Apollo 11 carried the first scientific experiment package left on the Moon by astronauts in July 1969.
Neil Armstrong and Buzz Aldrin deployed the Early Apollo Scientific Experiment Package at Tranquility Base. It included a passive seismic experiment, a laser-ranging retroreflector, and a passive seismometer designed to detect lunar vibrations and impacts.
The laser retroreflector remained useful long after the mission because observatories could bounce laser pulses off it to measure the Moon’s distance from Earth with great precision. Apollo 11’s seismometer operated for about three weeks before its power supply was switched off.
Apollo 12 and later missions delivered more extensive Apollo Lunar Surface Experiment Packages. Apollo 11’s instruments were limited by the short surface stay, but they marked the beginning of continuous scientific measurements from the lunar surface.