Chasing a Cosmic Engine

After 100 years, energetic space particles continue to pose a perplexing mystery

It was August 7, 1912, and Victor Hess was about to solve a mystery.

A helium-filled balloon launched from McMurdo Station in Antarctica in 2004 carried the Cosmic Ray Energetics and Mass experiment on a 42-day journey. NASA
A century ago, Victor Hess (center) determined that energetic particles in the atmosphere, called cosmic rays, come from outer space.