The final flight out of the South Pole was Friday, February 13—the last chance to leave until mid-November. Those 40 or so people staying the winter will have no way out of Antarctica for around nine months. They won’t even be able to venture more than a mile or two off the base, because all the facilities are in a condensed area, and there's no point in sightseeing during the four months of darkness and two more of twilight.

The Amundsen-Scott South Pole Station is the southern-most of the three U.S. research stations down in Earth’s basement. It is located about a hundred meters from the pole itself. It houses around 150 people during the summer and 50 during the winter. The other stations are McMurdo Station, located on Ross Island, and Palmer Station, on Anvers Island. McMurdo is the most populous of the bunch, with 800 to 900 people residing there in the summer and nearly 150 during the winter. Winter on Antarctica’s Ross Island is slightly shorter than at the South Pole. This winter, planes will fly intermittently out of McMurdo, where winter begins on February 28, and the station’s summer crowd arrives on October 1.

The U.S. Antarctic Program doesn't fly over Antarctica during the winter, even between bases, because temperatures get below -50 degrees Fahrenheit, the point at which gasoline freezes. In the depths of winter, around the beginning of July, temperatures can drop below -100 degrees Farenheit. Compounding the cold is the altitude—the South Pole station is nearly 10,000 feet above sea level. In such conditions, even breathing can be painful. Many who attempt to join the 300 Club—a group that endures a 300-degree temperature change by heating themselves in a 200-degree sauna and then streaking naked to the pole and back in sub-negative-100-degree weather—will often wear a scarf, if nothing else.

One of the most disorienting parts of living at the pole is that the sun neither rises nor sets. If a full day is the time between two sunrises, a full day in the South Pole lasts approximately 8,760 hours (24 hours multiplied by 365). This is because, at the pole, the sun rises just once a year and sets many months later. During the summer there are 24 hours of sunlight, and, during the winter, 24 hours of darkness.

There are significant health concerns that result from extended periods without sunlight. The most notable health effect is depression. Those with seasonal affective disorder might be particularly vulnerable. As a result, according to Peter West, who manages Antarctica-related media for the National Science Foundation, there is an intensive screening process for prospective workers. The tests for physical and mental fitness are much like those given to astronauts. The best way to avoid emergencies, West says, is to reduce risk.

This screening is generally successful. Bill Coughran, an area manager who spent several winters in the South Pole and is there right now, says, “We are naturally very safety-conscious. The most common accident would be back strain or the odd slip.” Polly Penhale, who is in charge of health and safety for the U.S. stations in the Antarctic, echoes, “The most common accidents are minor ones. Strains, muscle pulls, getting cut in the kitchen. Summer and winter aren’t all that different.”

When an emergency does happen, there are a few nurses and general physicians at the base. However, there aren’t any specialists. For psychological treatment and physical ailments requiring specialized help, the Antarctic bases have a partnership with the University of Texas Medical School. “There’s a rigorous telemedical program,” Penhale explains.

Still, no matter how mentally fit the person, lack of sunlight causes a deficiency in Vitamin D. Without enough sunlight—the amount needed depends on the color of a person's skin, and how much is exposed—it’s common to become sick and depressed. When asked whether stations typically have a sunroom for those who stay the winter, West replied, “Individuals may have their own lamps. But there is no program-wide room with Vitamin D lamps.”

The people I spoke with didn’t seem overly concerned about any instances of depression that might result from Vitamin D deficiency. Katy Jensen, a risk and opportunity manager who has wintered at the South Pole, says, “I think each of us experienced occasional periods of homesickness or feeling blue, but we tried to recognize that it was normal, and temporary, and we were surrounded by good friends who could help each other get through it.” Coughran takes a more come-as-it-may stance, “Naturally months of isolation have their ups and downs.”

Peter Rejcek, who wintered as a “carpenter helper” in 2004 and is now an editor for The Antarctic Sun, contends that winters are not as lonely as they might seem. “You’re living and working in pretty close quarters, so the problem is more about finding personal space than being lonely. You’re working long hours, so by the end of the winter, you’re pretty exhausted, even if your job isn’t that physical.”

Most people who stay the winter do it to keep the bases operating. A year-round maintenance staff ensures that drainage, electricity, and other essential operations continue to run smoothly. Rejcek says, “There is a core group of positions that need to be filled each year, such as power plant mechanic or cook. My winter involved major construction of the new research station, so there was a large construction crew on site. Major upgrades, installations, and maintenance for experiments are scheduled for the summer.” Most of the scientists leave, Rejcek says, but each experiment, such as the IceCube Neutrino Observatory, has a winter-overseer to troubleshoot any problems, and a few research assistants stay to maintain autonomous experiments.

Winterers often work six days a week of double-digit hours. But for their downtime, the base has a gym, crafts room, library, and hydroponic greenhouse. “People are always volunteering to teach different classes, like yoga, dance, or even a foreign language,” Rejcek says. “There’s usually a band or two that will form and play shows during the winter.” He explained that there are no bars at the South Pole, but there used to be a drinking spot called Club 90 South.

Jensen found an even better way to pass the hours. “After sunset in March, there’s about a month of gradually darkening twilight, so every day you can walk outside and see more stars than you saw the day before. The moon is up above the horizon for two weeks at a time, so you swear you can watch it change phases. And the auroras!”