Most news stories about Helium-3 discuss its potential as a future energy source, due to its abundance on the Moon's surface. But, here on Earth, it's a rare substance that's getting rarer. And that worries the Pentagon, which uses Helium-3 as a key ingredient in equipment to detect nuclear smuggling.
The sensors made with Helium-3 are designed to detect uranium and plutonium that could be components of "dirty bombs"—which would use conventional explosives to disperse radioactive material and potentially contaminate a densely populated urban area.
The neutrons emitted by plutonium and uranium are difficult to detect, but when Helium-3 is hit by a stray neutron, it creates a charged particle, which is readily detected and measured. Although there are other ways to build detectors, engineers prefer Helium-3 because it is nontoxic, nonradioactive and extremely accurate.
In space, Helium-3 travels along solar winds, but Earth's magnetic field pushes it away. (Thanks to its negligible magnetic field, the Moon doesn't suffer from this fate.) As such, the only way to obtain the substance on Earth is as a byproduct of the radioactive decay of tritium, which is a material used in nuclear warheads.
But, over the years, as Helium-3 has been collected from aging warheads, the supply of the substance has dwindled as the U.S. arsenal has grown smaller. Unfortunately, the agency responsible for gathering Helium-3—the Nation Nuclear Security Administration—never shared information about this shortage with the Department of Energy, which had already spent $230 million on the development of detectors that depend upon, you guessed it, Helium-3.
That has prompted the Pentagon's Defense Threat Reduction Agency to seek out new technologies that can be as accurate, or even better, than current detectors.
The Global Security Newswire reports:
The agency has awarded a $2.8 million contract to Alion Science and Technology of McLean, Va., to further its research into a next-generation detection system that utilizes bundles of thin copper tubes coated with boron….The current generation of Helium 3-powered detectors can alert authorities to the presence of a nearby radioactive source, but these systems cannot determine the direction from which the radiation is coming. Alion plans to use its Pentagon funding to give its boron-coated "straw" sensors the ability to pinpoint the direction of a source….beyond providing a drop-in replacement for Helium-3 detector components, this engineering effort opens up a number of possibilities for new or enhanced portable systems that can be carried into questionable areas or permanently installed to protect ports and depots.
The other option, of course, would be establishing mining operations on the Moon—though that would involve a longer time-frame than the Pentagon has in mind.