JACKSONVILLE, Fl. (WSAV) – Those hanging out off the coast of Jacksonville, Florida on Friday might have noticed a splash, not so much from a bottlenose dolphin, but from NASA’s SpaceX Crew-4 astronauts, who returned to Earth in a parachute-assisted splashdown after their mission to the International Space Station (ISS) and spending 170 days in orbit.

Astronauts Bob Hines, Kjell Lindgren, Jessica Watkins, Samantha Cristoforetti and the spacecraft were retrieved from the ocean by Teams aboard SpaceX recovery vessels.

NASA astronauts (L-R) Jessica Watkins, Robert Hines, Kjell Lindgren, and European Space Agency astronaut Samantha Cristoforetti inside the SpaceX Crew Dragon Freedom spacecraft onboard the SpaceX recovery ship (Photo by Bill Ingalls/NASA via Getty Images)

The international crew has spent nearly six months on the ISS conducting science.

“Their work aboard the orbiting laboratory will help prepare future explorers for future space missions,” said NASA Administrator Bill Nelson in a written statement. “Working and living on the space station is the opportunity of a lifetime, but it also requires these explorers to make sacrifices, especially time away from loved ones. Kjell, Bob, Jessica and Samantha, thank you for your contributions over the past six months to science, innovation, and discovery!”

Throughout their mission, the astronauts contributed to science such as how improvements to space diet affect immune function and the gut microbiome, explored possible adverse effects on astronaut hearing from equipment noise and microgravity and they examined a concrete alternative made with a material found in lunar and Martian dust.

International Space Station orbit the earth, computer generated image. (Getty Images)

The astronauts also investigated microgravity-induced changes in the human immune system similar to aging, tested a novel water-reclamation membrane and did a host of maintenance activities on the ISS and technology demonstrations.