The Interface Region Imaging Spectrograph (IRIS) is a NASA Small Explorer class solar mission. It was launched from a Pegasus XL flying out of Vandenberg AFB in California. The rocket was deployed from an Orbital L-1101 carrier aircraft flying over the Pacific Ocean at an altitude of 39,000 feet (about 12 km), roughly 100 miles northwest of Vandenberg. The rocket was dropped at 7:27 p.m. PDT on 27 June 2013 (02:27 UT, 28 June).

IRIS is intended to advance Sun-Earth connection studies by tracing the flow of energy and plasma into the corona and heliosphere for which no suitable observations exist. To achieve this IRIS will obtain high-resolution UV spectra and images of the sun's chromosphere, specifically on the non-thermal energy that creates the corona and the solar wind.

IRIS seeks to determine: (1) the types of non-thermal energy which dominate in the chromosphere and beyond; (2) the means by which the chromosphere regulates mass and energy supply to the corona and heliosphere; and, (3) how magnetic flux and matter rise through the lower solar atmosphere, and the role played by flux emergence in flares and mass ejections. To answer these questions, IRIS will utilize a single intrument, a multi-channel imaging spectrograph. See the experiment description for details on the IRIS instrument.