NASA Discovers a Long-Sought Global Electric Field on Earth
Unveiling Earth’s Hidden Force: The First Detection of the Ambipolar Electric Field and Its Impact on Our Planet
Key Highlights
- A team of rocket scientists has successfully detected Earth’s ambipolar electric field for the first time. This is a weak, planet-wide electric field, considered as fundamental as Earth’s gravity and magnetic fields.
- First proposed over 60 years ago, this ambipolar electric field is crucial in driving the “polar wind,” a continuous flow of charged particles into space that originates above Earth’s poles.
- This electric field elevates charged particles in our upper atmosphere to greater altitudes, potentially influencing Earth’s evolution in ways still to be explored.
Using data from a NASA suborbital rocket, an international team of scientists has for the first time measured a global electric field thought to be as essential to Earth as its gravity and magnetic fields. Known as the ambipolar electric field, scientists theorized over 60 years ago that it drives the escape of our planet’s atmosphere above the North and South Poles. Measurements from the rocket, part of NASA’s Endurance mission, have confirmed the existence of this ambipolar field, revealing its strength and role in atmospheric escape and broader ionospheric dynamics.
Understanding the complex behavior and evolution of Earth’s atmosphere not only provides insights into our planet’s history but also sheds light on the mysteries of other planets, helping to determine which might be capable of supporting life. The research was published on August 28, 2024, in the journal Nature.
An Electric Field Drawing Particles into Space
Since the late 1960s, spacecraft passing over Earth’s poles have detected a stream of particles escaping from our atmosphere into space. This outflow, predicted by theorists and called the “polar wind,” prompted further research to uncover its causes.
Some atmospheric outflow was expected, as intense, unfiltered sunlight should cause some air particles to escape into space, similar to steam evaporating from boiling water. However, the observed polar wind was more puzzling, as many of the particles within it were cold and showed no signs of being heated, yet they were moving at supersonic speeds.
“Something had to be pulling these particles out of the atmosphere,” said Glyn Collinson, principal investigator of Endurance at NASA’s Goddard Space Flight Center and lead author of the study. Scientists suspected that an undiscovered electric field could be responsible.
This hypothesized electric field, generated at the subatomic level, was expected to be extremely weak, with its effects noticeable only over vast distances. For decades, detecting it was beyond the capabilities of existing technology. In 2016, Collinson and his team began developing a new instrument designed to measure Earth’s ambipolar field.
Launching a Rocket from the Arctic
The team’s instruments and theories were best suited for a suborbital rocket flight launched from the Arctic. Inspired by the ship that carried Ernest Shackleton on his famed 1914 Antarctic expedition, the mission was named Endurance. The team set out for Svalbard, a Norwegian archipelago located just a few hundred miles from the North Pole, which hosts the northernmost rocket range in the world.
“Svalbard is the only rocket range where you can fly through the polar wind and gather the measurements we needed,” said Suzie Imber, a space physicist at the University of Leicester and co-author of the paper.
On May 11, 2022, the Endurance rocket was launched, reaching an altitude of 477.23 miles (768.03 kilometers) and splashing down 19 minutes later in the Greenland Sea. Throughout its 322-mile altitude range, Endurance detected a change in electric potential of just 0.55 volts.
“A half a volt might seem insignificant — it’s about as strong as a watch battery,” Collinson explained. “But it’s precisely the right amount to account for the polar wind.”
Hydrogen ions, the most abundant particles in the polar wind, experience an outward force from this electric field that is 10.6 times stronger than gravity. “That’s more than enough to counteract gravity — in fact, it’s enough to launch them into space at supersonic speeds,” said Alex Glocer, Endurance project scientist at NASA Goddard and co-author of the paper.
Heavier particles also receive a boost. Oxygen ions at the same altitude, influenced by this half-volt field, effectively weigh half as much. Overall, the team found that the ambipolar field increases the ionosphere’s “scale height” by 271%, meaning the ionosphere remains denser at greater altitudes than it would without this field.
“It’s like a conveyor belt, lifting the atmosphere into space,” Collinson added.
Endurance’s discovery has paved the way for further exploration. As a fundamental energy field of our planet, alongside gravity and magnetism, the ambipolar field may have continuously shaped our atmosphere’s evolution in ways we are only beginning to understand. Since it is created by the internal dynamics of an atmosphere, similar electric fields are likely to exist on other planets, such as Venus and Mars.
“Any planet with an atmosphere should have an ambipolar field,” Collinson said. “Now that we’ve finally measured it, we can start learning how it has influenced not only our planet but others as well.”
The Endurance mission was a NASA-funded project conducted through the Sounding Rocket Program at NASA’s Wallops Flight Facility in Virginia. The Svalbard Rocket Range is operated by Andøya Space. The European Incoherent Scatter Scientific Association (EISCAT) Svalbard radar, located in Longyearbyen, provided ground-based measurements of the ionosphere, which were essential for interpreting the rocket data. The United Kingdom Natural Environment Research Council (NERC) and the Research Council of Norway (RCN) funded the EISCAT radar for the Endurance mission. EISCAT is managed by research institutions and councils from Norway, Sweden, Finland, Japan, China, and the United Kingdom (the EISCAT Associates). The Endurance mission team includes affiliates from the Catholic University of America, Embry-Riddle Aeronautical University, the University of California, Berkeley, the University of Colorado at Boulder, the University of Leicester, the University of New Hampshire, and Penn State University.
