What’s a winterover?

If you’ve been watching our website, you might see weekly reports showing up regularly. Photos of dazzling auroras, indoor station photos, mid-winter party images…where do these all come from?

They are the products of the current IceCube winterovers, Sven Lidstrom and Carlos Pobes. “Winterover?” you may wonder. “What’s a winterover?”

The South Pole has two seasons: summer and winter. The summer is a relatively short period, from September to March, when the sun is up 24 hours a day. The other seven months, well, make up the dark South Pole winter. The people who spend the winter at the Pole are known as winterovers. And here’s the kicker. South Pole winterovers are essentially stranded at the Amundsen-Scott South Pole Station from the time the last plane flies out in mid-February until the next plane lands in early November.

That’s almost eight months without fresh food, without medical supplies, and with the same 40 or 50 people. This skeleton crew of winterovers stays through the dark months to keep the station running and maintain and operate science projects.

The fact that planes can’t fly in or out has less to do with the dark and more to do with temperature. During the South Pole, or austral, summer, temperatures typically hover between -25 and -45 degrees Celsius (-13 to -49 Fahrenheit). During the winter months, high temps are around -59 C (-67 F) with lows at -75 C (-103 F). Record lows get down to -82 C (-116 F) with June and July typically being the coldest.

South Pole temperature screenshot courtesy of IceCuber Sven Lidstrom.

At those kinds of low temperatures, jet fuel will start to gel. The hydrocarbons in aviation fuel start to freeze at different rates, turning the fuel from liquid to a waxy slush. Jet engines require pure liquid fuel; anything else will cause reduction in engine function. The thicker the fuel becomes, the more likely the engine will stop all together. Not a great prospect for a machine flying at high speed thousands of meters above a frozen continent.

Chevron recommends that, to avoid frozen hydrocarbons, the freezing point of aviation fuel be less than -58 C (-72 F). While some of the South Pole winter temps might be within those parameters, you have to remember that the planes are flying thousands of meters above the surface of the ice, reducing temperatures by another 20 C (36 F).

In addition to the risk of the fuel turning into slush, Antarctica is known for volatile weather. Even in the summer months, it’s common for a plane to “boomerang,” or turn around mid flight to return to the take-off location. Pilots cannot anticipate weather patterns well enough to guarantee a flight will make it to its destination, and if the skies look bad, they’ll turn the plane around.

The combination of cold and darkness makes flying a plane to the South Pole in the winter a dangerous prospect. So dangerous that they don’t attempt it. In some extreme cases during the transition months (September or March), flight crews have airdropped medical equipment, but for the most part winterovers are resigned to a winter alone.

Although it sounds like a long, lonely prospect, the winter crew plans activities to keep themselves busy, including celebrations, concerts, movie nights, and more. Right now, the winterovers are enjoying seeing the slow sunrise over the horizon.

If you have a question for the IceCube winterovers, submit it via our contact form at http://icecube.wisc.edu/contact

Sven Lidstrom (seen in the photo) and fellow Polie Jay Studer (photographer) spent a lot of time outside to catch this shot. Lidstrom explains, “Yes, it finally worked out really well. I have been trying to get this picture for a long time. I have some other ones but nothing as good. I was getting really cold, it was -103 F, and we had already been out for too long taking photos and everyone else was heading back. You can see I’m covering my chest, got some frostbite there. I see it as a sacrifice for science.”