Back in the 1980s, Francis Halzen presented a radical idea for a new kind of space observatory. He realised that the Antarctic ice could be ideal for discovering more about the universe. In 1988, he presented his idea in a paper titled ‘High Energy Neutrino Detection in Polar Ice', along with co-author, John G. Learned. Instead of looking up at the sky with traditional glass lenses, he proposed looking down into the Antarctic ice to detect high-energy cosmic neutrinos. ‘Fig 1’ pictured here is the first diagram that was presented to illustrate how the telescope would function. 1. The earth as a giant filter (top): Neutrinos are ghost-like cosmic particles that pass right through almost anything. They travel from distant cosmic sources, enter the Earth, and shoot toward the South Pole. By looking downward, the telescope uses our entire planet to block out messy background radiation. This ensures that any particle traveling straight up from underground must be a neutrino. 2. The ice telescope (bottom): Buried deep beneath the South Pole is the actual detector. While the surface ice is bubbly, the extreme pressure deep down makes the ice crystal clear. When a rare neutrino finally crashes into an atom in this deep ice, it creates a secondary particle called a muon. As this muon shoots upward, it creates a faint flash of light (which is called the Cerenkov radiation). Scientists drill deep holes into this clear ice and fill them with highly sensitive light sensors to capture these flashes and trace exactly where the neutrino came from. Halzen quickly convinced many others of his idea’s potential and, in 1992, a group of tenacious researchers and engineers made the first attempts to lower light sensors into the glacier at the South Pole. This later developed to what is now called the IceCube Neutrino Observatory. It detects high energy neutrinos from deep space, giving insight into the extreme environments from which they originate to unravel new secrets of the universe. Francis Halzen was awarded the Nobel Prize in Physics in 2026. Read the paper here: bit.ly/47rflly Diagram: Francis Halzen and John G. Learned