When the sun emits high-energy particles, the earth’s magnetic field catches most of them in the Van Allen Radiation Belts.

To try and understand them better, a NASA mission last week launched two unmanned aircraft into the Belts. The University of Minnesota is leading the Electric Field and Waves Suite, one of five experiments onboard each aircraft.

The Belts are two donut-shaped regions surrounding earth that contain radiation levels unsafe for humans and most aircraft systems. The mission could, for example, help researchers design aircraft to better prevent radiation exposure.

“This is one of the few NASA missions in our field where the applied science is playing a reasonably large role,” said John Wygant, University physics professor and EFW principal investigator.

“Usually, it’s just basic research. Here, it combines both.”

When the sun emits shockwaves and coronal mass ejections, plasma can cause the donut shape of the Belts to compress, increasing the particle acceleration in the earth’s magnetic field.

Wygant said the EFW will study the differences in electric fields during these times.

The aircraft side

To study the 3-D electric fields, the aircraft have three pairs of cable probes, each extending more than 160 feet from the aircraft.

The aircraft are only about 6 feet wide and 4 feet tall, but they weigh just under 1,500 pounds.

Each has about 4 square yards of solar panels that power the entire aircraft. When they’re not facing the sun, the aircraft run on battery power.

Researchers need two aircraft to form a 3-D picture of the kinds of radiation and particles in the Belts. Having two aircraft also helps verify observations — if something happens to one aircraft but not the other, it could just be a fluke.

The twin aircraft will therefore follow identical elliptical orbits through the Belts for two years to measure various solar events.

The human side

Wygant said researchers have tested the aircraft exhaustively for the past week. On Wednesday they turned on the instruments. He said he’ll have to wait another week before the experiment he’s directing deploys.

But to Wygant, a week isn’t too long to wait — he’s been waiting for a mission like this since 1998. He was on the team that pitched the project to NASA nine years ago and became the principal investigator when NASA chose the University to lead the EFW six years ago.

Graduate student Kris Kersten joined the mission just six months ago, and said he has enjoyed seeing the work that goes into the planning stages of a mission of this magnitude.

“It’s interesting to see how everybody’s work all comes together,” Kersten said.

Wygant said he was most excited to discover new, unexpected things about the Belts.

“In science, every time you do something new, you find something unexpected — stuff that you didn’t even plan for,” he said. “That’s the way it works.”