NASA scientists have discovered a third global energy field around Earth. Known as the ambipolar electric field, this force drives charged particles into space above the poles.
Two major global energy fields are known to exist around Earth – the gravity field, generated by the planet’s mass, and the electromagnetic field, which is produced by churning metals in the core. A third has been hypothesized for decades, but a new NASA study has finally confirmed it with measurements.
From the 1960s onwards, spacecraft that have flown over Earth’s poles have detected far more particles than expected flowing out of the atmosphere into space. This “polar wind” was strangely made up of particles moving at supersonic speeds even though they remained cold, contrary to expectations. As such, scientists theorized this could occur due to a phenomenon they called the ambipolar electric field.
According to the hypothesis, this field should begin at altitudes of around 250 km (150 miles) above the poles. It’s at that height in the atmosphere that electrons are more readily kicked out of hydrogen and oxygen atoms, leaving behind a positively charged ion. These ions are much heavier than electrons, so if gravity was the only force acting on them, over time they should separate as the ions fall downwards and the electrons are launched into space.
But because the ions and electrons have opposite charges, they remain attracted to each other. This means each pulls on the other as they travel in opposite directions, which has the end result of extending the “scale height” of the atmosphere over the poles, essentially making it denser higher up than it would otherwise be.
As intriguing as the story is, this ambipolar electric field would be extremely weak and only detectable across a distance of hundreds of miles, so no instruments have yet been sensitive enough to pick it up. Testing the hypothesis once and for all was the goal of NASA’s Endurance mission, which has now finally yielded results.
The mission culminated in a launch on May 11, 2022, from the northernmost rocket range in the world, located on the archipelago of Svalbard, north of Norway. There, Endurance launched on a 19-minute mission to study this field before splashing down into the Greenland Sea.
The onboard instruments measured changes in electric potential from the altitude where the field should begin – 250 km (150 miles) – up to the maximum height it reached, 768 km (477 miles). And sure enough, they detected a change of 0.55 volts.
“A half a volt is almost nothing — it’s only about as strong as a watch battery,” said Glynn Collinson, principal investigator of the Endurance mission. “But that’s just the right amount to explain the polar wind.”
It doesn’t sound like much, but for hydrogen ions, the most common type in the polar wind, this electric field exerted a force more than 10 times stronger than gravity, which helps launch them into space at supersonic speeds. Oxygen ions also get a substantial boost. The experiment also measured a 271% increase in the scale height of the ionosphere.
Now that this electric field has finally been detected, scientists can start to investigate how it’s affected the evolution of the atmosphere over Earth’s history.
The research was published in the journal Nature. The team describes the work in the video below.
Source: NASA
