In a groundbreaking discovery, scientists have successfully detected and measured an invisible electric field that surrounds Earth, known as the ambipolar field.
First theorized over six decades ago, this elusive field has now been confirmed, marking a significant leap forward in our understanding of Earth's atmospheric dynamics.
The research, led by Glyn Collinson at NASA's Goddard Space Flight Center, could have far-reaching implications for the study of planetary atmospheres and other celestial bodies.
The ambipolar field is located around 250 kilometers (155 miles) above Earth's surface in the ionosphere — a region of the atmosphere ionized by solar and ultraviolet radiation. This field forms due to the interaction between negatively charged electrons and positively charged ions.
When ultraviolet rays ionize atmospheric atoms, they create a mix of free electrons and ions. The ambipolar field works to stabilize these particles, with electrons attempting to escape into space and ions pulling them back toward Earth, creating a balancing force.
The ambipolar field was detected during a mission by the Endurance rocket, which launched in May 2022. The rocket reached an altitude of 768 kilometers (477 miles) before returning to Earth with critical data. The mission aimed to measure the subtle electric potential changes associated with the ambipolar field.
Although the field's strength was weak - registering only a 0.55-volt change, similar to the charge of a watch battery - this slight variation was enough to confirm the field's existence and its influence on the polar wind.
The discovery of the ambipolar field sheds light on its crucial role in regulating Earth's atmospheric density and composition. It influences the altitude at which ions escape into space, impacting the overall structure of the atmosphere. Understanding this field provides new insights into how Earth's atmosphere maintains charge neutrality and how particles are transported away from the planet.
The ambipolar field also affects the polar wind, a stream of particles flowing from Earth's atmosphere, particularly at the poles.
While this discovery is a major milestone, it opens the door to many new research questions. Scientists are now eager to explore how long this field has existed, its role in atmospheric evolution, and its potential impact on life on Earth. Glyn Collinson emphasizes that measuring the ambipolar field allows researchers to ask new questions about Earth's atmospheric processes and planetary science more broadly.
This breakthrough paves the way for deeper exploration into the fundamental mechanisms that govern Earth's atmosphere. It also holds promise for applying these insights to other planets with similar atmospheric conditions.