US astronaut Peggy Whitson outside the International Space Staion.

Highlights Peggy Whitson and Shane Kimbrough accidentally lost a fabric shield

The fabric shield provides a barrier from exteme temperature changes

Whitson broke Sunita Williams' record for most spacewalks by a woman

NASA astronauts on a spacewalk Thursday accidentally lost a fabric shield needed for the International Space Station - a minor setback in what was otherwise a record-setting mission for one of the crew members.Astronauts Peggy Whitson and Shane Kimbrough were working on an area of the space station where a docking port had been disconnected and moved last week. They were in the process of using four large cloth panels to cover the access point where the docking port had been when one of the fabric shields suddenly drifted away and floated off into space.There was audible frustration in Whitson's voice as she reported the sequence of events to Mission Control, according to the Associated Press.Up until that point, about 3 1/2 hours into the spacewalk, everything had been going smoothly, NASA spokesman Dan Huot told The Washington Post. It's unclear what happened or who was responsible for the lost fabric shield."The team will go back and look at what the chain of events were, but essentially it was untethered," Huot said.Covering the access point for the docking port was critical, Huot added, to protect that area of the module from what NASA calls "MMOD" (micro-meteoroids or orbital debris) - or, in layman's terms, "basically any space junk, any space rocks that might impact it."The shield also provides a barrier from extreme temperature changes.Because it was such an important task, ground teams at Mission Control scrambled to find a solution for the quarter of the access point left exposed.Immediately, teams gathered in a Mission Control office that contained replicas of everything up in space, Huot said.They quickly laid things on the floor and devised a way for the astronauts to use a different piece of cloth and wire ties as a substitute for the lost shield."It was spur of the moment, completely unplanned," Huot said. "They got presented with a problem and the ingenuity kicked in."Each of the four cloth shields weighs 18 pounds and is a little over 5 feet long, 2 feet wide and almost 3 inches thick, Huot said.It was the first time NASA had lost a fabric shield during a spacewalk - though astronauts have lost other items during spacewalks before."Sometimes bolts will go," Huot said. "There was one spacewalk where we lost an entire bag of tools."Eventually, he said, the lost fabric shield will degrade, then burn up upon reentry into the Earth's atmosphere. However, because lost items in space run the risk of returning in orbit and damaging the space station, Mission Control closely monitored the lost cloth at first. It was spotted again one orbit, or about 90 minutes, later - at which point officials determined there was no risk it would come back into contact with the station.The rest of the spacewalk, which clocked in at seven hours and four minutes, went as planned, Huot said.Of note: Part of the way through the spacewalk, Whitson set the record for the female astronaut with the most cumulative spacewalking time, at 53 hours and 22 minutes. She broke the previous record, 50 hours and 40 minutes, held by American astronaut Sunita "Suni" Williams.It was Whitson's eighth spacewalk, also a record for a female astronaut.Russian cosmonaut Anatoly Solovyev holds the all-time spacewalking record, with 16 separate spacewalks and over 82 hours of cumulative spacewalking time.

According to the AP, Whitson is scheduled to return to Earth in June but may extend her time in space for an additional three months, until September.