Rockets to detect the electric circuit that feeds the northern lights

Rockets to detect the electric circuit that feeds the northern lights

Auroral currents are one type of field-aligned current – an electric current flows along the Earth’s magnetic field lines. The auroral stream carried charged particles (electrons and ions) from space into our atmosphere and back into space. Credit: NASA

A NASA-funded rocket mission is heading into space to measure the global electric circuit that lies beneath the northern lights. On its second flight into space, the Aurora Current and Electrodynamics Structures II, or ACES II, instrument will be launched from Andøya Space in Andenes, Norway. The launch window opens on November 16, 2022 at 6 PM local time.

Above us, electrons from space are streaming into our sky. As Earth’s magnetic field lines smooth out, they collide with gases in our atmosphere, causing them to glow. From Earth, observers see sparkling streaks of rubies and emeralds: Northern lights and Australis, or the Northern and Southern Lights.

But the aurora is just one part of a much larger system. Like a light bulb plugged into an electrical outlet, they are powered by a larger electrical circuit that connects our planet to near-Earth space.

“It’s these high-energy incoming electrons that produce the auroral display that we’re familiar with, but there’s also a part of the system that’s not visible,” said Scott Pounds, a University of Iowa physicist and ACES II principal investigator. Expedition.

Just as charged particles stream inward, a stream of charged particles streams from our atmosphere into space. Together, this inward and outward flow completes a universal electric circuit known as the auroral current.

Animation of the aurora borealis – the “ring” around the Earth’s polar regions in which the aurora borealis form. Credit: NASA/Cellab

One of the biggest mysteries about the auroral stream is what happens at the “turning point,” where the inflow ends and the outflow begins. This shift in ionospherea layer of our atmosphere that begins about 40 miles wide and extends into space, where charged particles and neutral gases coexist and interact.

The ionosphere is like a bustling frontier town where travelers from different lands, unfamiliar with each other’s customs, meet and exchange their goods. The ones that come from above are electrically charged particles from space. They are accustomed to the wide open space paths, rarely colliding with each other. they electric charge It keeps them tethered to the Earth’s magnetic field lines, which it orbits as it descends into our atmosphere or out into space.

Those that arrive from lower altitudes are neutral gases from our air. They crash into dense crowds, moving back and forth hundreds of times per second. Without an electric charge, they move freely across magnetic field lines It is carried by the wind.

In the ionosphere, these two groups merge — collide, merge with each other and separate again, interacting in complex ways. It is a chaotic scene. However, it is this turbulent mixing in the ionosphere that keeps the auroral stream churning.

Until now, most studies of the auroral stream have measured the inflows and outflows from the top of the ionosphere, making simplistic assumptions about what’s going on below. ACES II is designed to address this, by capturing a “snapshot” of the entire auroral stream at a single moment in time. The strategy is to launch two rockets: a “high fly” that measures particles flowing in and out of our atmosphere, and a “low fly” that will witness, at the same time, the dynamic exchange in the ionosphere that keeps it all flowing.

Rockets to detect the electric circuit that feeds the northern lights

ACES II Fact Sheet (click to enlarge) Credit: NASA

At the Andoya Space Center in Andenes, Norway, the auroral ellipse — the magnetic “ring” that surrounds Earth’s north magnetic pole and within which the aurora borealis form — passes overhead each night. Pounds and his team will wait until the auroral oval is above their heads — their evidence that the auroral stream is flowing overhead.

The team will then launch the aircraft high-flying, aiming for an altitude of about 255 miles (410 kilometers). Its goal is to see streams of particles flow in and out of our atmosphere. About two minutes later, they’ll shoot the low jet through the lower parts of the ionosphere, peaking at about 99 miles (159 km). Its goal is to capture the energy exchange that takes place at the tipping point, where the inward flow transforms into an outward flow.

The trajectory of the two missiles is aligned outer space and time, to ensure that they measure different parts of the same current. Like all sounding rockets, both high and low flying will take their measurements and return to Earth after a few minutes.

The ACES device has flown once before, launching from the Poker Flat Research Range in Fairbanks, Alaska, in 2009. There, it flew through an active and turbulent aurora. It was like measuring the weather during a particularly windy day.

“We got great results, but what we want to understand for this trip is ‘average condition,’” Pounds said. Andøya is located near Earth’s magnetic north pole, which means that the mildest and most common aurorae that aren’t as widespread as far south can more access to it.

If all goes as planned, ACES II will help scientists model the auroral stream as a whole, including its toughest part: our ionosphere.

“This is just one case – it doesn’t answer all the questions,” Pounds said. “But it does give us a data point that we need.”

the quote: Rockets to Uncover the Electric Circuit That Powers the Northern Lights (2022, November 16) Retrieved November 17, 2022 from

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