Nov 8 (Reuters) - Four astronauts who arrived at the International Space Station in April for a long-duration science mission began their return voyage to Earth on Monday as their SpaceX Crew Dragon capsule separated from the orbiting laboratory for a flight home. The Dragon vehicle, dubbed Endeavour, undocked from the space station as planned shortly after 2 p.m. Eastern time (1900 GMT) in a process carried live by a NASA webcast, with video showing the astronauts strapped into the cabin wearing their helmeted white flight suits. Operating autonomously, the spacecraft was programmed in advance to begin its departure with a 90-minute fly-around of the space station, allowing the crew to take a series of survey photographs of the orbiting outpost, circling the globe some 250 miles (400 km) high. Rocket thrusters will then fire to send the spacecraft on its final trajectory back to Earth. If all goes smoothly, Endeavour was scheduled to parachute into the Gulf of Mexico off the Florida coast at about 10:30 p.m. EST on Monday (0330 GMT Tuesday), following a total return flight time of eight hours, including a fiery re-entry through Earth"s atmosphere. Frictional heat generated as the capsule plunges through the atmosphere typically sends temperatures surrounding the outside of the vehicle soaring to 3,500 degree Fahrenheit (1,927 degrees Celsius). The capsule and crew are to be picked up at sea by a special recovery team standing by in the Gulf. The crew consists of two NASA astronauts - mission commander Shane Kimbrough, 54, and pilot Megan McArthur, 50 - along with Japanese astronaut Akihiko Hoshide, 52, and fellow mission specialist Thomas Pesquet, 43, a French engineer from the European Space Agency. They were lofted to orbit atop a SpaceX Falcon 9 rocket that lifted off April 23 from the Kennedy Space Center in Florida. They are the third crew launched into orbit under NASA"s fledgling public-private partnership with SpaceX, the rocket company formed in 2002 by billionaire entrepreneur Elon Musk, who also founded electric car maker Tesla Inc (TSLA.O). The returning team was designated "Crew 2" because it marks the second operational" space station team that NASA has launched aboard a SpaceX capsule since resuming human spaceflights from American soil last year, after a nine-year hiatus at the end of the U.S. space shuttle program in 2011. The replacement team, "Crew 3," was originally slated to fly to the space station at the end of October, but that launch has been delayed by weather problems and an unspecified medical issue involving one of the four crew members. One irregularity confronting the returning Crew 2 is a plumbing leak aboard the capsule that has put the spacecraft"s toilet out of order, meaning the astronauts will have to relieve themselves in their spacesuit undergarments if nature calls during the flight home, according to NASA.