An Iridium flare flashes above the South Pole Telescope. (These flares occur when the sun reflects off of the Iridium satellites used for remote communication in Antarctica.)

NASA’s Ultra Long Duration Balloon. Once released, these balloons expand to the size of a stadium.

These light sensors (Digital Optical Modules, or DOMs) are placed deep within the ice in order to detect the blue light emitted when neutrino particles collide with atoms in the ice.

Ask an astronomer to describe the perfect place to put a telescope, and here’s what she’ll tell you: Make it cold, make it dark, make it high-altitude, and make it remote. In short, make it Antarctica.

All light-based astronomy is vulnerable to interference from the atmosphere, the same jittery effect that makes stars twinkle. Much like trying to see the bottom of a swimming pool, observing space through the moving air masses in our atmosphere causes images to wiggle and warp.

The very attributes that make Antarctica inhospitable to life make it ideal for astronomy. The high altitude means there’s less atmosphere to look through. The cold, dry air makes for minimal water vapor and less atmospheric emission of infrared light, both of which interfere with observations. Best of all, 24-hour darkness in winter means no daily temperature oscillations, reducing air currents.

The South Pole Telescope, located at the Amundsen-Scott Station near the South Pole, takes advantage of these clear skies to search for evidence of dark energy amid galaxy clusters. Dark energy is theorized to be a form of energy that is pushing everything in the universe apart.

To further reduce atmospheric interference, some astronomers use balloons to bring their instruments 35,000 feet into the air. Inexpensive compared to satellite-based astronomy, balloon-borne astronomy is ideally suited to Antarctica, where circumpolar winds high in the stratosphere carry balloons steadily and predictably around the pole.

One of the biggest astronomical efforts in Antarctica is actually taking place under the ice. IceCube is an array of ultra-sensitive light detectors buried a mile deep into the Antarctic ice sheet. These detectors can spot the passage of high-energy neutrinos, particles created by the most violent events in the universe, allowing astronomers to see impossibly distant cosmic events by detecting the neutrinos they create.

ICE-T on Dome C
An international team of astronomers have their sites set on another location in Antarctica—a formidably remote location known as Dome C—for construction of a new telescope. High on the Antarctic plateau, Dome C boasts atmospheric conditions that are even calmer—and thereby clearer—than those at the South Pole. “A telescope there would perform as well as a much larger one anywhere else on Earth,” says Will Saunders, astronomer at the Anglo-Australian Observatory. “It’s nearly as good as being in space.” The telescope in the works for Dome C, called ICE-T, will search for exoplanets, earth-like planets in other solar systems.

Jeff McMahon, Kathryn Schaffer, and Tom Crawford are all postdoctoral scientists at the University of Chicago and members of the South Pole Telescope Team. In the Antarctic summer season of 2006/7, the team raced to assemble a 30-foot (10-m) telescope at the South Pole, and in the 2007/8 season they upgraded and installed new equipment before running the telescope through its paces to collect more data about the mysterious cosmological force of dark energy.

The discovery of dark energy in 1999 stunned the scientific community because it suggests that the universe is being thrown apart by a repulsive force rather than drawn together by gravity as previous theories have proposed. By gathering data from large galaxy clusters in deep space, the South Pole Telescope will help astronomers learn more about when dark energy first developed in the universe and how it gained strength to become a dominant force today. Jeff McMahon was the first to arrive at the South Pole; his job was smoothing out the telescope mirror by tightening thousands of screws holding it together. Kathryn arrived in November 2007, and installed a piece of equipment called a Fourier Transform Spectrometer (FTS) that calibrates each of the 1000 detectors on the telescope’s sensitive camera. She also analyzed data gathered by the SPT. Tom was the cleanup man, adding an extra hand to whatever task was necessary at the end of the summer season in late January and early February 2008. Learn more about the team’s work through their dispatches, which are archived on this site.

An aerial view of the South Pole with the South Pole Station to the left of the runway and IceCube to the right.

A string of 60 light detectors called “DOMs” (digital optical modules) are lowered deep into the Antarctic ice sheet.

DOMs under construction. The board stacks have been mounted and will be sealed inside the complete sphere.

The IceCube project is designed to detect high-energy neutrinos, particles created by the most violent events in the universe: black holes, gamma ray bursts, and supernovas. The detector serves as a deep-space telescope, allowing scientists to see impossibly distant cosmic events by detecting the neutrinos they generate.

IceCube consists of an array of ultrasensitive light detectors buried roughly a mile deep into the Antarctic ice sheet. To build it, researchers drill into the ice sheet with a hot water drill, then sink a vertical string of light detectors—think of an oversized string of Christmas lights—into the water-filled hole before it freezes over again.

Why put a neutrino detector under ice? The polar ice sheet supplies, naturally, the main ingredient needed for a neutrino detector: a large space that is totally dark and totally transparent.

Though neutrinos are zooming around us all the time—a million billion of them stream through your body each second—they can only be detected when they crash directly into the nucleus of an atom. The collision creates a faint glimmer of blue light, called Cherenkov radiation, which passes easily through the transparent ice to be “seen” by one or more of IceCube’s 4,800 light detectors. By tracking the path of these incoming neutrinos, scientists get an unprecedented view: a neutrino-based picture of the universe.

The IceCube Laboratory (ICL).

The IceCube array shown in relation to the drill camp and the bedrock beneath.