Even though the study of Lake Bonney promised to be an intriguing experiment, Alabama-bred Ward did not pine for Antarctica. "I never had any intention of being that cold," she says. When asked to join an Antarctic expedition in 1991, Ward agreed to go only after being prodded by her graduate student, Mary Voytek. Voytek had been to Antarctica before, as part of a different research effort. She and Ward joined 1992 and 1994 expeditions to the coldest place on earth.

The north and south poles receive the same paltry dose of sunshine, but Antarctica is still far colder than its northern cousin. On average, Antarctica is three times higher than any other continent, and since temperature drops with elevation, Antarctica has earned its nickname, "the freezer."

Ward didn't warm to it. She even met the first hardship before she arrived. A U.S. Navy cargo plane carried scientists from New Zealand to Antarctica's McMurdo Station in an eight-hour flight. "There's no bathroom," Ward says. "They have a bucket, but you're just sitting there with all these Navy guys." In two round trips, Ward has yet to urinate in transit.

The situation didn't improve much at McMurdo Station, a spartan outpost. It sits next to Robert Falcon Scott's wooden hut, frozen since 1911, when Scott died making his return from the south pole. "McMurdo isn't a very nice place," says Voytek. "It has a disproportionate number of men and an industrial sort of hustle bustle, with the constant noise of machinery." The facility balloons from 150 permanent staff members to more than 1,000 people in the less severe months from November to February. Many of those who arrive for Antarctica's version of summer are scientists. The permanent support staff derisively call the scientists "beakers," in reference to the laboratory flasks used to hold and analyze chemicals. "You get so you like a tent more than you do McMurdo," Ward says.

Tent life gave her beautiful views and beastly weather. Navy helicopter pilots flew Ward and her scientific colleagues from McMurdo to the shore of Lake Bonney. Photographs from the expeditions show tents and equipment boxes sitting on a lifeless terrain of brown sand. Some of the nearby glaciers wear rust-colored streaks after centuries of gouging metal deposits from the ground, and others glow electric blue. Even in the warmer months, winds dive over these glaciers to destroy experiments and send tents tumbling. Microscopic organisms -- plankton and bacteria -- are the only native life in the area, and they lie deep under the ice.

"My first trip to Antarctica was horrible," Ward says. A mysterious flu-like illness struck Ward in her first two weeks by the lake. Her worried companions urged her to return to McMurdo Station, but she decided to take her chances in the tent.

Ward recovered and even tended John Priscu when he suffered a similar illness later that month. "She made me some turkey soup," Priscu says. "Even though she's a vegetarian."

She also helped run the experiments. The idea of studying Lake Bonney is simple: drill a hole, collect water samples from various depths, and take the bottles home to a comfortable laboratory where no one risks freezing to death. However, the 12 feet of ice, the extreme cold, and the sand-bearing wind complicated each task. After the scientists had created a hole about three feet across, they put together an aluminum and canvas hut around the ice shaft and prepared for their scientific ice-fishing.

After two months working on the ice, Ward flew back to her Santa Cruz laboratories with dozens of gallons of Lake Bonney. By carefully analyzing the DNA of the lake's bacteria collected in 1992 and 1994, Ward uncovered surprising lake tenants. Many of the bacteria in Lake Bonney were "denitrifiers." Bacteria usually take in oxygen to run their biological engines, but when oxygen is in short supply, denitrifying bacteria can switch fuels. "These bacteria wear denitrification like a necklace," Ward says. "They can put it on or take it off as the situation requires."

Despite the east lobe's army of denitrifying bacteria, Ward found that it still contained much higher concentrations of nitrogen-based chemicals than the west lobe. When exposed to so much nitrogen, denitrifying bacteria normally treat it as a hungry person would treat a plate of warm biscuits. "They're just not doing their job in the east lobe," Ward says. "Maybe they're pickled." She's only half kidding. Some biologists have suggested that the lake is so cold that the bacteria sit dazed, breathing only sporadically, but the west lobe's bacteria busily process nitrogen in water that is even marginally colder than the east lobe. So why has one neighborhood fallen on hard times? "We really have no idea," Ward says.

The answer that sits in Lake Bonney may well apply to ocean-sized questions. Ward has identified patches of denitrifying bacteria in the world's seas, and she thinks these bacteria might be able to nullify the harmful effects of nitrogen-fertilizer pollution. However, scientists don't yet understand the series of events that can lead these bacteria to start breathing nitrogen instead of oxygen. Ward hopes to discover a trace mineral or metallic element in the east lobe that has somehow convinced the bacteria that they don't want nitrogen.

"I'm really excited about the project," she says. "And I want to get back to studying the lake." Her scientific drive opposes her gut reaction to Antarctica itself. Though Ward says she loved her various ocean voyages, Antarctic colleagues say that she did not relish the demanding camping experience. "I don't live or die to go there," Ward says, but she's been there twice and will go again.

"I'm sure its due to my parents," she says. "I just realize more and more that they're an overwhelming influence for good and bad. A lot of my drive comes from my mother." Ward's parents are southern Baptists, and she says her mother worked to stave off a deep puritanical guilt. High expectations for Charlotte's daughter were a natural extension. If a scientist needs to postpone sleep until the lab electronics are working, so be it, and if the important questions point to the bottom of the planet, that's where she goes.

In the south pole's warmer season of 1999, Ward and a few colleagues plan to spend another eight weeks testing Lake Bonney. Reinforcing the geology part of her biogeochemist reputation, Ward will search for minerals, trace metals, or anything else that might cause bacteria to lose their appetite for nitrogen. Once again, she will board the cargo plane, visit McMurdo Station with the other "beakers," and take a helicopter ride to Lake Bonney. She will endure the climate, living in a tent for more than a month. She will lean into the wind, cross the ice, and drill for an answer.