Cranes hoist cargo onto the deck. Power tools scream out. Workers bustle through a maze of passageways. Welcome to the German icebreaker ship RV Polarstern. The huge ship will soon set out for the Arctic.

Polarstern is packed with scientific equipment. Researchers will use it to explore Earth’s frigid far north. “So far we have always been locked out of that region,” says Markus Rex. He will lead the expedition.

Scientists plan to sail the ship into the Arctic Ocean. They will anchor it to a large piece of sea ice. Water will freeze around it. Each year, a huge sheet of white ice covers the North Pole at winter. These scientists are trapping themselves in it . . . on purpose!

Temperatures will drop. Days will get shorter. The scientists will race against time. They will build winter research camps on the ice. They will perform tests impossible at other times of the year.

For what? They hope their sea ice measurements will help predict Arctic weather—and weather farther south. Scientists believe Arctic ice determines temperatures across the Northern Hemisphere.

Dozens of scientists from the United States, China, Russia, and other countries will be on board the Polarstern at any one time. They’ll swap out. Every two months, other icebreakers will bring fresh supplies and a new batch of researchers.

This is a once-in-a-lifetime opportunity. In winter, the scientists on board will be even harder to get to than people on the International Space Station. (The Space Station orbits only around 254 miles high. Other spacecraft can reach it regularly.) Once the water freezes, these scientists will be truly stuck. They’ll be truly alone. Emergency rescue will be almost impossible.

But what if an emergency does happen? They try to prepare now. They even make a fence to put around the ship that will sound an alarm if a polar bear comes near!