July 15 (UPI) -- Axiom-4 astronauts returned to Earth on Tuesday following their 18-day mission aboard the International Space Station. The crew splashed down in their SpaceX Crew Dragon capsule "Grace" in the Pacific Ocean off the coast of California at 5:32 a.m. EST. Grace initially left the ISS Monday at 7:15 a.m. During their time on the ISS, the four astronauts Peggy Whitson , Shubhanshu Shukla, Slawosz Uznanski-Wisniewski and Tibor Kapu conducted more experiments and technology