A caper inside an aurora borealis


Scientists study the waves that accelerate electrons into our atmosphere.


The daytime aurora borealis, observed from an all-sky camera in Longyearbyen, Norway.
KJELL HENRIKSEN OBSERVATORY/UNIS/F. SIGERNES

Now this would be the ultimate Northern Lights tour - flying right through an active aurora borealis.

Earlier this month, the CAPER-2 mission launched from the Andøya Space Centre in Andenes, Norway, with the aim of studying the waves that accelerate electrons into our atmosphere.

It wasn’t up there for long. CAPER-2 (short for Cusp Alfvén and Plasma Electrodynamics Rocket-2) utilised a sounding rocket, which is designed to carry scientific instruments on short, targeted trips to space before falling back to Earth.

They are ideal for launching into transient events, such as the sudden formation of the aurora borealis, providing – in this case – a glimpse of how particles get accelerated throughout space.

"Throughout the universe you have charged particles getting accelerated: in the Sun's atmosphere, in the solar wind, in the atmospheres of other planets and in astrophysical objects," says Jim LaBelle, space physicist and US-based principal investigator for the CAPER-2 mission.

"An aurora presents us with a local laboratory where we can observe these acceleration processes close at hand."

The CAPER-2 team is interested in what happens just before an aurora starts glowing.

Electrons, pouring into our atmosphere from space, collide with atmospheric gases and trigger the aurora's glow. Somehow, they pick up speed along the way.

"By the time they crash into our atmosphere, these electrons are traveling over 10 times faster than they were before," says Doug Rowland, space physicist at NASA's Goddard Space Flight Centre.

"We still don't understand the fundamental physics of how that happens."

The mission examined an aurora that forms during the day and, unlike night-time auroras, is triggered by electrons that stream in directly from the Sun.

We know far less about them, and the research team is focusing on how the electrons that create daytime auroras are jostled around by waves, in ways that may or may not differ from night-time auroras.

Meeting the aurora right where they form is the best way to understand physical processes that are far too large to replicate in a lab.

And Northern Norway is one of the few places that can put a rocket within range of the daytime aurora. Every day, it rotates under an opening in Earth's magnetic field known as the northern polar cusp, where particles from the Sun can funnel into our upper atmosphere.

The CAPER-2 mission was part of the Grand Challenge Initiative, an international campaign to explore the Auroral Cusp.

  1. https://www.andoyaspace.no/the-grand-challenge-initiative/
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