Giant Meteor Goes Boom for Science

The colossal meteor that burst through the skies over Russia on Feb. 15 at more than 40,000 miles per hour and exploded with the force of 30 atomic bombs came as a surprise to astronomers and common citizens alike.

But the repercussions of the 10,000-ton meteor, estimated at 17 meters (55 feet) wide and the largest recorded since 1908, will go well beyond the scores of injuries and broken windows across the Russian city of Chelyabinsk. Because of the remarkable scale of the fireball’s blast, scientists will reap a harvest of valuable data from a multitude of instruments and monitoring devices that recorded the event.

One scientist looking forward to the wealth of new information that awaits analysis across several scientific disciplines is Michael Hedlin, the head of the Laboratory for Atmospheric Acoustics at Scripps Institution of Oceanography at UC San Diego.

Hedlin will discuss the Chelyabinsk meteor and its unique offerings to scientific research on April 8 at Birch Aquarium at Scripps’s Jeffrey B. Graham Perspectives on Ocean Science Lecture Series

Hedlin’s expertise lies in infrasound, the very low frequency sound waves—beyond human hearing levels—that can travel thousands of miles following major events such as volcanoes and lighting strikes.

The Chelyabinsk meteor generated a very broad spectrum of sound, including infrasound, when it burst at roughly 30 kilometers (18.6 miles) in the stratosphere, said Hedlin, who oversees an infrasound instrument station at Scripps’s Piñon Flat Observatory in eastern San Diego County.

Hedlin and his colleagues are analyzing infrasound data captured by instruments in northern Kazakhstan, the closest of such devices to record the acoustic energy from the February event, although large events such as the Chelyabinsk meteor can be detected around the world (and also was picked up by the Piñon Flat Observatory).

Instruments that record earthquakes also picked up the meteor’s ground-shaking impact, including seismic devices operated by the global Project IDA program based at Scripps. Thousands of miles from the blast in the U.S., the National Science Foundation’s EarthScope-USArray and its cluster of transportable seismo-acoustic stations picked up clear acoustic signals of the meteor’s burst.

Hedlin believes such data will be beneficial beyond immediate scientific studies and will be applied to improving global monitoring of both natural and man-made blast events.

Infrasound, along with sensors for seismic signals, ocean-based acoustics, and radioactive particles, is part of the Comprehensive Test Ban Treaty Organization (CTBTO), a group that monitors the globe for nuclear tests. The organization’s instruments, for example, were used to pinpoint the Feb. 11 North Korean nuclear test that stirred political unrest around the world.

“The Chelyabinsk meteor is very valuable not only for basic research into the generation of infrasound and its propagation to great ranges through a constantly varying atmosphere, but also serves as a test of our ability to use the nuclear monitoring system to detect and characterize atmospheric explosions,” said Hedlin.

RSVP for the April 8 Birch Aquarium at Scripps lecture by Michael Hedlin at: http://aquarium.ucsd.edu/Education/Public_Programs/Adult_Programs/Lectures

-- Mario C. Aguilera