The rumble of hypersonic objects tearing through the atmosphere can be routinely detected by sensitive infrasound sensors [Brown et al., 2002]. Meteors and reentering spacecraft are the most common hypersonic sources, although supersonic aircraft generate comparable signatures. This article concentrates on two exceptionally energetic events: the tragic Columbia reentry of 1 February 2003 (STS-107) and the 23 April 2001 superbolide explosion.

On 23 April 2001, a large meteor exploded at a height of ˜28.5 km between Hawaii and California. With an estimated explosive energy of ˜10 k of TNT, this event catalyzed the U.S. infrasound community to work with other sectors of government, academia, and industry to provide rapid analyses of any available infrasound, seismic, hydroacoustic, and satellite data that would help identify the explosion source and determine its location.