Megan McArthur has spent her life messing with microgravity. She was on the team that got the first commercial cargo mission to the International Space Station. She's watched her friends launch in a Soyuz rocket from Kazakhstan. And as a NASA aerospace engineer, she was the flight engineer on the space shuttle's last mission to repair the Hubble Telescope.
For Earthlings stuck here in 1G, getting to operate a robotic arm that wrangles Hubble into an airlock might seem like enough excitement for a lifetime. But earlier this month, McArthur also became the 50th person to orbit Earth---and live under the sea. The aquanaut-astronaut plunged into antigravity for the NASA Extreme Environment Mission Operations' twenty-first mission. Along with eight other crew members, she spent 16 days aboard the underwater Aquarius Reef Base, conducting research in an environment that simulates space exploration.
NEEMO is the latest in a series of NASA-operated missions designed to inform spaceflight. (Another, the Hawaii Space Exploration Analog and Simulation, finishes a year-long program this week.) “We have great simulators at NASA, and they’re really good at teaching procedures,” says Bill Todd, who has been a spaceflight trainer for NASA since 1986 and founded NEEMO in 2000. “But the reality is, when it’s over, you go home and back to your family. You’re not learning how to live for extended periods of time in an isolated extreme environment.”
McArthur was primed for extremes from a young age. Her father was a naval aviator, and she grew up on air bases all over the world---where watching air shows got her interested in space flight. Eventually, she got a degree in aerospace engineering from UCLA.
Soon after graduation, a friend of McArthur’s heard about the Biennial International Human-Powered Submarine Races, a competition to construct underwater vehicles. She was in. “When we built it, I was the only one that would fit in the pilot spot,” says McArthur. And because it's much more complicated to build a pressurized sub, the cockpit was open to the water. “I had to be on scuba in order to drive it, so I got certified.”
Previously obsessed with the wide open spaces above Earth, McArthur got sucked into the depths below. She found the Applied Ocean Science doctorate program at the University of California, San Diego, and spent her time there studying acoustic oceanography.
Between pursuing a pilot’s license on the side and deploying scientific instruments on the seafloor, her talents did not go unnoticed. “Conducting operations from a ship or underwater has some similarities to operating in space,” says McArthur. In the final year of her PhD, McArthur entered NASA's astronaut class of 2000. For sixteen years, McArthur offered operational support for spaceflight missions, until she finally got chance to participate in NEEMO.
Over the course of the two-week NEEMO mission, McArthur and crew spacewalked into the sea, collecting data on coral reefs. They spent time researching a hypothesis that telomeres, nucleotide sequences that play a role in aging, might shorten during spaceflight. And they did all this while simulating similar time delays that astronauts experience while flying to Mars—about fifteen minutes on either end. “It’s about the crew being a little bit more autonomous,” says McArthur. “You have to provide concise, clear information that describes the problem you’re having, and the ground team needs to plan differently for how they’re going to provide the answer.”
The parallels to space don't end there. One of McArthur's favorite projects on this NEEMO mission was using Minion, the first DNA sequencer to go under the sea. “I sequence DNA in the laboratory, but it was cool to be able to take that underwater and be part of the team that was the first to do that,” says Dawn Kernagis, one of McArthur’s crew members (McArthur calls her “Dawn of the Deep”). One of the pocket-sized Minions went up to the ISS earlier this summer, too---and with it now in orbit, McArthur and Kernagis are excited to compare space and sea sequencing.
The NEEMO team swabbed samples around the Aquarius habitat and processed the collection with Minion, as well as sent it back to the surface for NASA to study with a standard sequencer. That's different than the approach on the ISS---for now, sequencing is limited to preset samples launched up to the station. “The idea was that we could take environmental samples all the way through sequencing, so in the future that is something you could do in a space environment,” says McArthur. She may never make it back to space---but her work certainly will.
