GPS Tracks Secret Nuke Tests

Global Positioning System satellite. Credit: NASA

You may be carrying in your pocket the

technology to detect clandestine nuclear tests.

New research into GPS

disturbances high up in Earth's ionosphere reveals that sometimes the

“noise” in the GPS signals are secret underground nuclear tests.

Not only that, but tests with archived GPS data not only detect the nukes, but can be

used to track the ionospheric noise back to its source.

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“That noise became our signal,”

said Dorota Grejner-Brzezinska, professor of Geodetic and

Geoinformation Engineering at Ohio State University. She was

addressing reporters Tuesday at a press conference at the American

Geophysical Union meeting in San Francisco. The research, she said,

started out as an attempt to identify and remove noise from the GPS


Like earthquakes, underground nuclear

blasts send pulses of acoustic energy up through the earth that

momentarily disturb the ionosphere. Those disturbances propagate outward

through the ionosphere like waves from a stone thrown into a pond. As

the ionospheric disturbance passes between a GPS satellite and a GPS

receiver on the ground, there is a noticeable blip error in the data.

Add together lots of other such errors from the same wave passing

between multiple receivers and satellites, and you get a lot of very

specific data that points back to a the source.

“It's very similar to seismological

detection of an epicenter (of an earthquake),” explained Jihye

Park, a post-doctoral researcher at Ohio State University. In fact

the same methods can be used as those employed by seismologists, she


They applied their technique to

archived data and found clear signals of US nuclear tests from the

1990s as well as underground detonations in North Korea.

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From GPS noise, a signal achievement

The new technique was verified by yet

another unlikely blast detection tool: The Very Large Array (VLA) in

New Mexico.

“We have to do the same thing:

Correct for ionospheric distortion,” said radio astronomer Joseph

Helmboldt of the Naval Research Laboratory. The VLA is made up of

lots of smaller radio telescopes working together, and since each one

looks though a slightly different patch of the ionosphere, any

disturbances have to be accounted for and corrected, he explained.

“We paired with the group from Ohio

State to see if we could see these tests,” Helmboldt said. They

used archived radio data from a 1992 nuclear test in Nevada and, sure

enough, saw the fast-moving signal crossing the sky over the VLA.

Despite being a lot more compact than a global GPS array, the radio

telescope did help confirm what the GPS folks were seeing, he said.

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Although the GPS/radio telescope method

is not an officially approved method for monitoring for secret

nuclear tests, it does provide an additional method to verify what is

detected by seismic networks, said Grejner-Brzezinska.

“Both methods are quite effective,”

said Grejner-Brzezinska. And GPS, like seismic data, is available in

real time, so can be put to work quickly – which is always good

when people are nervous and want to know who has got a nuke.

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