The Big Mystery of Little Particles

In May 2022, a rocket launched from the icy, northernmost reaches of the archipelago of Svalbard in Norway. It was on a mission to solve a nearly 60-year-old mystery.

Named Endurance, after the ship that brought explorer Ernest Shackleton to Antarctica, the NASA rocket soared to 477 miles above Earth’s surface, collecting data that scientists hoped would reveal the source of an elusive atmospheric force.

Two years later, NASA researchers confirmed a groundbreaking discovery: The first direct measurements of Earth’s ambipolar electric field.

In their study, published in the journal Nature, the team explained that this weak electric field – about 0.55 volts, which is enough to power a watch – plays an essential role in driving a phenomenon called the “polar wind.”

“A half a volt is almost nothing,” Glyn Collinson, the Endurance mission’s principal investigator at NASA’s Goddard Space Flight Center, said in a statement. “But that’s just the right amount to explain the polar wind.”

Scientists first noticed this electrical field back in the 1960s, when a US spacecraft detected particles streaming out of Earth’s atmosphere near the poles, according to Popular Mechanics.

This “polar wind” baffled scientists at the time, as the particles were cold, showing no signs of being heated by solar radiation. But because astronomers were shooting for the Moon at the time, they left the mystery for future generations to solve.

Now, data from Endurance showed that this ambipolar field tethers the particles together and pushes them into space. This field is generated around 150 miles above Earth’s surface where atoms split into electrons and ions – known as the ionosphere.

Despite having a weak electrical field, it lifts charged particles to escape Earth’s atmosphere at supersonic speeds, extending the ionosphere’s height by 271 percent. In turn, it acts as a protective shield that blocks harmful solar radiation from reaching us.

Collinson likened the field to “a conveyor belt, lifting the atmosphere up into space.”

He added that this elusive field has been subtly shaping Earth’s atmosphere since the planet’s formation. He hopes that further studies on the phenomenon can assess its impact on our planet’s evolution and its potential role in sustaining atmospheres across the cosmos.

The ambipolar field is believed to exist on other planets, including Mars and Venus, wrote the British Antarctic Society.

“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.”