Thousands of scientific experiments have been put on hold for days after the US government sent a plane equipped with radiation monitors over the Los Alamos nuclear laboratory as a 110-square-mile wildfire burned at its doorstep.
Lab authorities described the monitoring as a precaution, and they, along with outside experts on nuclear engineering, expressed confidence that the blaze would not scatter radioactive material, as some in surrounding communities feared.
The pillars of smoke that can be seen as far as Albuquerque, 60 miles away, have people on edge. The fire has also cast a haze as far away as Kansas, but officials said they had analysed samples taken from some of the lab's monitors and the results showed nothing abnormal in the smoke.
Lab director Charles McMillan said: "Our facilities, our nuclear materials are all safe, they're accounted for and they're protected."
The twin-engine plane, which can take digital photographs and video as well as thermal and night images, was sent to New York City to take air samples after the September 11, 2001 terrorist attacks.
It has flown over wildfires and areas damaged by Hurricane Katrina, monitored the 2002 Winter Olympics in Salt Lake City and also helped locate debris from the disintegrated space shuttle Columbia.
In a testament to the sophisticated research done at Los Alamos, the plane was developed with technology from the lab, the desert installation that built the atomic bomb during the Second World War.