A NASA-funded sounding rocket arcs into auroras over Venetie, Alaska, on March 3. (Photo: NASA/Christopher Perry)
The northern lights have been dazzling people around the world lately, thanks to the ongoing solar maximum. But while most of us are content to see an aurora, even if only on our computer screens, a group of scientists celebrated the northern lights in Alaska this week by shooting them with a rocket.
Launched from the Poker Flat Research Range on March 3, the sounding rocket spent just 10 minutes aloft as it pierced a 6 a.m. aurora burst over the village of Venetie. But that's all the time it needed to gather data on particles and electric fields in the auroras, part of a NASA-funded effort to figure out what causes their swirling shapes. If scientists can untangle these "auroral curls," they hope to shed new light on the sun-Earth relationship, especially on how solar wind affects Earth's magnetosphere.
"Our overarching goal is to study the transfer of energy from the sun to Earth," says Marilia Samara, lead scientist for the Ground-to-Rocket Electrodynamics-Electrons Correlative Experiment, or GREECE, in a statement. "We target a particular manifestation of that connection: the aurora."
Green auroras, like this one over Venetie, are caused by solar particles hitting oxygen in the atmosphere. (Photo: NASA/Christopher Perry)
These eerie lights appear in high-latitude skies when a blast of solar wind reaches Earth's upper atmosphere, generating electric currents and triggering a shower of particles some 60 to 200 miles above the surface. As these particles strike oxygen and nitrogen in the atmosphere, they release a flash of colored light. Scientists have a good grasp on how all this works, but they're looking for more small-scale details about aurora formation and the physics of plasma in general.
"Auroral curls are visible from the ground with high-resolution imaging," Samara says. "And we can infer from those observations what's happening farther out. But to truly understand the physics we need to take measurements in the aurora itself."
The sounding rocket blasts off from Poker Flat Research Range at 6:09 a.m. EST on March 3. (Photo: NASA/Christopher Perry)
Using information from the rocket as well as ground-based imagers, Samara's team plans to test various explanations for the origin of auroral curls. Suspects include the "Kelvin-Helmholtz instability," a combination of high- and low-speed flows that's also seen in the ocean, and Alfven waves, a type of electromagnetic wave that occurs only in plasmas.
"The conditions were optimal," Samara said after the launch. "We can't wait to dig into the data."
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