It seems this month is aurora exploration season for NASA’s fleet of sounding rockets because this coming Friday, April 1, another pair of suborbital rockets will launch to investigate something connected to aurorae.

As the charged electrons which cause aurorae streak from the Sun to Earth, they first encounter the magnetosphere and then something called the boundary layer hundreds of kilometers above the Earth’s surface. The boundary layer is where the very limits of the atmosphere interact with the Earth’s magnetosphere. This boundary layer is composed of two parts – the ionosphere and thermosphere – and the transfer of energy from the solar wind is complicated by the ionosphere being electrically charged while the thermosphere is not charged, or neutral.

The experiment called Ion-Neutral Coupling during Active Aurora (INCAA) will investigate what happens when the solar wind hits this boundary layer. It will figure out exactly what height the energy is transferred into the ionosphere and the thermosphere, the highest layer of the proper atmosphere. Aurorae can change the ionosphere locally and therefore where the energy goes, which is why this experiment needs to happen during an aurora. One known place for the energy to go is the less rarified (thicker) part of the atmosphere, interfering with orbiting satellites.

A recent example of this was the Starlink 4-7 mission in early February of this year, where a solar storm inflated the atmosphere and ultimately caused 38 of the 49 satellites to stay in safe mode and not raise their orbits, causing them to reenter the atmosphere only a few after launch.

The INCAA experiment will see two rockets launched in short succession from the Poker Flats Research Range in Alaska. The first rocket will deploy small amounts of barium to get ionized by the aurora at several altitudes up to 128 kilometers, and a second, smaller rocket will carry instruments to take data. Ground-based instruments will also be used to observe the clouds.

More Information

NASA Goddard press release

University of Alaska Fairbanks press release