Explorer-1 [Prime], also known as E1P and Electra, was a CubeSat-class picosatellite built by the Space Science and Engineering Laboratory (SSEL) at Montana State University. It was launched aboard a Taurus-XL rocket from Vandenberg Air Force Base, California on 4 March 2011, but failed to achieve orbit after the rocket malfunctioned. As part of NASA's ELaNA program, E1P was to be launched along with NASA's Glory satellite, Kentucky Space's KySat-1 and the University of Colorado-Boulder's Hermes CubeSats. There was a spare, Explorer-1 Prime Unit 2, that was launched with NPP.