On the sun, magnetic reconnection unleashes solar flares, each as powerful as 1 million atomic bombs. Such solar activity can trigger magnetic storms and aurora displays on Earth.

NASA is spending about $1.1 billion on the project, known as Magnetospheric Multiscale, or MMS, in an effort to understand how the energy is generated and released. The satellites will fly directly into reconnection zones 44,000 to 95,000 miles (70,811 to 152,888 km) above Earth and map what happens when magnetic field lines realign.

"The MMS mission will conduct a definitive experiment in space that will finally allow us to understand how magnetic reconnection works," lead researcher Jim Burch from the Southwest Research Institute in San Antonio, Texas, told reporters at a pre-launch press conference.

The research may have some practical spinoffs as well. Efforts to harness nuclear fusion in laboratories have been stymied by magnetic reconnection, which causes temperatures to drop in the fusion chambers.

It also may help forecasters predict dangerous solar storms, which can knock out power grids on Earth and disrupt radio, GPS and satellite signals.

The mission is designed to last two years.