A team of astronauts and divers is wrapping up a record-setting mission to the ocean floor that featured undersea moonwalks and robotic surgeries remotely controlled by a doctor in Canada.

The six-aquanaut crew of the NASA Extreme Environment Mission Operations (NEEMO) 9 program returned to the Earth’s surface April 20 after 18 days of underwater living aboard Aquarius, an undersea laboratory stationed 20 meters below the surface off Key Largo in the Florida Keys.

“Every single thing that we’re doing on this mission directly relates to exploration,” NASA astronaut and NEEMO 9 aquanaut Ron Garan said during a phone call to Aquarius. “One of the big things we’re trying to look at is to see how we can have collaborative effort between the human astronauts and robotic explorers.”

NEEMO 9 is the longest NASA ocean-floor mission and the longest to date aboard Aquarius. Garan has been working aboard the aquatic laboratory with fellow NASA astronaut Nicole Stott, NEEMO 9 commander Dave Williams — of the Canadian Space Agency — and University of Cincinnati physician Tim Broderick since diving down to the undersea outpost April 3. Professional Aquarius divers Jim Buckley and Ross Hein also are aboard the laboratory.

“Except for the launch, we’re basically on a space mission,” Garan said, adding the mission is supporting NASA’s plan to return astronauts to the Moon by 2020. “We’re in an extremely hazardous environment … it’s a small confined space with the crew on a very tight timeline.”

Aquarius is operated by the National Undersea Research Center at the University of North Carolina at Wilmington for the National Oceanic and Atmospheric Administration (NOAA). NOAA owns the ocean-floor laboratory, which has as much living area as NASA’s Destiny lab module aboard the international space station (ISS).

One of the key goals for the NEEMO 9 crew included the assembly and operation of a surgical robot designed to allow physicians to dress wounds remotely with only an Internet link-up between them.

Canadian doctor Mehran Anvari, a veteran of telemedicine experiments with past NEEMO crews, directed the robot to suture a gash inside Aquarius. But instead of working aboard Aquarius — or even aboard a surface ship — Anvari sat at a workstation in the Canadian city of Hamilton, Ontario, where he directs the Center for Minimal Access Surgery at McMaster University.

“It was fantastic,” said Anvari of the robot’s performance, adding that he also mentored the NEEMO 9 crew in medical procedures. “Last [mission], we had very simple robotics and our traditional surgical robots could not fit inside the habitat.”

But for NEEMO 9, the aquanauts constructed a small, portable robot equipped with cameras and dexterous pincers to manipulate rock samples and suture needles.

A two-second time delay — similar to that experienced in Earth-Moon communications during NASA’s Apollo missions — also was built into the system to simulate a lunar manned mission.

“This also has connotations for people on Earth,” Anvari said of the telerobotic surgery. “A two-second time delay is something that you’d experience if you have more than one satellite hop for your communications to a remote area on Earth.”

Anvari also used the robot surgeon to transfer ocean floor rock samples collected by Scuttle — a wheeled rover designed to test lunar robotic exploration techniques — into a storage compartment.

Mary Sue Bell, a planetary geologist at NASA’s Johnson Space Center in Houston, watched over the procedure, which she said reduces the risk of contamination from human handlers.

“Even [astronaut] gloves can present a contamination risk,” Bell said.

NEEMO 9 aquanauts did not leave all of the work in robot hands during their mission.

The crew also toiled alongside Scuttle to assemble underwater structures while wearing a special backpack to simulate the gravitational tug of the Moon.

“We’ve weighed them out to the same gravity they’d experience on the Moon, one-sixth Earth’s gravity,” Garan said of the aquanaut ‘moonwalkers.’ “They assembled what is essentially a communications relay station.”

The six-meter structure is similar to one that future astronauts might have to build on the Moon in order to stay in contact with a lunar base camp on extended moonwalks, the aquanauts said.

“The lunar horizon is only about 1.5 miles (2.5 kilometers), and if they go beyond that we’re going to need to communicate,” Garan added. “This structure would allow us to extend our communications range out to 5.9 miles (9.5 kilometers).”

Garan said all of the lessons learned from NEEMO 9 and future Aquarius expeditions will be pooled alongside NASA’s Apollo experiences in a comprehensive database to support the U.S. space agency’s human space exploration efforts.

NASA has used the Aquarius laboratory as a training ground for space station crewmembers, including astronaut Jeffrey Williams, who served aboard NEEMO 3 in 2002 and called the underwater outpost from the ISS during the most recent expedition. He currently serves as Expedition 13 flight engineer.

“One thing that we don’t have here that you guys have down there are all those little critters outside,” Williams told the NEEMO 9 crew from orbit, adding that his first few days aboard the ISS were exhausting. “I remember on Aquarius, just sleeping very well. That was some of the best sleep I’ve ever had.”

Much of the support for the NEEMO 9 crew — which includes wireless communications from the ocean floor, as well as high-speed connections for video, data and Internet access — has been due to a five-year effort to turn Aquarius from a coral reef camp into a robust undersea laboratory.

“In the course of these missions we’ve increased the bandwidth by 10 times for our real-time data communications from the sea floor,” said Andy Shepard, NOAA’s Undersea Research Center director for Aquarius. “It was the big leap forward that we needed to really make the lab what we needed.”

About $500,000 in NASA support over the last five years has allowed Aquarius — the last of NOAA’s saturation-diving platforms — to reach its current state. The agency is now working with NASA and the U.S. Navy to develop a mobile saturation-diving platform that could aid in submarine rescues and marine studies.

“We’re now looking for a suitable chamber that would be cost-effective,” Shepard said, adding that the chamber would initially be used as an Aquarius extension. “We’d start off by doubling the living area of Aquarius. It’s one of the more comfortable habitats … but we can use some more space.”

Comments: tmalik@space.com