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Underwater Training For ISS Crew
By Yuri Karash
Special to SPACE.com
posted: 02:14 pm ET
28 June 2000
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First ISS Crew Practices EVA Procedures in Star City's Water Tank When the first crew of the International Space Station (ISS) moves into its new outer-space home in September, the physical art of working outside the orbital outpost will be one of the most challenging parts of the job. Here on Earth the crew's commander Bill Shepherd, along with Yuri Gidzenko, Soyuz vehicle commander and Sergey Krikalev, the flight engineer, prepare for the challenges of maneuvering in space by working underwater. Their training grounds are the hydro laboratory at the Johnson Space Center near Houston and the neutral buoyancy tank at Gagarin Cosmonauts' Training Center (Star City), near Moscow. 
Shepherd and Krikalev work underwater, helped by their scuba-diving assistants . The cosmonauts' submerged 'space station' The Russian neutral-buoyancy tank, located in Star City, is a huge water reservoir, 75 feet (23 meters) in diameter and 40 feet (12 meters) deep, with a capacity of 176,580 cubic feet (5000 cubic meters). Cosmonauts usually practice their extravehicular activity (EVA) on a mock-up of the station in which they are supposed to fly. It is installed on a perforated platform that supports up to 15.4 tons. The platform is lowered into the water before the training and brought up again afterwards. The current "underwater space station" is a mock-up of the ISS segments that include the Zvezda service module, set to be launched this July, and a part of the Zarya module already in orbit, linked to the American "Unity" section. ~ 
Shepherd is helped into his suit. Heavy suits Cosmonauts and astronauts use regular Orlan-type EVA suits during their underwater training in Star City. Each suit weighs 220 pounds (100 kilograms).Unlike an EVA spacesuit, the suit for underwater training has no textile cover on its steel frame and has no autonomous life-support system. Coolant, power and air are supplied through hoses and cables from the facility. The training suit also has special envelopes on its chest, hands and legs. Neutral buoyancy is created by putting weights in these envelopes. "Each suit can withstand up to 40 underwater training sessions," said a former cosmonaut-candidate Air Force Col. Nikolai Grekov, the Center's chief of cosmonaut training in the conditions of a hostile environment. "Then it needs to be refurbished. After 150 sessions it is sent to its manufacturer for a major overhaul." 
Shepherd is lowered into the water. Before donning the suit, each cosmonaut puts on regular long cotton underwear and a special cooling garment over it. This garment looks like an overall made of synthetic net interlaced with plastic pipes. Coolant runs through these pipes, taking excessive heat away from the trainees' bodies. EVA-training suits wait for trainees on the board of the tank. Each suit is located on a special stand in a vertical position. While a cosmonaut can don his suit in the weightless environment of space without extra help, a trainee on Earth needs assistance. After trainees are sealed into their suits, they are lowered into the water by two cranes permanently installed on the board of the tank. Each trainee is lowered by his or her own crane. Normally, two crew members work underwater. Recently, the Center's command decided to train three crewmembers at once. The third trainee wears a light diver's suit. ~ 'Guardian angels' with flippers "Training usually lasts from 9 a.m. till 2 p.m. The...longest training [ever] lasted [is] about seven hours," said Grekov. "We could make it last even longer but the scuba divers may get cold." At 87 degrees Fahrenheit (31 degrees Celsius), the temperature of the water assures their comfort. 
The Service Module mock-up in Star City. There are two major categories of scuba divers in Star City: professional divers who are Navy warrant officers and City Air Force officers, particularly cosmonaut-candidates. The latter gain their necessary EVA experience while helping their fellow cosmonauts during underwater training. Although the tank water is warmer than in any tropical sea, scuba divers often take a sauna after training to warm up. It is also chlorinated, though less so than the average swimming pool. The lower level is maintained for two reasons. First, it prevents chlorine poisoning and second -- it's easier on the underwater equipment. During each training session there are at least seven scuba divers in the tank who assure safety, as well as help cosmonauts dressed in the heavy EVA suits to move around. "Safety of the training is paramount," said Grekov. "There is a rule that each trainee, in case of [an] emergency, must be pulled out of the water in four minutes at most." An emergency car is on duty during each EVA training and a decompression chamber is ready to receive trainees in case if any of them is affected by the water pressure. ~ EVA training -- Russian and American style: The differences "It is very hard to find real differences between Russian and U.S. EVA suites," says Bill Shepherd. "The equipment is different. In the U.S. training we try to put people in places where their feet are tied down. The Americans call it foot restrainers, while the Russians call it anchors." "We have more in common than differences," says Dina Barcoli, Johnson Space Center EVA representative to Star City. "The cultural differences is really what it amounts to. Having meetings and what to talk about and how to go about saying it is really one of the biggest differences that we have. But we have such a common goal that works out, and we end up friends in the end." The real difference between Russian and U.S. EVA training, however, is the training philosophy. 
The cylindrical building in Star City where the neutral-buoyancy tank is located. "The Americans have very narrowly focused training," said Grekov. "They practice underwater only those procedures which they will do in orbit. The Russians, however, teach cosmonauts the overall EVA methodology, which enables the crews to cope with many unpredicted situations in space." Grekov's opinion is echoed by Shepherd. "In the U.S. the training is very carefully laid out to exactly what the job is," said the first ISS crew commander. "The work is practiced from six to eight times. You practice exactly how you'll be positioned, how you'll place your tools." "The U.S. specialist may have a good reason for such [an] approach," says Krikalev. "They have short-duration flights where everything is planned ahead and there are very few unexpected things. Besides, their EVAs are always followed by flight controllers on Earth who can give astronauts advice how to do this or that procedure." "Russians are the different story," said Krikalev. "First, they do long-duration flights, which always present a number of unexpected challenges. Second, when the Russian crews do their EVAs, Mir is often out of radio contact with the Mission Control Center meaning that the cosmonauts have to rely only on their knowledge and experience."
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