NASA’s twin Radiation Belt Storm Probes (RBSP) launched Aug. 30 from Florida’s Cape Canaveral Air Force Station atop a United Launch Alliance Atlas 5 rocket.

Liftoff had been planned for Aug. 23, but was pushed back a week by a combination of technical glitches and foul weather.

After a 60-day commissioning period on orbit, the Johns Hopkins University Applied Physics Laboratory-built spacecraft will begin the science phase of their two-year mission, which aims to help scientists understand how Earth’s two doughnut-shaped Van Allen radiation belts affect our planet’s space weather.

Such information could have considerable practical applications, researchers said, since extreme space weather can knock out satellites and disrupt GPS signals, radio communications and power grids.

“RBSP will be able to predict the extremes and the dynamic conditions of space weather,” Mona Kessel, program scientist for the $686 million mission, told reporters before the launch.