HOUSTON, Jan. 15 -- A SpaceX Dragon spacecraft carrying four astronauts from the International Space Station (ISS) splashed down in the Pacific Ocean off the San Diego coast in the early hours of Thursday, marking the conclusion of NASA's early-return mission for Crew-11.

The American space agency noted that splash-down at 3:41 AM brings an end to 167-day long stay of the four persons -- NASA astronauts Zena Cardman and Mike Fincke, the commander and pilot, as well as mission specialists Kimiya Yui, of the Japan Aerospace Exploration Agency, and Russian cosmonaut Oleg Platonov.

"The mission returned to Earth earlier than originally planned as teams monitored a medical concern with a crew member living and working aboard the orbital labora...