BioEd Online

The US National Science Foundation (NSF) has chosen an abandoned gold mine in South Dakota as the preferred site for a massive underground laboratory.

The Homestake Mine, near the town of Lead, beat several competing sites to become the leading candidate for the Deep Underground Science and Engineering Laboratory, a proposed $500-million facility. The underground lab could be used to study physics, geology and microbiology 2,250 metres beneath Earth's surface.

"In the end it was a very clear decision," says Charles Baltay, a physicist at Yale University in New Haven, Connecticut, who led the NSF's 22-member review panel. Baltay says the Homestake proposal excelled in almost every aspect of the competition.

Always a winner

Homestake was first suggested as a location for an underground facility in 2001, and quickly won the backing of powerful politicians such as South Dakota senator Tom Daschle, then Democratic minority leader.

But political and environmental concerns slowed the process, and in 2003, the mine's owner, Barrick Gold, allowed the mine to begin flooding with water.

Meanwhile, the NSF analysed multiple sites. But some researchers criticized the review for being too hasty in choosing Homestake and a second facility, the Henderson Mine in Empire, Colorado, as the best candidates. The process was reopened last July, to include two more proposals from Washington and Minnesota.

The final decision is no surprise, says Marvin Marshak, a physicist from the University of Minnesota in Minneapolis who led one of the proposals. "There have been several other selections and each time Homestake has won," he says. "As a scientist, I'm trained to see patterns."

The latest review seemed fair, says Chang Kee Jung, a physicist at the State University of New York, Stony Brook, who led the Henderson proposal. "I think the NSF did a good job," he says. Wick Haxton, a physicist at the University of Washington in Seattle and leader of that state's proposal, agrees: "I feel pretty good about the process," he says.

Homestake may have won in part because the state of South Dakota has committed nearly $46 million to the project, with South Dakota billionaire T. Denny Sanford contributing another $70 million.

Exotic life

The Homestake site is valuable because the rock above it can shield experiments searching for extremely rare events.

In particular, many scientists are seeking a kind of decay of two neutrons called neutrinoless double-beta decay. Spotting such an event would provide fundamental insights into the standard model of particle physics. It might also help to explain why there is more matter than antimatter in the Universe.

The site can also be used to study exotic life living deep within rock, says Tullis Onstott, a geomicrobiologist at Princeton University in New Jersey. "Most of these organisms don't depend on oxygen to survive," Onstott says. What nutrients they do need, and how they get them, could provide clues to how life began, he adds.

The decision does not ensure the laboratory will be built. The NSF has committed $15 million over the next three years for a full-scale design of the lab. A separate board will ultimately have to sign-off on that design before full-scale construction can begin.

But the money from the state and Sanford should pay for construction of an interim lab at nearly 1,500 metres below the surface, says Kevin Lesko, a physicist from Lawrence Berkeley Laboratory in California, who led the winning collaboration. Equipment in the mine is now being recertified and the site may be open to scientists as early as September. "I'm very excited," says Lesko.