.Duo removing explosive Soyuz bolt in risky spacewalk
Two cosmonauts will float outside the international space station today to retrieve an explosive bolt from a Russian Soyuz capsule, a risky spacewalk ordered by officials on Earth to examine the leading suspect for the ship's two recent near-crash landings.
During the six-hour excursion, Sergei Volkov and Oleg Kononenko will retrieve an explosive bolt from one of five locking mechanisms that hold the capsule's crew compartment to a smaller instrumentaion and propulsion module.
The cosmonauts will also open the lock, ensuring it does not stick when the Soyuz, now docked to the station, descends to Earth in late October with Volkov, Kononenko and American space tourist Richard Garriott.
The unprecedented handling of an explosive bolt by the cosmonauts adds a risky dimension to the spacewalk but one Volkov and Kononenko should be able to navigate, experts said Wednesday.
The key for the cosmonauts is to work cautiously when removing electrical cables attached to the bolt. The cables transmit firing signals.
"The spacewalk is unusual. You can bet the crew will be very deliberate," said former NASA astronaut Tom Jones, an aerospace consultant who has participated in three spacewalks outside the space station. "But the added risk is probably not greater than the risk of the spacewalk itself."
Explosive bolts have been used extensively on spacecraft, including NASA's manned shuttle, and on military aircraft for decades while accruing a good safety record, said Arthur Draut, a professor of aeronautical sciences at the Embry-Riddle Aeronautical University in Prescott, Ariz.
"The technology is mature enough that handling the bolt is fairly safe," Draut said. "I don't see any danger from removing it."
Russian investigators suspect that similar explosive bolts misfired on two occasions when the capsule was to separate from a 5,200-pound propulsion unit as the Soyuz entered the atmosphere. As a result of a late separation, the capsule and its occupants endured a violent descent, first on Oct. 21 and most recently on April 19.
American Peggy Whitson was among three space travelers aboard the Soyuz that made the April landing on the plains of Kazakhstan, nearly 300 miles off course.
The six Russian, Malaysian, South Korean and American astronauts aboard the two capsules experienced gravitational forces twice the usual three to four "G's" of a Soyuz landing.
The risky spacewalk prompted safety reviews by American as well as Russian engineers, said flight director Bob Dempsey, who will supervise activities at NASA's Mission Control during the excursion.
"We have looked very carefully at the risks associated with removing a pyro-bolt," Dempsey said. "The Russians have looked at this for a long time and planned very carefully. Our specialists have looked at it very carefully. We are very confident this is a safe operation to do."
Russia's Mission Control will supervise the two cosmonauts as they remove a protective cover, unscrew the 3-inch-long explosive bolt with a wrench and place the device in an 8-inch-long blast-proof case. The bolt has the explosive force of an M-80 firecracker, and ground testing has demonstrated the steel case would contain an unexpected detonation, Dempsey said.
Nonetheless, Russian chief flight director Vladimir Solovyov offered Volkov and Kononenko fresh assurances for their safety during an exchange Wednesday.
"It cannot fire. You should not be concerned at all," Solovyov said in an English translation of his remarks.
The conversation included an explanation of how the bolt survived ground tests in which the device was subjected to forces equal to those from a sharp blow with a hammer.
"We know you will do great," added Solovyov, who instructed the two first-time spacewalkers to take their time.
The cosmonauts have rehearsed their activities for the past two weeks with Greg Chamitoff, the station's only American crew member.
"We've prepared so much, we are ready to get on with it," Volkov assured the Russian Mission Control chief.
The Russians plan to store the case enclosing the bolt in the space station until Volkov and Kononenko can return it to Earth in October for examination by investigators. Though the bolt is a suspect in the troubled landings, Russian experts have not ruled out another problem with the locking mechanism.
"To date, they have not come to a conclusive answer to the root cause," said NASA's Mike Suffredini, the space station program manager. "They continue to look at different scenarios."
Chamitoff will be seated inside the Soyuz throughout the unusual spacewalk as a safety measure.
The capsule is docked to the station's Russian airlock, which will be decompressed throughout the outing. If Chamitoff were not in the Soyuz, he would be cut off from his only escape to Earth if an emergency developed inside the station.
If an emergency would arise during the spacewalk, the cosmonauts are to climb into the Soyuz with Chamitoff. They would either steer the capsule to another port on the space station, where they could re-enter the orbital outpost, or make a descent to Earth.
The three-person Soyuz began its 40th year of operations in April.
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During the six-hour excursion, Sergei Volkov and Oleg Kononenko will retrieve an explosive bolt from one of five locking mechanisms that hold the capsule's crew compartment to a smaller instrumentaion and propulsion module.
The cosmonauts will also open the lock, ensuring it does not stick when the Soyuz, now docked to the station, descends to Earth in late October with Volkov, Kononenko and American space tourist Richard Garriott.
The unprecedented handling of an explosive bolt by the cosmonauts adds a risky dimension to the spacewalk but one Volkov and Kononenko should be able to navigate, experts said Wednesday.
The key for the cosmonauts is to work cautiously when removing electrical cables attached to the bolt. The cables transmit firing signals.
"The spacewalk is unusual. You can bet the crew will be very deliberate," said former NASA astronaut Tom Jones, an aerospace consultant who has participated in three spacewalks outside the space station. "But the added risk is probably not greater than the risk of the spacewalk itself."
Explosive bolts have been used extensively on spacecraft, including NASA's manned shuttle, and on military aircraft for decades while accruing a good safety record, said Arthur Draut, a professor of aeronautical sciences at the Embry-Riddle Aeronautical University in Prescott, Ariz.
"The technology is mature enough that handling the bolt is fairly safe," Draut said. "I don't see any danger from removing it."
Russian investigators suspect that similar explosive bolts misfired on two occasions when the capsule was to separate from a 5,200-pound propulsion unit as the Soyuz entered the atmosphere. As a result of a late separation, the capsule and its occupants endured a violent descent, first on Oct. 21 and most recently on April 19.
American Peggy Whitson was among three space travelers aboard the Soyuz that made the April landing on the plains of Kazakhstan, nearly 300 miles off course.
The six Russian, Malaysian, South Korean and American astronauts aboard the two capsules experienced gravitational forces twice the usual three to four "G's" of a Soyuz landing.
The risky spacewalk prompted safety reviews by American as well as Russian engineers, said flight director Bob Dempsey, who will supervise activities at NASA's Mission Control during the excursion.
"We have looked very carefully at the risks associated with removing a pyro-bolt," Dempsey said. "The Russians have looked at this for a long time and planned very carefully. Our specialists have looked at it very carefully. We are very confident this is a safe operation to do."
Russia's Mission Control will supervise the two cosmonauts as they remove a protective cover, unscrew the 3-inch-long explosive bolt with a wrench and place the device in an 8-inch-long blast-proof case. The bolt has the explosive force of an M-80 firecracker, and ground testing has demonstrated the steel case would contain an unexpected detonation, Dempsey said.
Nonetheless, Russian chief flight director Vladimir Solovyov offered Volkov and Kononenko fresh assurances for their safety during an exchange Wednesday.
"It cannot fire. You should not be concerned at all," Solovyov said in an English translation of his remarks.
The conversation included an explanation of how the bolt survived ground tests in which the device was subjected to forces equal to those from a sharp blow with a hammer.
"We know you will do great," added Solovyov, who instructed the two first-time spacewalkers to take their time.
The cosmonauts have rehearsed their activities for the past two weeks with Greg Chamitoff, the station's only American crew member.
"We've prepared so much, we are ready to get on with it," Volkov assured the Russian Mission Control chief.
The Russians plan to store the case enclosing the bolt in the space station until Volkov and Kononenko can return it to Earth in October for examination by investigators. Though the bolt is a suspect in the troubled landings, Russian experts have not ruled out another problem with the locking mechanism.
"To date, they have not come to a conclusive answer to the root cause," said NASA's Mike Suffredini, the space station program manager. "They continue to look at different scenarios."
Chamitoff will be seated inside the Soyuz throughout the unusual spacewalk as a safety measure.
The capsule is docked to the station's Russian airlock, which will be decompressed throughout the outing. If Chamitoff were not in the Soyuz, he would be cut off from his only escape to Earth if an emergency developed inside the station.
If an emergency would arise during the spacewalk, the cosmonauts are to climb into the Soyuz with Chamitoff. They would either steer the capsule to another port on the space station, where they could re-enter the orbital outpost, or make a descent to Earth.
The three-person Soyuz began its 40th year of operations in April.
chron
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