Cryogenics

Cryomech at the Coldest Place on Earth

February 25, 2019

The first Amundsen-Scott South Pole Station was built in 1956 by the US federal government. Located at Earth’s southernmost point, the station was the first permanent structure at the coldest place on the globe. Since its construction the station has been continuously inhabited by scientists and researchers from all over the world. Despite several rebuilds, the station has remained in operation for researchers without interruption since it opened. Amundsen-Scott is unique in that it experiences six months of perpetual sun and six months of complete darkness, it sees only one true sunrise and sunset each year.

During the summer season Amundsen-Scott can house up to 200 scientists, researchers, and support staff. However, in the winter only an essential staff of around 50 remain to maintain experiments and the upkeep of the station. Weather conditions during this period make it almost impossible for a plane to reach the station, which is the only way staff can receive supplies during this time. The station must become entirely self-sufficient. This complete isolation and lack of available transport has resulted in several scientists who had to treat themselves to survive life-threatening medical conditions such as cancer and appendicitis. Winter also means that if supplies run out for a scientific experiment, the experiment must be shut down and put on hold until deliveries can resume during the polar spring.

Crates arrive at the South Pole

This need to be self-reliant lead to a phone call to Cryomech. One of the on-station telescope experiments required liquid helium, and if the supply were to run out the experiment would need to be shut down. The South Pole might be one of the coldest places on Earth, but it is still not cold enough to keep helium in a liquid state. Boil-off made running out of helium a real possibility, and the researchers needed a new solution to their problem.

On January 19, 2005, Cryomech’s Brent Zerkle arrived at the South Pole to install the newly developed PT410 (1W @ 4.2 K) in one of the stations 1,000-gallon liquid helium dewars. He also provided training to the staff on how to use and maintain their new coldhead. After the success of the first installation, several more PT410s were installed in subsequent seasons. The goal of installation was to create a zero-boil-off environment, so the station would be able to operate the full nine months of their winter season without running out of liquid helium. The new equipment solved the boil-off problem and reliably kept the research going.

Brent Zerkle at the South Pole

In 2013 station staff were able to adapt new coldhead technology directly into the telescopes, making the need for liquid helium obsolete. Since the PT410s were still in perfect working order, they were transferred to the Cosmic Microwave Background program. With slight modifications they worked perfectly in the new receivers. They are still in working order today!

Science on the station isn’t always pretty, but all that really matters is that it works!