The Interface Region Imaging Spectrograph (IRIS) is a NASA solar observation satellite. The mission was funded through the Small Explorer program to investigate the physical conditions of the solar limb, particularly the chromosphere of the Sun. The spacecraft consists of a satellite bus and spectrometer built by the Lockheed Martin Solar and Astrophysics Laboratory (LMSAL), and a telescope provided by the Smithsonian Astrophysical Observatory. IRIS is operated by LMSAL and NASA's Ames Research Center.
The satellite's instrument is a high-frame-rate ultraviolet imaging spectrometer, providing one image per second at 0.3 arcsecond spatial resolution and sub-ångström spectral resolution.
NASA announced on 19 June 2009 that IRIS was selected from six small explorer mission candidates for further study, along with the Gravity and Extreme Magnetism (GEMS) space observatory.
The spacecraft arrived at Vandenberg Air Force Base, California, on 16 April 2013 and was successfully launched on 27 June 2013 by a Pegasus-XL rocket. IRIS achieved first light on 17 July 2013. NASA noted, "IRIS's first images showed a multitude of thin, fibril-like structures that have never been seen before, revealing enormous contrasts in density and temperature occur throughout this region even between neighboring loops that are only a few hundred miles apart." On 31 October 2013, calibrated IRIS data and images were released on the project website. A preprint describing the satellite and initial data has been released on the arXiv.
NASA's newest sun-watcher, the Interface Region Imaging Spectrograph, launched in 2013 with a specific goal: track how energy and heat coursed through a little understood region of the sun called the interface region. Sandwiched between the solar surface and its outer atmosphere, the corona, the interface region is where the cooler temperatures of the sun's surface transition to the hotter temperatures above. Moreover, all the energy to power the sun's output -- including eruptions such as solar flares and the sun's constant outflow of particles called the solar wind -- must make its way through this region. See:
NASA's IRIS Helps Explain Mysterious Heating of the Solar Atmosphere