Due to the predicted path of Hurricane Rina, the 15th NASA Extreme Environment Mission Operations, or NEEMO, ended earlier than planned. The National Oceanic and Atmospheric Administration (NOAA) operates the Aquarius Undersea Laboratory and the agency determined Rina posed a risk to the safety of the mission taking place near Key Largo, Florida.

The six aquanauts of the NEEMO crew left the facility, where they lived for five days, and returned to the surface of the Florida Keys National Marine Sanctuary in Key Largo on Wednesday morning.

The six-member NEEMO crew - Commander and NASA astronaut Shannon Walker; Japan Aerospace Exploration Agency astronaut Takuya Onishi; Canadian Space Agency astronaut David Saint-Jacques; Steven Squyres of Cornell University; and James Talacek and Nate Bender of the University of North Carolina Wilmington - kicked off this year's mission on Oct. 20, after an initial delay caused by another storm in the area.

The NEEMO crew conducted six underwater spacewalks and one day of scientific research inside the Aquarius habitat.

They also completed four days of scientific asteroid exploration analog operations using the deep worker submersibles that stood in for the Space Exploration Vehicle.

This year's mission was the first NEEMO to focus on operational concepts that would be used in human exploration of an asteroid.

"Despite the length, we accomplished a significant amount of research," said NEEMO Project Manager Bill Todd. "We're already learning lessons from working in this environment."

The remainder of NEEMO 15 will not be rescheduled, and all media events are cancelled. The NEEMO 16 mission is tentatively set for the summer of 2012.