Apollo 11 first deployed a scientific experiment package on the Moon’s surface.
After landing in July 1969, Neil Armstrong and Buzz Aldrin set up the Early Apollo Scientific Experiment Package, or EASEP, near the lunar module. It included instruments such as a passive seismometer, a laser-ranging retroreflector, and a solar-wind experiment.
These devices extended Apollo 11 beyond a symbolic visit by producing measurements after the astronauts departed. The seismometer detected lunar seismic activity, while the retroreflector allowed scientists on Earth to measure the Moon’s distance with high precision using laser pulses.
Apollo 12 and later missions deployed more extensive Apollo Lunar Surface Experiment Packages, known as ALSEP. EASEP was the lighter, rapidly deployable version used on the first landing because the crew had limited surface time.