The two Radiation Belt Storm Probes (RBSP) spacecraft slated to launch in August aboard a United Launch Alliance Atlas 5 rocket arrived May 1 at NASA’s Kennedy Space Center in Florida to begin a two-year mission to study the extremes of space weather.

The twin RBSP left the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Md., in custom-made shipping containers April 30 and were flown from Andrews Air Force Base to Kennedy in a U.S. Air Force C-17 cargo plane. Over the next several weeks, APL engineers and scientists will prepare RBSP for launch.

APL built the probes under a $500 million cost-plus contract awarded in 2006. Late deliveries of several instruments due to design and parts related issues prompted NASA last summer to delay the mission’s launch readiness date from May 2012 to September 2012. Launch is slated for Aug. 23.