UH investigates
Earth’s innards

Scientists are trying to determine whether
the planet's center is a natural reactor

University of Hawaii physicists are working with Makai Ocean Engineering on a project that could reveal what's inside the Earth.

They're developing a 60-foot sphere to detect ghostly neutrinos and anti-neutrinos in Hawaii's deep ocean.

Neutrinos, which have no electric charge, are one of the fundamental particles making up the universe. Anti-neutrinos are the anti-matter counterpart to neutrinos and they can be created in fission reactors.

There is some local evidence supporting a theory that there is a natural reactor at the center of the earth, said UH physicist John Learned.

"If there is a reactor, it could be the source of heat that drives plumes, that makes the magnetic field, that causes continental drift and causes our hotspot," he said. "If there really is a reactor at the center of the earth, it would be an incredibly big discovery."

Learned said a site hasn't been selected, but he favors sinking the sphere -- dubbed Hanohano for "excellent" -- west of the Big Island.

Tore Leraand, engineer working on the design, said the huge undersea sphere is a construction challenge.

It will be filled with mineral oil for colliding subatomic particles, and instruments to measure light and energy produced by the interaction.

The size has already grown from 1,000 cubic meters of fluid to 4,000 cubic meters, which quadruples the volume and requires a design change, Leraand said.

The scientists are calling antineutrinos detected from radioactive rocks "geoneutrinos" because they're geologically produced rather than from the sun and cosmic rays.

Learned said the first international meeting about neutrino geophysics and the ocean detector will be held Dec. 14-16 at the East-West Center.

Learned is leader of a UH team participating in the experiment, with 87 scientists from four countries.

Scientists say their findings, reported in the July issue of the journal Nature, are the first step toward understanding the earth's structure. The measurements will enable them to determine the planet's chemical composition and heat flow, they said.

"It's very hard to know what's in there ... and composition of the earth is a big debate," Learned said.

Geologists have had to rely on seismic analysis to tell them what's happening in the earth's interior or guess what the composition is based on meteorites, Learned said. "Geologists are arguing forever about which kind of meteorites represent the primordial composition of earth. They don't really know."

There are a lot of questions about the earth, such as why it has a magnetic field, and there are many theories about what produces heat in the center of the earth, both of which have to do with the earth's composition, Learned said.

The best place to measure uranium and thorium in the earth's mantle is in the middle of the ocean, he said, above a relatively thin ocean crust.

Eventually, he said, the scientists would like to have a number of deep ocean geoneutrino detectors. They could then start doing tomography of the earth and monitoring nuclear reactors in countries that are hiding bomb-making or testing activities, he said.