On Sept. 20, 1970, the Soviet Union's Luna 16 moon probe landed on the moon to retrieve a soil sample and return it to Earth.
Luna 16 was the first robotic spacecraft to succeed in landing on the moon, scooping up a soil sample and returning it to Earth four days after its landing. Before Luna 16, the Soviet space program had tried and failed five times to return a sample from the moon. Overall, this was the third lunar sample brought to Earth.
NASA's Apollo 11 and Apollo 12 missions had also brought back some rocks and soil from the moon. Luna 16 made a soft landing on the lunar surface in a mare known as "the Sea of Fertility," where it retrieved 101 grams of lunar soil.
Why it mattered
By the time the Soviet Union launched its Luna 16 spacecraftin 1970, it had already lost the Space Race to the moon to NASA's Apollo 11, which landed astronauts on the surface on July 20, 1969, with Neil Armstrong and Buzz Aldrin collecting 47.6 pounds (21.6 kilograms) of lunar samples, including 50 moon rocks. But the Soviet Union still wanted a way to collect samples of its own.
That's where Luna 16 came in — and succeeded.
The Soviet Union launched Luna 16 atop a Proton K rocket on Sept. 12, 1970, with the probe taking eight days to reach the moon and make its historic landing. After collecting its admittedly small sample of lunar material (101 grams is only 3.5 ounces), the spacecraft loaded it into a sample return capsule and launched it back toward Earth on Sept. 21. The return capsule landed on the steppes of Kazakhstan, similar to Russia's Soyuz cosmonaut capsules today, on Sept. 24 of that year.
Luna 16 proved to the Soviet Union that it could collect moon samples robotically, without the need for costly crewed systems and their associated risk. (The Soviet Union's planned N-1 moon rocket suffered major setbacks during the race to the moon, some of them explosive.)
The mission also proved that a spacecraft could drill into the moon to collect samples, instead of just scoop up dirt or rocks on the surface. Luna 16 drilled about 35 centimeters into the moon to collect its core sample. The process took about 7 minutes and was performed entirely in the dark as the sun had set over the landing location, according to the European Space Agency. In fact, because it was night on the Sea of Fertility, Luna 16 became the first moon probe ever to land in darkness, ESA said.
