For the first time, scientists have successfully measured a global electric field on Earth that has long been theorized but never confirmed—until now.
This discovery was made possible through observations from a NASA suborbital rocket, marking a significant breakthrough in understanding the Earth’s atmosphere and how it interacts with space.
This electric field, known as the ambipolar electric field, was first proposed over 60 years ago. Scientists believed it played a crucial role in how particles from Earth’s atmosphere escape into space, particularly at the North and South Poles.
The new measurements, gathered during NASA’s Endurance mission, have confirmed the existence of this electric field and revealed its strength.
These findings help explain the phenomenon known as the “polar wind,” where particles are drawn out of the atmosphere into space.
Understanding how Earth’s atmosphere changes and evolves over time not only provides insight into our planet’s history but also offers clues about other planets and their potential to support life.
The research, led by Glyn Collinson from NASA’s Goddard Space Flight Center, was published in the journal Nature.
Since the 1960s, spacecraft have detected particles flowing from Earth’s atmosphere into space, particularly over the poles. Scientists predicted this outflow, called the “polar wind,” but were puzzled by its characteristics.
The particles were cold and unheated, yet they traveled at supersonic speeds. This led scientists to suspect that an unknown electric field might be responsible for pulling these particles out of the atmosphere.
However, detecting this electric field was a major challenge. It was thought to be extremely weak, with its effects only noticeable over vast distances.
For decades, the technology needed to measure it simply didn’t exist. In 2016, Collinson and his team set out to develop a new instrument capable of detecting this elusive field.
To measure the ambipolar electric field, the team needed to launch a suborbital rocket from the Arctic, a location where the polar wind could be directly observed.
The mission, named Endurance after the ship that carried explorer Ernest Shackleton on his famous Antarctic voyage, was launched from Svalbard, Norway—one of the northernmost rocket ranges in the world.
On May 11, 2022, the Endurance rocket reached an altitude of 477 miles, collecting data across a 322-mile range before splashing down in the Greenland Sea. During this flight, Endurance measured a tiny change in electric potential—just 0.55 volts.
This small measurement, equivalent to the power of a watch battery, was enough to explain the polar wind. Hydrogen ions, the most common particles in the polar wind, experience a force from this electric field that is over 10 times stronger than gravity, allowing them to escape into space at supersonic speeds.
The electric field also affects heavier particles like oxygen ions, making them lighter and enabling them to rise higher into the atmosphere. This discovery showed that the ambipolar field significantly increases the “scale height” of the ionosphere, meaning this layer of the atmosphere remains denser at higher altitudes than it would without the field.
The discovery of Earth’s ambipolar electric field opens up new possibilities for understanding how our atmosphere has evolved over time.
This field, now recognized as a fundamental force of our planet alongside gravity and magnetism, may have played a continuous role in shaping our atmosphere.
Moreover, because the ambipolar field is generated by the internal dynamics of an atmosphere, scientists believe that similar fields likely exist on other planets, including Venus and Mars.
“Any planet with an atmosphere should have an ambipolar field,” said Collinson. “Now that we’ve finally measured it, we can begin learning how it’s shaped our planet as well as others over time.”
This groundbreaking discovery marks a significant step forward in our understanding of Earth’s atmosphere and its interaction with space, paving the way for future explorations of other planets in our solar system.
