The sun has spewed a pair of solar particle blasts toward three NASA unmanned spacecraft in recent days -- including one on a University of Maryland-led mission.
But the risk of electronic malfunctioning is expected to be low and no impact on Earth is forecast, NASA said.
The coronal mass ejections occurred at 8:36 p.m. Tuesday and 6:54 a.m. Wednesday. The CMEs sent solar particles flying at about 400 miles per second, a rate that would have them reach Earth within a few days.
But at that speed, the particles are not expected to generate any noticeable impacts on Earth. A typical concern would be a geomagnetic storm that can disrupt satellite signals and GPS.
The CME could, however make for a brilliant aurora borealis, or "Northern Lights".
One of the spacecraft in the path of one of the CMEs is known as EPOXI, a mission the University of Maryland, College Park, is leading to explore faraway planets, comets and asteroids. The mission " combines two exciting science investigations in an entirely new mission that re-uses the Deep Impact spacecraft already in orbit around the Sun."
Deep Impact launched in 2004 and a year and a half later landed on the surface of comet Tempel 1.