interference from Earth's atmosphere or magnetosphere. Apollo 11 astronauts exposed the foil for 77 minutes before sealing it for return to Earth.

A Swiss team led by Johannes Geiss and colleagues at the University of Bern helped design the experiment. Laboratory analysis measured isotopes of helium, neon, and argon, providing some of the first definitive measurements of solar material.

The experiment is often confused with Apollo 11's Laser Ranging Retroreflector, which remains on the Moon and is used to measure the Earth-Moon distance. The Solar Wind Composition Experiment was instead a sample-collection device, and versions also flew on Apollo 12, 14, 15, and 16.