Autonomous spaceport drone ship

An autonomous spaceport drone ship (ASDS) is a modified ocean-going barge developed by SpaceX and equipped with propulsion systems to maintain precise position and a large landing platform. They were developed to recover the first stage (also called the booster) of its launch vehicles. By recovering and reusing these boosters, SpaceX has significantly reduced the cost of space launch.

SpaceX operates three ASDS: Just Read the Instructions (II) (JRTI), A Shortfall of Gravitas (ASOG), and Of Course I Still Love You (OCISLY). JRTI and ASOG operate from Port Canaveral supporting launches from Kennedy Space Center and Cape Canaveral Space Force Station landing in the Atlantic Ocean, while OCISLY operates from the Port of Long Beach supporting launches from Vandenberg Space Force Base landing in the Pacific Ocean.

Depending on mission requirements, SpaceX can return the booster to the launch site for a ground landing, land the booster at sea on an ASDS, or discard it. While a ground landing is the least expensive option, it requires the most fuel and thus reduces payload capacity. Sea landings offer a balance of cost and performance, making them the most common choice, used on approximately three-quarters of missions.

In 2009, SpaceX CEO Elon Musk articulated ambitions for "creating a paradigm shift in the traditional approach for reusing rocket hardware". In October 2014, SpaceX announced that they had contracted with a Louisiana shipyard to build a floating landing platform for reusable orbital launch vehicles. Early information indicated that the platform would carry an approximately 90 m × 50 m (300 ft × 160 ft) landing pad and would be capable of precision positioning so that the platform could hold its position for launch vehicle landing. On 22 November 2014, Musk released a photograph of the "autonomous spaceport drone ship" along with additional details of its construction and size.

As of December 2014, the first drone ship used, the McDonough Marine Service's Marmac 300 barge, was based in Jacksonville, Florida, at the northern tip of the JAXPORT Cruise Terminal, where SpaceX built a stand to secure the Falcon stage during post-landing operations. The stand consisted of four 6,800 kg (15,000 lb), 270 cm (110 in) tall and 244.5 cm (96.3 in) wide pedestal structures bolted to a concrete base. A mobile crane would have lifted the stage from the ship and placed it on the stand. Tasks such as removing or folding back the landing legs prior to placing the stage in a horizontal position for trucking would have been undertaken while the booster was on the stand.

The ASDS landing location for the first landing test was in the Atlantic approximately 320 km (200 mi) northeast of the launch location at Cape Canaveral, and 266 km (165 mi) southeast of Charleston, South Carolina.

On 23 January 2015, during repairs to the ship following the unsuccessful first test, Musk announced that the ship was to be named Just Read the Instructions, with a sister ship planned for West Coast launches to be named Of Course I Still Love You (OCISLY). On 29 January 2015, SpaceX released a manipulated photo of the ship with the name illustrating how it would look once painted.

The first Just Read the Instructions was retired in May 2015 after approximately six months of service in the Atlantic Ocean, and its duties were assumed by Of Course I Still Love You. The former ASDS was modified by removing the wing extensions that had extended the barge surface and the equipment (thrusters, cameras, and communications gear) that had been added to refit it as an ASDS; these items were saved for future reuse.