October 27, 1916–February 6, 2001

BY KINSEY A. ANDERSON

JOHN RANDOLPH WINCKLER was a gifted experimental physicist who made major discoveries in solar, magnetospheric, auroral, and atmospheric physics. He designed and built experimental apparatus for flight on balloons, sounding rockets, and Earth-orbiting spacecraft. Some instruments were exquisite in their simplicity, others highly complex. However, all fit the needs of Winckler’s scientific objectives. Early in his research career he ingeniously adapted systems used by the U.S. Navy to detect submarines during World War II to retrieve scientific data from high-altitude research balloons. His first major scientific discovery was to show that electrons with energy in the range of tens to hundreds of kiloelectron volts accompanied bright, active aurora. A few months later with L. E. Peterson he observed and measured an intense and short-lived burst of photons in the energy range of tens to hundreds of kiloelectron volts. The burst was coincident with a bright and active solar flare. This discovery added a new dimension to the study of high-energy particle phenomena occurring on the Sun.

He made many investigations of the geomagnetically trapped energetic particles including “active” experiments.¹ This work required a major technical effort in order to