IRIS - The Interface Region Imaging Spectrograph - is a NASA Small Explorer Mission to examine how solar material moves, gathers energy, and heats up as it travels through a little-understood region in the sun's lower atmosphere, the chromosphere, to the corona.
Observing how material and energy move through this region will provide more insight into the dynamics of the Sun to help explain what causes the ejection of solar material, in the form of the steady solar wind or larger, explosive Coronal Mass Ejections - that influence near-Earth space weather.
As a Small Explorer Mission, IRIS has an overall budget of $120 Million. Lockheed Martin Solar and Astrophysics Laboratory in Lockheed's Advanced Technology Center is the principle investigator institution and overall responsibility for the mission while Lockheed Martin Civil Space, NASA Ames, Smithsonian Astrophysical Laboratory, Montana State University, Stanford University and the University of Oslo are contributors.
IRIS launches on a Pegasus XL rocket in June 2013 (possibly the final Pegasus to fly) and has a primary mission of two years to collect UV spectra and images of the sun with unprecedented spatial and temporal resolution showing even small solar features of just 250 Kilometers in short exposures that enables IRIS to track dynamic events. A two-year extension to the mission is already proposed and more extensions are possible as well - pending good spacecraft performance.