Rocket Launches Into an Aurora to Study Auroral Swirls

If you’ve ever wondered what makes the aurora take on the amazing forms it does you’ve got company. Marilia Samara and the crew of aurora researchers at Alaska’s Poker Flat Range head up the NASA-funded Ground-to-Rocket Electrodynamics-Electrons Correlative Experiment, or GREECE. Their mission is to understand what causes the swirls seen in very active auroras. 

Robert Michell, who built some of the instruments on the sounding rocket, and Marilia Samara, the principal investigator for the GREECE project. Credit: NASA
Robert Michell, who built some of the instruments on the sounding rocket, and Marilia Samara, the principal investigator for the GREECE project. Credit: NASA

“Our overarching goal is to study the transfer of energy from the sun to Earth,” said Samara, a space scientist at the Southwest Research Institute, or SwRI, in San Antonio, Texas. “We target a particular manifestation of that connection – the aurora.”

Here’s what we know. Electrons and protons from the sun come charging into Earth’s magnetic domain called the magnetosphere and strike and energize molecules of oxygen and nitrogen in the atmosphere between 60 and 200 miles overhead. The molecules release that extra energy as the greens, reds and purples of the northern lights.

Earth has a magnetic field much like an ordinary refrigerator magnet but shaped by charged particles – electrons and protons – flowing from the sun called the solar wind. When those particles travel down the field lines and excite atmospheric gases, they create the familiar parallel rays seen in auroras. Credit: Greg Shirah and Tom Bridgman, NASA/Goddard Space Flight Center Scientific Visualization Studio (left); Bob King (right)
Earth has a magnetic field much like an ordinary refrigerator magnet but shaped by charged particles flowing from the sun called the solar wind. When those particles travel down the planet’s magnetic field lines and excite atmospheric gases, they create the familiar parallel rays seen in auroras. Credit: Greg Shirah and Tom Bridgman, NASA/Goddard Space Flight Center Scientific Visualization Studio (left); Bob King (right)

And those picket-fence, parallel rays that can suddenly spring from a quiet arc are created by billions of electrons spiraling down individual magnetic field lines, crashing into atoms and molecules as they go. Because the lines of magnetic force are closely bunched, as shown in the illustration above, we see side-by-side, tightly spaced rays.

What we less about is how the twists, swirls and eddies form.

Wave clouds forming over Mount Duval, Australia from a Kelvin-Helmholtz Instability. Credit: GRAHAMUK / English language Wikipedia
Wave clouds forming over Mount Duval, Australia from a Kelvin-Helmholtz Instability. Credit: GRAHAMUK / English language Wikipedia

Scientists suspect the swirls may take shape as a result of Kelvin-Helmholtz instabilities or Alfven waves. The first occurs when two fluids or gases moving at different rates of speed flow by one another. In a familiar example, wind blowing over water creates ripples that are amplified into curling, white-topped waves.

Alfven waves are created when flows of electrified particles from the sun (plasma) interact with Earth’s magnetic field. To study the structures, sounding or research rockets are launched directly into an active display of northern lights to gather electrical and magnetic measurements. At the same time, cameras on the ground record the dance of rays and arcs above. Samilla and her team at GREECE then compare the aurora’s shifting shapes with real-time data gathered during the rocket’s 600 seconds of flight.

Still and video cameras on the ground simultaneously image the aurora as the instrument-laded rocket flies directly into the aurora to gather data. Credit: Marilia Samara / Robert Michell / SwRI
Still and video cameras on the ground simultaneously image the aurora as the instrument-laded rocket flies into the aurora to gather data. Credit: Marilia Samara / Robert Michell / SwRI

“Auroral curls are visible from the ground with high-resolution imaging,” said Samara. “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.”


Poker Flat rocket launch – Jason Ahrns

And that’s exactly what the team did this past Monday morning March 3. Conditions looked good from Poker Flat the previous evening with a flurry of red and green arcs after sunset. At about 2:10 a.m. Alaska time, after careful monitoring of activity,  the order was given to launch.

“It was a wonderful auroral event,” said Kathe Rich, Poker Flat Range manager. “We got good data throughout the flight, and all the instruments worked.”

Time exposure showing the trail of the rocket after it was launched into the aurora over Poker Flat early Monday morning March 3, 2014. Credit: Jason Ahrns
Time exposure showing the trail of the rocket after it was launched into the aurora over Poker Flat early Monday morning March 3, 2014. Credit: Jason Ahrns

The rocket soared to an altitude of 220 miles (354 km) and recorded data as the video and still cameras whirred on the ground during the 10 minute 15 second long flight.

There must be a bunch of happy scientists at the Range this week. They have their work cut out for them; those few minutes of data collecting will mean years of work to track down the cause of the beautiful curlicues that make our hearts leap at the sight.

Happy researchers at the Poker Flat Research Range. Credit: Lex Wingfield / NASA
Happy researchers at the Poker Flat Research Range. Credit: Lex Wingfield / NASA

Poker Flat Research Range, the world’s only scientific rocket launching facility owned by a university, is located about 30 miles north of Fairbanks, Alaska and is operated by the University of Alaska’s Geophysical Institute under contract with NASA. Most of the research there involves the aurora with sounding rocket launches done about once a year. While waiting for the right moment to launch, members of the team exercise their poetic side by writing and sharing haikus about their beloved aurora. Here’s a sampling, and there are more HERE.

Dim, wide green madness
Electromagnetic ghost
Surrender your soul
– EM

Hey elusive arc
Zenith is over there, dude
It’s about damn time
-EM

Oh Oh Oh Oh Oh
Oh Oh Oh Oh Oh Oh Oh
So ready to launch!
-JC

While the cause of auroras is understood, what causes the swirl shapes is an open question. University of Alaska researchers at Poker Flat hope to find an answer. Aurora photographed on Dec. 15, 2012 from Tromso, Norway. Credit: Ole Salomonsen
While the cause of auroras is understood, what causes the swirl shapes is an open question. University of Alaska researchers at Poker Flat hope to find an answer. Aurora photographed on Dec. 15, 2012 from Tromso, Norway. Credit: Ole Salomonsen

Dramatic Rocket Launch Into an Aurora

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Over the weekend, a two-stage sounding rocket launched into a sky shimmering with green aurora. On board were instruments that will help shed new light on the physical processes that create the Northern Lights and further our understanding of the complex Sun-Earth connection.

“We’re investigating what’s called space weather,” said Steven Powell from Cornell University. “Space weather is caused by the charged particles that come from the Sun and interact with the Earth’s magnetic field. We don’t directly feel those effects as humans, but our electronic systems do.”

The rocket launched on Feb. 18, 2012 from the Poker Flat Research Range in Fairbanks, Alaska. The rocket sent a stream of real-time data back before landing some 200 miles downrange shortly after the launch.

Instruments sampled electric and magnetic fields that are generated by the aurora. While the Sun heads toward solar maximum, emissions from the Sun are more likely to head Earth’s way and cause more interference with GPS transmissions, satellite internet and other signals.

“We are becoming more dependent on these signals,” Powell said. “This will help us better understand how satellite signals get degraded by space weather and how we can mitigate those effects in new and improved GPS receivers.”

Other instruments studied charged particles in Earth’s ionosphere that get sloshed back and forth by a specific form of electromagnetic energy known as Alfvén waves. These waves are thought to be a key driver of “discrete” aurora – the typical, well-defined band of shimmering lights about six miles thick and stretching east to west from horizon to horizon.

These waves are akin to a guitar string when “plucked” by energy delivered by the solar wind to Earth’s magnetosphere high above.

“The ionosphere, some 62 miles up, is one end of the guitar string and there’s another structure over a thousand miles up in space that is the other end of the string,” said Marc Lessard, who worked with graduate students from the University of New Hampshire’s Space Science Center to monitor the launch. “When it gets plucked by incoming energy we can get a fundamental frequency and other ‘harmonics’ along the background magnetic field sitting above the ionosphere.”

The rocket was a 46-foot Terrier-Black Brant model that was sent right through the aurora 350 km (217 miles) above Earth.

This is not the first sounding rocket flight from Poker Flats to launch into an aurora. In 2009 two rockets flew through aurorae to help refine current models of aurora structure, and provide insight on the high-frequency waves and turbulence generated by aurorae.

Sources: University of New Hampshire, Cornell University