L-1011 takes off from Vandenberg carrying Pegasus XL rocket

An Orbital Sciences L-1011 carrier aircraft takes off from Vandenberg Air Force Base, Calif., on a mission to launch NASA's IRIS spacecraft into low-Earth orbit. IRIS, short for Interface Region Imaging Spectrograph, was launched on Thursday aboard an Orbital Sciences Pegasus XL rocket released from the L-1011.

IRIS is a NASA Small Explorer Mission to observe how solar material moves, gathers energy and heats up as it travels through a little-understood region in the sun's lower atmosphere. This interface region between the sun's photosphere and corona powers its dynamic million-degree atmosphere and drives the solar wind.