SpaceX operates 2 autonomous spaceport droneships (ASDS) to land their Falcon 9 family of boosters at sea. Droneship landings are required for missions where the booster is not able to carry enough fuel to return to the launch site (RTLS) after delivering a payload into orbit. SpaceX currently has two droneships in operation, one under construction and another that was retired in 2015
Of Course I Still Love You
Of Course I Still Love You (OCISLY) is the ASDS used for landings in the Atlantic Ocean. Home-ported at Port Canaveral, Florida, OCISLY has been in service since 2015 and has been used for over 20 landing attempts.
OCISLY is supported by GO Quest, a ship retrofitted to house equipment and technicians who prepare the droneship and then secure the booster post-landing.
Status: In Service on the US East Coast.
Just Read the Instructions
Just Read the Instructions (JRTI) is the ASDS used for landings in the Pacific Ocean. JRTI is home-ported at the Port of Los Angeles, California. Just Read the Instructions was built alongside OCISLY and then towed through the Panama Canal to LA. This ASDS has been used for 7 landings, 6 of which were successful.
Status: Out of service - At Port Canaveral, Florida, preparing for service on the East Coast from 2020.
A Shortfall of Gravitas
A Shortfall of Gravitas (ASOG) is the future secondary droneship on the US East Coast. Reportedly currently under construction at an unknown location, Elon Musk estimated that ASOG will enter service in the summer of 2019
Status: Assumed to be under construction.
Just Read the Instructions (Original)
The original droneship, with the same name as the current West Coast droneship, was used for a number of experimental landing attempts throughout 2015. This droneship was replaced by Of Course I Still Love You which was built on a significantly newer barge and featured a number of upgrades.