Sunday, July 26, 2009

Live In Orbit: Astronauts On Guard For 5th Spacewalk

NASA's 29th shuttle mission devoted to the assembly of the International Space Station so far has been exceedingly successful, but the skipper of shuttle Endeavour knows not to rest on laurels.

Mission specialists Chris Cassidy and Tom Marshburn will head outside the station on Monday on the fifth and final spacewalk planned during Endeavour's lengthy stay at the outpost.

Clad in protective spacesuits, the astronauts nonetheless will be working once again in a vacuum environment where a small tear could led to certain disaster.

"All in all, I think it's an extremely successful mission," Endeavour mission commander Mark Polansky told reporters in a space-to-ground news conference today.

"But I think we're all keenly aware that (spacewalks) carry some risk to them, and so we're going to be very, very deliberate and careful about the last (spacewalk) because in my book, the last one you do is always the one you have to watch out for the most."

Polansky and 12 others on the joined shuttle-station complex took time out to talk with reporters at NASA's Johnson Space Center in Houston, Kennedy Space Center and a Canadian Space Agency facility.

The total of 13 represents the most people onboard the station simultaneously and all of the project's major partners -- the U.S., Russia, Canada, Japan and Europe -- are represented on the orbiting outpost for the first time.

Veteran NASA astronaut Dave Wolf, who lived and worked aboard Russia's Mir space station during the 1990s, said he is immensely impressed with the International Space Station.

"It's really fascinating to be here," Wolf said.

"I'm looking down a corridor, maybe 60, 80 feet, through several modules into a Russian segment. To my left is a European segment, to my right is a Japanese segment, a U.S. space shuttle behind me," he said.

"And as you go through here, you hear different languages, you hear different music -- It's like going around the world within the spacecraft as it goes around."

The product of 15 nations and more than 100,000 people working on three continents, the station now weighs about 340 tons -- more than double the size of the Mir station -- and is considered one of the greatest engineering achievements of all time.

"We've put together a vehicle that is truly international, and brought together a truly international crew representing the whole world," Wolf said. "We're undertaking, perhaps, one of the most spectacular engineering achievements that humans have ever conducted. And so it's just fabulous in many dimensions."

The view apparently is incomparable, and veteran space fliers note changes to the planet over the years.

"It's still a strikingly beautiful view," said Canadian astronaut Bob Thirsk, who flew on a shuttle mission in the 1990s and now is a flight engineer on the station.

"I am impressed by the thinness of the atmosphere. It's a very thin veil of atmosphere around the Earth that keeps us alive."

Station passes over British Columbia have made a great impression.

"It's probably just a perception, but I just have the feeling that the glaciers are melting, the snow capping the mountains is less than it was 12 years ago when I flew last time," Thirsk said.

"It's probably just a perception, but that saddens me a little bit," he said. "Most of the time when I look out the window, I'm in awe. But there are some effects of the human destruction of the Earth as well."

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