Construction began on Columbia in 1975 at Rockwell International’s (formerly North American Aviation/North American Rockwell) principal assembly facility in Palmdale, California, a suburb of Los Angeles. Columbia was named after the American sloop Columbia Rediviva which, from 1787 to 1793, under the command of Captain Robert Gray, explored the US Pacific Northwest and became the first American vessel to circumnavigate the globe. It is also named after the command module of Apollo 11, the first crewed landing on another celestial body. Columbia was also the female symbol of the United States. After construction, the orbiter arrived at Kennedy Space Center on March 25, 1979, to prepare for its first launch. Columbia was originally scheduled to lift off in late 1979, however the launch date was delayed by problems with both the RS-25 engine, as well as the thermal protection system (TPS). On March 19, 1981, during preparations for a ground test, workers were asphyxiated while working in Columbia’s nitrogen-purged aft engine compartment, resulting in (variously reported) two or three fatalities.