The San Diego-based Navy hospital ship USNS Mercy is scheduled to deploy Tuesday for a four-month humanitarian mission to four Asian nations, reports San Diego 10News. Converted from an oil tanker in the mid 1980s, the Mercy first saw duty in the Persian Gulf War. Following that deployment, it left its berth at Naval Base San Diego. However, the 2004 tsunami that struck Indonesia prompted the hospital ship to return to the area every year since. The Mercy carries about 400 Naval medical personnel, along with civilian crew members with the Maritime Sealift Command. Crew members on the Mercy will provide medical, dental and veterinary care in the host nations and help with civil engineering projects.