About 200 scientists are in Washington this weekend to discuss the next steps toward converting the Homestake gold mine into a national underground laboratory, and state officials were there to encourage them.

"We want you to come to South Dakota, and we want you to feel welcome," Gov. Mike Rounds said at the opening session Friday at the National Academy of Sciences.

Sen. John Thune, R-S.D., and Rep. Stephanie Herseth Sandlin, D-S.D., also spoke in support of the project, along with a representative of Sen. Tim Johnson, D-S.D.

But most of the "DUSEL town meeting" is devoted to science and engineering.

In July, the National Science Foundation chose Homestake as the site for a proposed Deep Underground Science and Engineering Laboratory. Now, scientists and engineers are designing the proposed lab. "This meeting this weekend is crucial in putting together the initial suite of experiments," physicist Kevin Lesko of the University of California at Berkeley said.

Berkeley is the lead institution in the Homestake lab proposal, and Lesko heads a team of scientists from around the country.

Deep labs protect experiments from the noise of cosmic radiation, allowing scientists to single out faint evidence of elusive particles and phenomena such as neutrinos, anti-matter and the even more mysterious "dark matter."

Berkeley physicist Bernard Sadoulet, who organized the town meeting, said, "We have to go where it's quiet."

Physicists still can't explain about 95 percent of the mass of the universe, Sadoulet said, or even why there is mass. "This is really a question of the genesis of matter in the universe," he said.

Scientists also got an overview of the nuts-and-bolts project Friday, during a session that was also available to reporters by teleconference.

NSF physics program officer Jon Kotcher said a DUSEL at Homestake could cost $500 million - half of that for construction and half for the initial experiments.

Building the lab would take seven or eight years, Kotcher said, and the earliest construction could begin would be fiscal year 2011. That's because the NSF, the National Science Board, the White House and Congress will have to approve a DUSEL.

The NSF awarded Lesko's team $15 million to create a detailed plan for the lab over the next three years.

Lesko described how a NSF-funded DUSEL would have three underground "campuses" - one just 300 feet underground, another 4,850 feet underground and - most important - a deep campus 7,400 feet underground.

A Homestake DUSEL would be the deepest and maybe the largest underground lab in the world, but it could take a decade or more to build.

In the meantime, Rounds said, South Dakota has raised $116 million to jump-start the process - thanks in part to a $70 million donation from philanthopist T. Denny Sanford.

The South Dakota Science and Technology Authority, which owns the mine, will open a "Sanford" lab at the 4,850-foot level. "We'll be open for science by late next year," Rounds said.

South Dakota can operate the Sanford lab for five years, Rounds said, while waiting for approval of the deeper DUSEL, which he acknowledged might never come. He called it "a calculated risk."

The South Dakota science authority re-entered the mine in July, and crews are slowly working their way down the 5,000-foot Ross Shaft to install pumps to remove the water that has been filling the mine since it was sealed shut in 2003.

Dave Snyder, executive director of the science authority, told scientists Friday that water had risen from the bottom of the mine, 8,000 feet underground, to 4,996 feet underground "as of an hour ago."

If water reaches the 4,850-foot level, South Dakota's plan for a Sanford Laboratory will be more expensive, but Snyder said the water had risen only 4 feet since July 27. He estimated the water would not reach "the 4850" until February, and crews are working double shifts to start pumping before then.

Even if the water reaches the 4850, Rounds said, the Sanford Lab will be built. "We're going to open this facility, but we'll need your support," he told the scientists.

Contact Bill Harlan at 394-8424 or bill.harlan@rapidcityjournal.com