The South Pole is the most inhospitable place on Earth—yet, each year, around 50 brave scientists and staff endure the winter there. Outside temperatures approach minus 120 degrees Fahrenheit in constant darkness.

And they better hope nothing goes wrong. Because no one can come to help them.

The South Pole is 800 miles from the nearest human contact. That’s farther than the International Space Station, which orbits less than 400 miles above Earth.

From research bases on the Antarctic coast, it takes planes 5 to 8 hours to fly to the South Pole. But it’s so cold in winter that jet fuel turns to slush, meaning no flights can come or go.

An over-land caravan of snow tractors in the summer takes 40 days.

The sun is up in summer for more than 4,000 hours, one six-month-long day. At that time, the South Pole research station has its highest population, 200 scientists and staff. They study solar spots and atmospheric ozone, cosmic rays and neutrinos.

Low temperatures still average negative 20 degrees Fahrenheit.

In the fall, the sun nears the horizon for six weeks of dusk. Then it sets and is gone for three months for that seemingly endless night that is Antarctic winter.

It takes a special person to endure the isolation, darkness, danger and lethal cold.