1970

Lunar Robotic Sample Return

The Soviet Union’s robotic space exploration program in the 1960s and 1970s achieved a string of scientifically important “firsts” in missions to the Moon, Venus, and Mars. Among the most important and most technologically impressive of these were Luna 16, Luna 20, and Luna 24, the world’s first robotic sample return missions. These were small “automatic stations” that were launched from Earth on a five-day cruise to the Moon. They autonomously performed a soft landing on the lunar surface, drilled shallow holes into the surface to collect lunar samples, and then launched small sample return capsules back to Earth, where they were collected after a three-day return trip and parachute landing.

Luna 16, launched in September 1970, was the first of these autonomous sample-collection-and-return missions, returning 3.5 ounces (100 grams) of lunar soil and rock fragments from the dark lava plains of the Mare Fecunditatis impact basin. Luna 20 repeated the feat in 1972, collecting 2 ounces (55 grams) of samples from a bright highlands region also near Mare Fecunditatis, and Luna 24 did it again in 1976, returning 6 ounces (170 grams) of samples from Mare Crisium, a lava-filled impact basin near the Moon’s eastern limb. The Luna specimens complement the much larger Apollo-returned sample collection, because they include some different and unique lunar surface compositions and mineralogies. Combined, the Apollo and Luna samples provide the fundamental information that drives current theories for the origin and evolution of the Moon—including providing the key pieces of supporting evidence for the giant impact model for the formation of the Moon.

The Soviet Luna sample return missions were the most complex robotic missions yet attempted at the time. Other sample return missions have since been performed to bring back pieces of a comet tail (the Stardust mission), particles of the solar wind (the Genesis mission), and tiny fragments of a near-Earth asteroid (the Hayabusa mission). Still, the Luna sample return missions remain among the most complex planetary exploration missions ever conducted, an achievement made even more remarkable by the fact that they relied on 1960s technology. Future robotic sample return missions from other regions of the Moon, and from Mars, Venus, and near-Earth asteroids, continue to be proposed and planned.

A model of the Soviet Luna sample return lander, used for three completely robotic lunar sample return missions in 1970, 1972, and 1976.