The trip outside was the third for Korzun, an experienced Russian cosmonaut who made two spacewalks during his 1996 stay aboard the space station Mir -- a tour of duty that included a spacecraft fire.

For NASA astronaut Whitson, a rookie scientist from Iowa, this was her first spacewalk and like so many of her colleagues sounded completely awestruck upon seeing Earth for the first time from the other side of a spaceship window.

"Ah, this is beautiful," she said, laughing as the station cruised 230 miles (370 kilometers) over the Atlantic Ocean just east of South America.

Later, Whitson was suspended at the end of a 50-foot-long (15-meter-long) crane and swung away from the station by Korzun. He was operating the Russian Strela boom as they transferred the package of debris shields from their stowage location to where they had to be attached to the Zvezda service module.

Mission managers had likened the maneuver to being hung out at the end of flagpole over the Grand Canyon, providing a stomach-turning yet splendid view. Unfortunately for Whitson, when the big moment came it was in darkness.

"I was hoping for a sunrise here so I can see," she told Korzun in English.

In fact, the Russian-American duo seamlessly used both of their languages throughout the spacewalk -- in general using Russian for technical discussions and English for tips, suggestions and comments about how things were going.

Once the pair made it outside everything went like clockwork, but reaching the vacuum of space took a little more effort than planned.

Korzun and Whitson were scheduled to begin their spacewalk at 3:40 a.m. EDT (0840 GMT). However just moments of opening the hatch of their Pirs airlock and docking module they both received caution and warning alarms that indicated their Russian Orlan spacesuits were leaking oxygen.

A quick round of troubleshooting by flight controllers near Moscow determined the problem: a missed step during spacewalk preparations, valves on the primary oxygen bottles inside both suits, were not configured properly, preventing any oxygen from flowing through the suits.

When the spacewalkers disconnected their suits from lines supplying power and air from the space station --one of the final steps before opening the hatch -- the suit sensors thought they detected a leak and in turn that activated the suits' backup oxygen supply.

To fix the problem the crew had to re-pressurize the Pirs airlock and open the back panel of their suits. Korzun actually doffed his spacesuit and reconfigured his own oxygen system, then fixed Whitson's. Exposed again to nitrogen in the air, the crew had to repeat the pre-breathing of pure oxygen before depressurizing the airlock -- a necessary step to avoid getting "the bends."

By the time all of this could be done, one hour and 43 minutes had passed.

Russian mission managers made the decision to cut short the spacewalk for two reasons. There was concern about the overall length of the crew day and about the amount of lithium hydroxide available that is used to scrub carbon dioxide from both of the spacesuits' air.

As a result, two tasks involving the measurement and inspection of steering thruster residue that clings to the station's skin were put off to another spacewalk.

A second spacewalk for the Expedition Five crew, this one by Korzun and flight engineer Sergei Treschev, is scheduled for next Friday. But Russian mission managers already are thinking about delaying that second spacewalk to Aug. 28, Navias said.

"That has been suggested by the Russian flight control team, not confirmed yet," Navias said.

It's possible that the tasks missed today will be moved to the second spacewalk, which itself already had a full six hours of various jobs assigned to it.

By the numbers, today's spacewalk was the 17th to be staged from the space station. Including shuttle-based spacewalks, astronauts and cosmonauts have spent a total of 260 hours and 23 minutes floating around the outside of the frontier outpost.