On what date did SpaceX’s Falcon 9 first successfully land its orbital-class booster?

SpaceX’s Falcon 9 first successfully landed its orbital-class booster on December 21, 2015.

The booster was the first stage of Falcon 9 Flight 20, which launched 11 ORBCOMM-2 communications satellites from Cape Canaveral. After stage separation, the booster performed a controlled return and landed at SpaceX’s Landing Zone 1.

This achievement was important because reusable boosters can reduce launch costs and shorten the time needed to prepare rockets for later missions. Earlier Falcon 9 flights had attempted controlled landings on floating platforms, but none had achieved a successful landing before this mission.

The landing date is sometimes confused with April 8, 2016, when a Falcon 9 first landed successfully on an autonomous spaceport drone ship. The December 2015 landing occurred on land, while the later ocean landing demonstrated another recovery method.