Extra Vehicular Activities (EVAs) would be difficult without prior training on scuba.

E GLANCES DOWN AT HIS SUIT ONE LAST TIME. He takes a deep breath, then signals "OK". His buddy, just as eager, signals back "OK". Together,they glide into the deep black ocean.
Deep black? Yes, because Earth?s blue seas are 220 miles beneath the feet of these divers. These two are astronauts, and they have practised this spacewalk repeatedly prior to their Space Shuttle mission.
Where do NASA astronauts rehearse their extravehicular activities (EVAs)? How do they train for their spacewalks? How does scuba diving help astronauts in space?

A run at the Nibble
Among the various facilities for training astronauts at NASA's Johnson Space Centre in Houston, Texas, is the Neutral Buoyancy Laboratory (NBL). It's a 62m by 31m pool, 12m deep and with half its depth 6m above ground level.
The NBL, known to astronauts as the Nibble, holds 23.5 million litres of water, kept at 28-31?C for the comfort of the support divers.

Under water at the Neutral Buoyancy Lab, known as the Nibble.

Two overhead bridge cranes and four jib cranes are used to configure underwater mock-ups of the Space Shuttle and International Space Station (ISS), including full-scale working models of their robotic arms. The jib cranes also lift the suited astronauts in and out of the tank. There is a scuba run, occasionally two, almost every working day.
The Nibble's mission is to help NASA team-members develop space-flight procedures, verify hardware compatibility, train EVA astronauts and refine EVA procedures during flight. Without such training, ISS assembly and in-orbit maintenance tasks such as the high-profile repair of the Hubble Space Telescope could not easily be performed.
On a training run, the astronauts are in communication with topside trainers, facility test co-ordinators, the flight-control team in the Mission Control Centre, and the rest of the Shuttle crew at the on-site Shuttle Mission Simulator.
Those topside watch proceedings on closed-circuit TV, and a small medical team and hyperbaric chamber stand by.

A mock-up of Space Station truss segments in the Nibble allows spacewalkers to practise maintenance and repair tasks.

Most EVAs in the Nibble these days are geared toward external work on the Space Station.
The astronauts wear training versions of the Extravehicular Mobility Unit (EMU) spacesuit, with nitrox and cooling water fed in through umbilicals. In space, the suits are self-contained.
Spacewalks last 7-8 hours on average. EVAs are rehearsed continually, from one to four years before a space flight.
Piers Sellers, one of three British-born astronauts currently working at NASA, describes the training experience: 'They get you all in spacesuits, and they overpressurise them when they put you in the water so it's 4.3psi (0.3 bar). That's the equivalent of what you have in orbit; your suit is always at 4.3psi.
'The pressure differential is the same between the inside and the outside of the suit, so the resistance of the suit to your movements is about the same.
'When you get into a suit and pressurise it, it's a bit like being in a balloon,' says Sellers.
'For example, when you want to make a fist with your hand, there's a tendency for the glove to want to pop out to its original shape. Same with the arms. You're always working against the suit, in some sense, in the tank.
'It's not a perfect analogue for spacewalking because you can never get totally neutrally weighted out, but it's pretty good. We've found it to be a very effective tool for getting a group trained.'
Scuba may provide a reasonable analogue to spacewalking, but there are important differences.
'When you plan a dive, your planning concern goes into the coming-back-to-the-surface part,' explains Piers Sellers. 'You don't want to get bent, so you plan your return to the surface carefully.
'With space, it's the exact opposite. Your chances of getting bent are when you go from the station into space. So it's at the beginning of the [EVA] activity that you have to be careful.
'We do things like breathe pure oxygen for a while. We exercise on stationary bikes for a while, to try to flush all the nitrogen out of our blood before we get into the suits, and take various precautions like that.'
'The big difference between scuba and EVA is, of course, when you go into orbit - the view!' says Sellers, a skywalker gleam in his eye.
'When you open the hatch and fall out, it's absolutely mind-shattering. This huge blue planet, and you're rolling around with this big station hanging above you, and you crawl out and everything's just glowing, because the sunlight is so strong. It's just beautiful.'

Finding NEEMO
When I visited the Nibble late last year, two teams of astronauts were conducting tests. In one half of the tank, Peggy Whitson and Dan Tani were working out the nuances of the second spacewalk scheduled for ISS Expedition 16, an upcoming long-duration flight and the first Space Station mission to be commanded by a woman, Whitson. British-American astronaut Mike Foale was acting as topside console communicator.

Ready for immersion at the Nibble.

Astronauts carry out technical assignments whenever they're not training for space missions. Foale, in part due to his long-duration mission on the Russian space station Mir in 1997, once ran the Astronaut Office's Expedition Corps. His job included providing insights for the methods the space agency would use to train astronauts
for long-duration ISS expeditions.
'We were working out the details for expedition-training four or five years ago,' says Foale. 'I had a dive in Florida to the Aquarius lab. This was before there was such a thing as NEEMO. At the time, they were setting it up.'
The deep-sea diving programme NASA Extreme Environment Mission Operations (NEEMO) is based out of Aquarius, a habitat located 3.5 miles off Key Largo, Florida, in 19m of water (hatch depth 14m). Providing around 37sq m of living and working space, this is the world's only permanent undersea laboratory.
'After visiting Aquarius, I thought that a mission in it, with a commander and two people and not too much supervision by the surface mission control, would be a good analogue for a spaceflight,' reveals Foale. 'That has been borne out.'

Nick Patrick and colleagues during his NEEMO experience in the Aquarius habitat.

A NEEMO mission, typically lasting 10 days with a crew of six, features science experiments and construction EVAs - similar to a Shuttle flight or a condensed version of an ISS 'increment'.
Twelve have been conducted, usually two or three a year, with more anticipated. Some unflown astronauts have started in Aquarius and gone on to fly missions on the Shuttle or ISS. Others have gone from astronaut to aquanaut (technically, an individual who has lived under water for 24 hours or more).
In Houston, I attended the pre-flight crew news conference for Space Shuttle mission STS-116. The crew of seven included two aquanauts: British astronaut Nicholas Patrick, a NEEMO 6 veteran preparing for his first Shuttle flight; and US Navy diver-pilot Sunita Williams, a NEEMO 2 crew-member (along with Tani) who would remain on the ISS for parts of Expeditions 14 and 15 after the Shuttle departed.
'Scuba diving is one of the things that brings you closest to spaceflight here on Earth,' said Patrick, a Rescue Diver. 'You can adopt any orientation, and things are difficult to do while you're floating. It's quite like working in space, and I'll tell you more when I get back, when I've had that experience too!
'You're working in an environment where things can go quite wrong. You have to be prepared for all sorts of emergencies - or 'contingencies', as we say here at NASA. Your safety is really in your own hands, so scuba diving is a wonderful preparation for spaceflight.'
Suni Williams agreed: 'My scuba-diving training in the past prepared me well for the whole idea of space, especially for contingencies. Nick and I have both lived in Aquarius, and we got to see how beautiful the Earth is under water. I have a feeling that looking out the window at our beautiful planet will be equally wonderful.'

Working in the pool, where the water is kept nice and warm for the support divers.

The future of EVA
I was on holiday in Houston last year when NASA authorised the controversial fifth Shuttle mission to repair the ageing Hubble Space Telescope.
That flight had been cancelled after the Columbia Shuttle disaster in 2003,
as damage to a Shuttle on launch could well prevent its safe re-entry to Earth, effectively stranding its crew in space.
However, the EVAs on the Shuttle programme's two return-to-flight test missions, STS-114 and STS-121, helped NASA reassess the Hubble decision.
Sellers, a spacewalker on 121, accomplished EVA tasks such as riding around on a 15m boom extension to the Shuttle's robotic arm to simulate repair manoeuvres, and repairing broken-wing samples with a sort of black putty.

'This huge blue planet, and you?re rolling around with this big station hanging above you.'

'So there was now proof as a result of 121 that, a) you can get to any part of the Shuttle using the arm plus the boom and stand on it and use it as a repair site and, b) you can do a limited repair, with material,' says Sellers. 'And that played into the decision to go ahead with the Hubble mission.'
But this orbiting telescope will never be triumphantly repaired again without many hours of EVA choreography and rehearsal on the ground. Scuba diving will again play a leading role in that adventure. In the third spacewalk of Michael Foale's career, during STS-103 in 1999, he and his EVA buddy replaced Hubble's main computer and Fine Guidance Sensor.
On his current assignment topside at the NBL, Foale has a front-row seat for observing the Hubble EVA runs. 'The crew has started training,' he reports cheerfully. 'The Hubble mock-up is already at the Nibble. I'm looking at the current Hubble crew and their mission with joy, fondness, envy and nostalgia.'
How does diving help us in space? Williams summarises it best: 'Scuba is instrumental in everything we do as astronauts.'

Dr C Michael Foale, CBE
Born: Louth, Lincolnshire.
Occupation: NASA astronaut since 1987.
Space flights: Four Space Shuttle missions 1992-1999 with two EVAs. Two ISS missions: Mir 23-24 with one Russian EVA (1997) and ISS Expedition 8 with one Russian EVA (2003-2004). Holds the US record for cumulative time spent in space of more than 374 days.

MICHAEL FOALE BECAME A BSAC 3rd Class Diver at 16 with RAF Luqa Diving Club in Malta, where his father was station commander. He joined the Cambridge University Underwater Exploration Group (CUUEG) in 1978 and became an Instructor two years later. 'We did the pool work at university, and then I took the students to Cornwall for seawater diving.
We also went to a gravel pit for night dives.'
As a postgraduate, Foale helped to organise scientific diving projects, partly to help assemble a NASA-worthy CV. In 1980 he led a CUUEG expedition to Plitra, Greece in search of sunken ruins, and the following year, while writing his doctorate thesis on experimental physics, helped in the excavation and raising of the Mary Rose in Portsmouth.
'I got a large number of dives there,' he says. 'Our schedule was two weeks on, two weeks off, due to the strong spring tides. We were doing two dives a day.'
In 1982 Foale, a dual British-American citizen by birth, relocated to Houston. 'My first recreational dives were in the Gulf of Mexico. My friend and I would take his 24ft boat to the Stetson Bank, 17 miles out. We would find the reefs by LORAN (long-range navigation) from the shore. He wanted to use as little gas as possible, so we would go sailing under the stars. Often we would pass by unused oil rigs.
We would tie off on a rig, and dive down it together.
The water was incredibly clear, but cold.'
A month after NASA selected him as an astronaut, Foale got married in Aruba - and got some wreck-diving in. His logbook covers Cozumel in Mexico, the Cayman Islands and Australia, from the Barrier Reef to Fitzroy, Green and Rottnest Islands.
Dive holidays with his wife Rhonda in the early '90s were sandwiched between Space Shuttle flights 'when Jenna was tiny and Ian not yet born.'
Foale experienced a unique sort of diving in 1997. He and two cosmonauts were aboard Mir when an unmanned Progress resupply spacecraft collided with the Russian space station, causing Mir to depressurise. The crew sealed off the damaged module, but for two months contended with a 40% reduction in solar power supply.
As ventilation was one of many non-critical systems, Foale's chore two hours each day was to mop up water condensate from the cold metal surfaces inside each unlit Mir module.
'It was like cave-diving, going into a dark module with a full-length suit on,' he would later explain.
Foale holds a CMAS Scientific Diver card but says: 'I've had no recreational dives lately, so I haven't been among any pretty fishes.' If he could dive anywhere on Earth, where would it be? 'Antarctica, to see penguins and seals under water, by ice shelves and bergs. I feel it's a frontier. A very beautiful, threatened environment that enlivens the explorer in me.'

Dr Piers J Sellers
Born: Crowborough, Sussex.
Occupation: NASA astronaut since 1996.
Space flights: Two Space Shuttle missions, 2002 and 2006, three EVAs on each. Temporarily held the US record for most hours of spacewalking on the International Space Station.

WHILE WORKING ON HIS DOCTORATE IN BIOMETEOROLOGY, Piers Sellers became a BSAC Class 3 diver as part of Leeds University Union SAC. 'I was a charter member, and ended up as equipment officer. I tried to keep all the stuff running.
'We spent the autumn term doing all the pool work, then we went to Lake Windermere, smashed holes in the ice, and did our open-water snorkel stuff. We continued training through the spring. And then we went to Mull in Scotland for our open, where the water was 4?C.
'We did lots of scuba diving, two or three dives a day, and I did that every year, back to Scotland with the wrecks and our night dives, or in the North Atlantic. It was tough stuff, freezing cold! Being students, we had wetsuits, but we wished we had drysuits. We were all skinny. And the place was just awash with scallops - you could pretty much grab dinner on the way out, after the last dive. Those were the days!'
Leaving the UK in 1982 marked Sellers' last UK dive. 'Which is sad, because the diving off Scotland in particular is really spectacular. I'd like to do that again - with a better suit!'
Since emigrating to the States and becoming a US citizen in 1991, Sellers has dived in Hawaii 'quite a bit', Florida, Cozumel and Bermuda. 'I've stuck to the warm water since leaving the UK. Cozumel was the most spectacular for sea life - it has a sea park and
a huge drop-off. It's a good drift-dive, with a wall going up and down to infinity. You can just float there and watch the fish charging around.'
In Bermuda, Sellers traded in BSAC certification for a PADI card - he says it makes getting air easier.
'Bermuda doesn't have Cozumel's topography but it does have Civil War wrecks. Blockade-runners were sailing between Bermuda and the Confederate States and there are lots of reef wrecks. I saw a paddle-wheeler just lying there.
'Hawaii is like a Disney marine park - lots of people. Cozumel is not crowded at all and it's a good all-rounder - it has wrecks, sea life and lots of different species of fish. Scotland stands out with all the war wrecks but it was the coldest, the toughest on the system. If you're British, you're a bit short on money and you have good sinuses, go to Scotland.'

Dr Nicholas J M Patrick
Born: North Yorkshire
Occupation: NASA astronaut since 1998.
Space flights: One Space Shuttle mission in 2006.

NICHOLAS PATRICK'S PADI DIVE LOG starts in 1989, after his master's degree in Cambridge (England) but before his doctorate from MIT in Cambridge (Massachusetts).
'I obtained my Open Water and Advanced certificates in the North Shore area of Boston,' he says. 'I travelled up to York, Maine, for dives there too. Later on in my diving career, I did dives from a boat in Martha's Vineyard and Cape Cod, with all the wrecks.'
Patrick became a US citizen in 1994 and moved to Houston in '98. 'It's said that the best diving in the Houston area is to be found at the local airports. Since I've lived there, I've enjoyed 'local' diving venues such as Seattle, Jamaica, Costa Rica and Hawaii.'
Patrick recalls a coldwater dive that landed him in hot water. 'My wife and I travelled to Friday Harbour, near Seattle, right after she received her certification. That was the coldest water I've ever been in. It was frigid. My wife was not very happy with me, but because it was cold, the marine life was completely different. For example, we saw huge rock crabs.'
The tropics can have their own challenges. 'In Jamaica, the water is lovely and clear. At the end of my dive,
I was escorted by a remora up the anchorline to the boat. I carefully tried to brush it off my legs. Our tour guide had that Jamaican look of 'Don't worry; be happy'. Then the remora went for him - suddenly his attitude changed from 'No problem' to 'Do as I say and not as I do' as he tried to brush it off his legs!'
Patrick enjoys diving in Hawaii: 'I've had a wall dive in Maui, visited Red Hill and seen blacktip sharks, and done a night dive on Oahu Beach, in heavy surf. That was interesting, both getting in and out of the water!'
In 2002, Patrick was certified as a Rescue Diver in the Blue Lagoon in Huntsville, Texas: 'It's sandy and shallow, with no fish, but it's a good place to learn.' He took the course to help him get the most out of his next dive - a mission at the Aquarius habitat.
Even the preparatory work for NEEMO 6 involved many fascinating dives, with the crew training at Conch Reef in the Florida Keys and visiting Jules' Undersea Lodge in Key Largo's Emerald Lagoon.
'It's a habitat where you can rent a room, essentially a two-room underwater hotel. The pressure is kept at two atmospheres, which was good training for us and the high pressure of Aquarius.'
Nicholas Patrick describes living on a reef for 10 days as the highlight of his scuba career. 'We had a cave-diving rig in NEEMO and treated the mission as a series of overhead-environment dives. Physically we could have returned to the surface, as Aquarius lies in open water, but such an ascent might have caused the bends.
'So we operated as if we were exploring a cave, with no immediate return to the surface possible.'
For several years until last December, training for his first Shuttle flight consumed all Patrick's spare time, with diving holidays on hold in favour of the ultimate dive aboard Discovery. Now, space mission accomplished, Patrick confirms that he has unfinished business with scuba: 'I had originally intended, and still intend, to become a Divemaster.'

Sunita L Williams
(Commander, US Navy)
Born: Euclid, Ohio
Occupation: NASA astronaut since 1998
Space flights: Two Space Shuttle missions (2006 ascent only with one EVA and summer 2007, descent only); one ISS mission (2006-present, three EVAs). Williams holds the world record for time spent spacewalking by a woman.

SUNI WILLIAMS IS CURRENTLY ORBITING EARTH above us once every 90 minutes in the International Space Station. In her pre-flight interview with DIVER, she discussed enthusiastically her pathway to becoming scuba-certified, her nine-day aquanaut adventure, and the diver who influenced her most.
Unlike her career in the US Navy, when it came to water Williams started at the top and worked her way down. 'I was a competitive swimmer, and at the Naval Academy I participated in women's swimming. My sponsor was a saturation diver.
'During our service selection evening, when billets are made available to the graduating class, there was a diving and salvage billet, but my class rank wasn't high enough. I had 20/20 vision, so I became a pilot instead.'
But even learning to fly a helicopter didn't quite quench Williams' thirst for that other wild blue yonder. 'While attending flight school at Pensacola, I decided to ask if I could go to the Navy scuba school in Panama City [Florida]. So I got to sign up for Basic Diving Officer school.
'I was there for three months, and learned to dive in murky waters. Later, in San Diego, we were running degaussing cables under aircraft-carriers. I learned to be calm. You never knew what you'd find in the water.'
Suni Williams' nine-day NEEMO 2 expedition started with her getting into her suit and diving. 'It was good EVA training. The mission was similar to a saturation dive. The experience was spectacular, just like living in space.
'Our main task was hard-hatting to accomplish construction. NEEMO increases your comfort level with the water and with extreme situations. You practise problem-solving.
'It's good training for the ISS and it gave me an amazing view of the world - the fish, the sea life. We would try to finish our tasks 10 minutes earlier than scheduled, so my dive buddy and I would have time to just look around. Everything under water lives so symbiotically. Peggy Whitson jokes that if aliens exist, they won't look weirder than sea life.'
Finally, Suni Williams pays tribute to the saturation diver who sponsored her at the Naval Academy. '
A major influence in my life has been John Paul Johnson. He helped me to see how to get along with everyone - which is valuable training when you're stuck in the desat chamber with a group of people. He's the one who put a bug in my ear about diving.'