Launching into the Aurora Borealis

A psychedelic array, the aurora borealis are shimmering lights resulting from electrons form the sun colliding with particles in the Earth’s atmosphere. Against an ocean of stars, the phenomenon almost appears as cloudy drops of paint dispersing through water.

NASA, this winter, will launch two sounding rockets through the Northern Lights in Norway to study what is known as a cusp aurora, when “energetic particles are accelerated downward into the atmosphere directly from the solar wind—that is, the constant outward flow of solar material from the sun,” according to NASA. Cusp auroras, though not rare, pose a problem for visibility, as they often occur during daylight hours.

However, “the magnetic pole is tilted towards North America, putting this magnetic opening—the cusp—at a higher latitude on the European side,” said Jim LaBelle, principal investigator of the CAPER (Cusp Alfven and Plasma Electrodynamics Rocket) sounding rocket, one of the two rockets slated for launch. “Combine that extra-high latitude with the winter solstice—when nights are longest, especially as you go farther north—and you can sometimes see this daytime aurora with the naked eye.”

Each rocket will collect data for only a handful of minutes.

CAPER

CAPER is the first rocket NASA will launch this winter. It will investigate the electromagnetic waves responsible for accelerating electrons downwards towards the Earth’s atmosphere or up into space.

CAPER will carry three instruments on its journey. The first will measure low-frequency electromagnetic waves, the second will measure high-frequency electromagnetic waves and the third will measure the amount of particles at different energy levels.

“The difficulty is measuring the high-frequency waves and their associated particles,” said LaBelle. “They’re moving at up to a million cycles per second, so the instruments have to be able to detect changes in the waves and collect enough particles to match up.”

RENU 2

The second rocket, the Rocket Experiment for Neutral Upwelling, or RENU 2, “will study the relationship between the inflow of electrons that creates the cusp aurora, electric currents flowing along magnetic field lines and dense columns of heated neutral atoms in the upper atmosphere,” according to NASA.

Some satellites, while orbiting through Earth’s magnetic cusp, have encountered “speed bumps” causing acceleration to briefly slow. This indicates small vertical slices of higher-density neutral atoms, which are more difficult to travel through.

“When solar wind electrons collide with atmospheric electrons, they transfer some of their energy, heating the atmospheric electrons,” said Marc Lessard, RENU 2’s principal investigator. “The higher heat means the electron populations expand upward along the magnetic field lines.”

The amalgam of negatively-charged, positive-charged and neutral particles increases the atmospheric density in columns. NASA will use instruments to measure magnetic fields, neutral and charged particle flows and temperatures on the sounding rocket.