South Pole Station makes the most of liquid helium supply

Image: A 4,000-gallon helium dewar is unloaded from an LC-130 at the South Pole Station. Such shipments may soon cease as experiments move away from using liquid helium to cool telescope sensors. 

Photo Credit: Paul Sullivan

Helium, it's not just good for party balloons.

At one of the coldest places on the planet -- where the temperature bolts down to minus 100 degrees Fahrenheit during the winter months -- liquid helium has been used to super-cool special telescopes designed to peer into the mysteries of the early universe.

However, the use of bulk liquid helium may also become a thing of the past, as the astrophysical experiments at the South Pole Station complete a conversion to a Cryocooler technology that cools telescope sensors to a temperature just above that of outer space by using and recapturing helium gas.

Helium is a limited resource that promises to become even scarcer and more expensive in the future. A bipartisan bill being considered in the U.S.

Senate this year would help conserve the nation's helium reserves -- locked up underground in a natural geological formation near Amarillo, Texas -- and give priority to federally funded researchers in times of shortage.

The South Pole Station has done its part over the last decade or so to stretch out the nation's helium supply, which is used in everything from the manufacture of fiber optics and microchips to cooling the superconducting magnets used in MRI machines.

The zero boil-off system now at the South Pole ensures that almost no helium is lost to the atmosphere.

Water, of course, has a boiling point of 100 degrees Celsius, transitioning from a liquid to a gas. Helium also has a boiling point, but a wee bit lower -- minus 269C.

On the Kelvin scale, that's about 4.2 degrees above absolute zero, the temperature at which all molecular motion stops. The temperature of outer space is about 3 Kelvin.

The telescopes at the South Pole do not operate in the visible light spectrum, but instead measure microwave radiation.

The telescope sensors use superconductive materials that must be cooled down to 250 milliKelvin, just a quarter of a degree above absolute zero, to study the cosmic microwave background, often described as an afterglow of the Big Bang when the universe burst into existence.

Liquid helium has been an integral part of cryogenic techniques since astrophysical experiments began at the South Pole in the 1980s, according to Paul Sullivan, South Pole Station manager of science support.

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