Mars mission astronauts rehearse water landings off Texas

In this Thursday, July 13, 2017 photo, NASA astronaut Victor Glover signals back up to astronaut Daniel Burbank that he is OK after jumping into the G

In this Thursday, July 13, 2017 photo, NASA astronaut Victor Glover jumps into the Gulf of Mexico while practicing an emergency egress situation aboar

In this Thursday, July 13, 2017 photo, NASA astronaut Suni Williams, second from right, looks out over the Gulf of Mexico where testing of the Orion c

GALVESTON, Texas (AP) — NASA astronauts training for a possible mission to Mars have been practicing water maneuvers in a mock-up Orion space capsule in the Gulf of Mexico.

Several astronauts trained Thursday in the open water, about 4 miles (6.5 kilometers) from Galveston, Texas.

An Orion spacecraft is being prepared at Johnson Space Center in nearby Houston. It is intended for flight with NASA's new SLS or Space Launch System, the most powerful rocket the agency says it has ever built.

The astronauts wore bright orange training uniforms as they trained for a possible water landing, jumping into the water, using flotation devices and deploying a life raft.

Coast Guard and other NASA and military safety personnel were positioned nearby.