Sandia National Laboratories

Media contact:
Neal Singer (505) 845-7078

Sandia sends sensors into space to detect nuclear blasts globally

GPS satellite-based sensors can locate prohibited nuclear detonations

ALBUQUERQUE, N.M. -- Imagine you're in charge of a collection of sensors,
flying in formation on one of 31 U.S. Air Force satellites in medium Earth
orbit.

The satellite itself is part of the Air Force's Global Positioning System,
which lets truckers, hunters, and lost city drivers know exactly where they
are.

But from your point of view, the satellites are perfect platforms for a
collection of sensors to detect and triangulate airborne or space-based
nuclear explosions anywhere they may occur.

In the past, of course, detection has been no problem -- there haven't been
any above-ground explosions for decades.

On the other hand, there could be one anytime. And the country that did it
might deny doing it if its leaders didn't believe the U.S. could track it.

So sensors have to be ready to detect a real explosion, and do so through a
forest of potential false alarms: There are lightning bolts that occur more
than once per second, energetic particles from the Van Allen radiation belt
that collide with electronics on the satellite, a welter of "noise" from
cell phone communications, and meteors.

Sandia -- a National Nuclear Security Administration laboratory -- has a
long history of developing components of the nuclear detonation detection
system, in cooperation with the U.S. Air Force.

"What was tricky in the early sensor placements," says Sandia National
Laboratories project chief engineer Steve Yearout, "is that we did not have
a good idea what our observations of the environment would look like from
the standpoint of space. Looking at Earth with sensors was new and not well
understood -- the background noise, the clutter."

Yearout speaks from experience. No matter which GPS satellite the sensors
fly on, he has been there to turn them on and test their responses in the
sky. He's overseen an average of two payload launches a year for the past 25
years, packaged in boxes that resemble several small suitcases.

Sandia provides optical and electromagnetic pulse (EMP) sensors, radio
frequency equipment, and the main processors that coordinate all commands,
as well as return sensor output back to ground. Los Alamos National
Laboratory provides X-ray and particle detectors.

"We also have a state-of-health telemetry system that allows us to see how
our system is functioning," says Yearout.

Perfectly synchronized atomic clocks on all satellites mean that telemetry,
geometry, and computer programs working together can accurately define the
position of any point of interest, whether a lightning bolt or a nuclear
explosion.

Difficult as it is to test equipment without the environment in which it
will be used, the Sandia group's sensor packages have performed
exceptionally well over the years.

This success includes surviving one faulty rocket that exploded on takeoff
in the 1980s. A number of the sensors survived and were still operable. "We
build pretty good stuff," says Yearout.

The next launch is scheduled for October.

Funding and oversight for the development, construction, and on-orbit
support of the sensors is provided for by the Office of Nonproliferation
Research and Development in the National Nuclear Security Administration
(NNSA).

The sensor components are delivered by Sandia to an Air Force contractor,
either Boeing or Lockheed Martin, to integrate onto the GPS satellite
package. The Air Force launches GPS satellites from Cape Canaveral, Florida,
and then, once in orbit, the sensor components are switched on remotely by
Yearout and his teammates from Sandia, LANL, and the U.S. Air Force.

Sandia is a multiprogram laboratory operated by Sandia Corporation, a
Lockheed Martin company, for the U.S. Department of Energy's National
Nuclear Security Administration. With main facilities in Albuquerque, N.M.,
and Livermore, Calif., Sandia has major R&D responsibilities in national
security, energy and environmental technologies, and economic
competitiveness.

IMAGE CAPTIONS:

[Image 1:
http://www.sandia.gov/news/resources/releases/2008/images/GPS1.jpg (7.4MB)]
Sandia engineer Steve Yearout displays a 1/15 scale model of a NAVSTAR Block
IIR GPS satellite. (Photo by Randy Montoya)

[Image 2:
http://www.sandia.gov/news/resources/releases/2008/images/GPS2.jpg (4.12MB)]
Of the 51 GPS satellite launches with which Steve Yearout has been involved,
only this one failed. (Photo by Steve Yearout)
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