More than six decades ago, scientists first became aware of a mysterious phenomenon in Earth’s atmosphere. Hypothesized to be a fundamental driver of atmospheric dynamics, now for the first time, a team of rocket scientists at NASA says they have finally succeeded in detecting it.
The breakthrough discovery, made as a part of NASA’s Endurance mission, has now confirmed the existence of Earth’s ambipolar electric field, which reveals a planetary-scale force that governs phenomena known as atmospheric escape, and sheds new light on the evolution of our planet.
The ambipolar electric field was first theorized to exist more than half a century ago, playing a crucial role in planetary phenomena along similar lines to gravity and the Earth’s magnetic fields. The Endurance mission’s new findings help to demonstrate the long-sought electric field’s influence on what scientists call the “polar wind,” which describes an ongoing outflow of charged particles that empty into space above Earth’s poles.
The discovery will provide researchers with new approaches toward understanding atmospheric processes that occur on Earth, as well as on other planets.
Discovery in Earth’s High Atmosphere
The long mysterious ambipolar electric field, which is a weak but also a fundamental force governing behavior of the planet’s upper atmosphere, was detected by NASA’s Endurance mission using a special suborbital rocket launched from a location in the Arctic.
Designed to measure Earth’s global electric potential, which involves the degree to which Earth’s electric field influences electrically charged particles in the air, the Endurance mission’s rocket was successful in detecting and measuring this extremely weak electric field.
By confirming the field’s existence, the NASA research team believes the discovery will help to provide new information on how weak electrical phenomena in Earth’s atmosphere shape the ionosphere, the radio wave-reflective upper region of the atmosphere possessing an abundance of charged particles.
What is the Ambipolar Electric Field?
At high altitudes where atmospheric particles become ionized, the mysterious ambipolar electric field is produced as negatively charged electrons and positively charged ions naturally balance out. The result is a separation of charges resulting from this balance which cancels out some of the effects of gravity, which effectively propels charged particles high enough into the atmosphere that some of them escape into space.
The effect of this phenomenon is most pronounced at Earth’s poles, resulting from what researchers call a “polar wind” that carries particles away from our planet’s atmosphere.
The Endurance mission team employed a unique series of instruments that allowed the rocket they launched to record changes in electric potential in the atmosphere as low as .55 volts. Although this may seem miniscule, discerning such subtle changes across a range of altitudes is enough to explain the movement of hydrogen ions, the most abundant particles in the polar wind, which are propelled to supersonic speeds.
According to the Endurance team’s findings, heavier particles in the atmosphere, which include oxygen ions, are also impacted by the effects of the ambipolar electric field, which showcases the broad influence it has on atmospheric escape.
Fundamentally, the new findings by NASA’s Endurance mission help to provide deeper insights into the planet’s atmospheric evolution, which could apply under the right conditions on other planets too, which include nearby planetary neighbors Mars and Venus.
The ambipolar electric field has likely been a continuous force in helping to shape Earth’s atmosphere over time, and if similar phenomena exist in the atmospheres of nearby planets, the new insights could help to explain their evolution over long periods, potentially spanning billions of years.
“Any planet with an atmosphere should have an ambipolar field,” said Glen Colinson, principal investigator of Endurance at NASA’s Goddard Space Flight Center.
“Now that we’ve finally measured it, we can begin learning how it’s shaped our planet as well as others over time.”
Colinson is the lead author of a new paper detailing the team’s findings, which was published on Wednesday, Aug. 28, 2024, in the journal Nature.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email at micah@thedebrief.org. Follow his work at micahhanks.com and on X: @MicahHanks.