A U.S. Air Force plane swept down over the coldest spot on Earth today, searching in the dark polar winter for a C-shaped chain of blazing barrels--the drop point for emergency medical supplies needed by a U.S. worker who had discovered a lump in her breast.

The pressure was intense on the 23-person crew to make the drop quickly and accurately, as they knew they would have little extra fuel on the 6,375-mile round trip.

And with driving snow reducing visibility to less than five miles, they had just minutes to get in the right position for drop-off as they approached at 200 mph. They wore night-vision goggles and oxygen masks as they flew 700 feet above the South Pole--and 10,000 feet above sea level.

"It was worth the risk. The person who needed the supplies down there should be able to get them now, and hopefully that will hold them over until they can get her off the continent in the fall," Air Force Capt. John Hall told CNN upon returning to Christchurch, New Zealand.

Staff at the research base had just seven minutes to collect the six bundles before the minus 67-degree cold damaged or destroyed the drugs and equipment they carried.

"I believe they got them inside before the cold got to them," said Antarctic support group commander Col. Richard Saburro, adding that the equipment still needed to be checked for damage from the drop.

The 47-year-old American woman, whose name was not disclosed, works on the support staff at the Amundsen-Scott South Pole Station, a geodesic dome that houses a research unit of the U.S. National Science Foundation. Forty-one people work there, researching everything from ozone to paleontology. The station is 840 miles from the nearest populated site, another research station on the Antarctic coast.

Because of extreme weather conditions, people do not leave the South Pole from March through October. There have been only three emergency medical flights out of the station over the past 25 years.

The woman recently had a biopsy and a battery of tests with the base physician and the results were sent to doctors in the United States on the Internet. The treatment they directed was not disclosed.

The crew, from McChord Air Force Base outside Seattle, passed over the target twice to drop the six bundles of equipment, medical supplies, fresh fruits and vegetables and mail. There are not usually supply drops to the base in winter.

Among the equipment were two 380-pound ultrasound scanners. Two were sent to ensure that at least one was recovered undamaged from the ice.

"The worst is over," Saburro said. "We are all very relieved at this point."

CAPTION: Left: Air Force C-141 Starlifter takes off from Christchurch, New Zealand en route to the South Pole.