An autonomous spaceport drone ship (ASDS) is an ocean-going vessel derived from a deck barge, outfitted with station-keeping engines and a large landing platform. Construction of such ships was commissioned by aerospace company SpaceX to allow for recovery of rocket first-stages at sea for high-velocity missions which do not carry enough fuel to return to the launch site after lofting spacecraft onto an orbital trajectory.
SpaceX has two operational drone ships: Just Read the Instructions in the Pacific for launches from Vandenberg, and Of Course I Still Love You in the Atlantic for launches from Cape Canaveral. As of 25 June 2017, thirteen Falcon 9 flights have attempted to land on a drone ship, with eight of them succeeding, the first successful attempt being the CRS-8 mission in April 2016.
The ASDS ships are a key component of the SpaceX reusable launch system development program which aims to significantly lower the price of space launch services through “full and rapid reusability.” Any flights going to geostationary orbit or exceeding escape velocity will require landing at sea, encompassing about half of SpaceX missions.
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