Long-Sought Global Electric Field on Earth Reported by NASA, With Embry-Riddle Collaborators
An Embry-Riddle Aeronautical University team led by Dr. Aroh Barjatya, professor of Engineering Physics and director of the Space and Atmospheric Instrumentation Lab (SAIL), helped researchers with NASA’s Goddard Space Flight Center (GSFC) achieve an important scientific first — the successful measurement of a planet-wide electric field, known as the “ambipolar electric field.”
The research, published on Aug. 28, 2024, in the journal Nature, was led by Dr. Glyn Collinson of NASA GSFC. Co-authors included Barjatya and five others from Embry-Riddle — research scientists Dr. Robert Clayton and Dr. Shantanab Debchoudhury, and doctoral students Rachel Conway, Nathan Graves and Henry Valentine.
In the summer of 2022, the Embry-Riddle team had participated in NASA sounding rocket launches — one in far-north Ny Ålesund, Norway, and another at NASA’s Wallops Flight Facility in Virginia. The rocket that launched from Wallops, known as the Sporadic-E ElectroDynamics Demonstration Mission, or SpEED Demon, was testing new instruments slated to fly on NASA rocket missions.
Instruments aboard SpEED Demon — as well as one aboard the Endurance rocket, which was launched from Norway in May 2022 — were designed by Graves and Valentine, both Engineering Physics students. They began working on the instruments as undergraduates and are now pursuing their Ph.D. degrees in the program, Barjatya said. Both traveled to Ny Alesund for Endurance launch activities.
Rachel Conway, another Engineering Physics Ph.D. student guided by Barjatya, analyzed the Embry-Riddle instrument flight data.
“My time working on Endurance data has challenged my understanding and reinforced my curiosity of our planet and its complexities,” Conway said. “Not only has this work been meaningful, but it ultimately led to a major milestone in my academic career at Embry-Riddle. It has been an absolute privilege to be a part of this team and to play a role in this discovery. I can't wait to see what the future holds!”
Embry-Riddle collaborators on a major NASA discovery included (L-R): Henry Valentine, Dr. Robert Clayton, Nathan Graves and Dr. Aroh Barjatya, shown here in Ny Ålesund, Norway, where they participated in NASA sounding rocket launches. Valentine and Graves are now doctoral students at Embry-Riddle. Not shown are two other Embry-Riddle team members, doctoral student Rachel Conway and research scientist Dr. Shantanab Debchoudhury. (Photo: Embry-Riddle)
Understanding the NASA Discovery
Above the Earth’s poles, the ambipolar electric field sends a steady stream of charged particles into space, NASA explained. A key driver of the 'polar wind,' the ambipolar electric field may be “as fundamental as Earth’s gravity and magnetic fields,” NASA said, adding that “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 still to be explored.”
An announcement from NASA explained further:
Some amount of outflow from our atmosphere was expected. Intense, unfiltered sunlight should cause some particles from our air to escape into space, like steam evaporating from a pot of water. But the observed polar wind was more mysterious. Many particles within it were cold, with no signs they had been heated — yet they were traveling at supersonic speeds.
“Something had to be drawing these particles out of the atmosphere,” said Glyn Collinson, principal investigator of Endurance at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the [Nature] paper. Scientists suspected a yet-to-be-discovered electric field could be at work.
The hypothesized electric field, generated at the subatomic scale, was expected to be incredibly weak, with its effects felt only over hundreds of miles. For decades, detecting it was beyond the limits of existing technology. In 2016, Collinson and his team got to work inventing a new instrument they thought was up to the task of measuring Earth’s ambipolar field.
NASA reported that on May 11, 2022, the Endurance rocket launched, reached an altitude of 477.23 miles and splashed down 19 minutes later in the Greenland Sea. Endurance then measured a charge in electric potential, across the 322-mile altitude range where it collected data, of only 0.55 volts. Provided by SAIL at Embry-Riddle, a Sweeping Langmuir Probe instrument was crucial for understanding the flight data and determining the ambipolar electric field.
To put this finding into context, NASA wrote:
“A half a volt is almost nothing — it’s only about as strong as a watch battery,” Collinson said. “But that’s just the right amount to explain the polar wind.”
Hydrogen ions, the most abundant type of particle in the polar wind, experience an outward force from this field 10.6 times stronger than gravity. “That’s more than enough to counter gravity — in fact, it’s enough to launch them upwards into space at supersonic speeds,” said Alex Glocer, Endurance project scientist at NASA Goddard and coauthor of the paper.
“It has been an absolute privilege to be a part of this team and to play a role in this discovery. I can't wait to see what the future holds!”
Heavier particles also get a boost. Oxygen ions at that same altitude, immersed in this half-a-volt field, weigh half as much. In general, the team found that the ambipolar field increases what’s known as the “scale height” of the ionosphere by 271%, meaning the ionosphere remains denser to greater heights than it would without it.
“It’s like this conveyor belt, lifting the atmosphere up into space,” Collinson added.
Endurance’s discovery has opened many new paths for exploration. The ambipolar field, as a fundamental energy field of our planet alongside gravity and magnetism, may have continuously shaped the evolution of our atmosphere in ways we can now begin to explore. Because it’s created by the internal dynamics of an atmosphere, similar electric fields are expected to exist on other planets, including Venus and Mars.
In addition to Embry-Riddle, other NASA Goddard Space Flight Center collaborators included the Catholic University of America, the University of California, Berkeley, the University of Colorado at Boulder, space physicist Susie Imber of the University of Leicester, U.K., the University of New Hampshire and Penn State University.
Endurance was a NASA-funded mission conducted through the Sounding Rocket Program at NASA’s Wallops Flight Facility in Virginia. The Svalbard Rocket Range is owned and operated by Andøya Space. The European Incoherent Scatter Scientific Association (EISCAT) Svalbard radar, located in Longyearbyen, made ground-based measurements of the ionosphere critical to interpreting the rocket data. The United Kingdom Natural Environment Research Council and the Research Council of Norway funded the EISCAT radar for the Endurance mission. EISCAT is owned and operated by research institutes and research councils of Norway, Sweden, Finland, Japan, China and the United Kingdom (the EISCAT Associates).
The Nature paper is titled “Earth’s ambipolar electrostatic field and its role in ion escape to space.” (DOI: 10.1038/s41586-024-07480-3.) Funding for Embry-Riddle’s contribution to the research was provided by NASA under the grant number 80NSSC19K1089.
*NASA and Embry-Riddle sources contributed to this report.