NASA’s Endurance Mission Measures Earth’s Ambipolar Electric Field for First Time
NASA Space Technology First hypothesized more than 60 years ago, the ambipolar electric field is a key driver of the polar wind, a steady outflow of charged particles into space that occurs above Earth’s poles. This electric field lifts charged particles in our upper atmosphere to greater heights than they would otherwise reach and may have shaped our planet’s evolution in ways yet to be explored.Collinson et al. report the existence of a +0.55 ± 0.09 V electric potential drop between 250 km and 768 km from a planetary electrostatic field generated exclusively by the outward pressure of ionospheric electrons; they experimentally demonstrate that the ambipolar field of Earth controls the structure of the polar ionosphere, boosting the scale height by 271%. Image credit: NASA.Since the 1960s, spacecraft flying over Earth’s poles have detected a stream of particles flowing from...
