Interface Region Imaging Spectrograph

Interface Region Imaging Spectrograph (IRIS ) is a space telescope to explore the solar atmosphere. IRIS is a satellite in the NASA Explorer program. After reaching orbit IRIS has received the additional designation Explorer 94.


IRIS was selected on 19 June 2009 together with the later painted Gravity and Extreme Magnetism SMEX for the SMEX ( Small Explorer ) program of six candidates. Responsible for IRIS was the Lockheed Martin Solar and Astrophysics Laboratory ( LMSAL ). The satellite was built by Lockheed Martin Solar and Astrophysics Laboratory ( LMSAL ) and operated by this together with the Ames Research Center of NASA.

The mission of IRIS is to explore the outer regions of the solar atmosphere. IRIS is the energy and flow of plasma through the chromosphere and the transition region (English interface region) investigate in the solar corona in the ultraviolet region by means of imaging and spectrometry. This information on the energy transport into the corona and the solar wind are obtained, that contribute to understanding this hitherto not closely investigated dynamic region of the sun and other stars.

The telescope can detect only about one percent of the sun's surface per recording, but achieves a spatial resolution of 240 km. This IRIS complements the images of the research satellite Solar Dynamics Observatory (SDO ), provides the complete images of the sun in a lower resolution, for example, to study active regions.

The ultraviolet telescope allows the observation of solar matter in the temperature range from 5000 K to 65,000 K and solar flares up to 10 million K. This range was chosen in order to capture material in the photosphere, the transition layer and the chromosphere. The instrument comes on every five to ten seconds a picture and all of a second or two spectra.


IRIS satellite consists of a disc-shaped satellite structure containing the systems for supplying power, communication, control and position control, and transmits the UV telescope. Power is supplied by two folding solar boom. These are aligned with the entire satellite by three-axis stabilization to the sun. The data is transmitted to the ground station via an X-band radio link with a data transmission rate of up to 10 Mbits / second. With a mass of 200 kg, the satellite has a height of 2.1 m and with solar panels deployed booms a span of 3.7 m.

The IRIS satellite has only a research tool: an imaging UV spectrometer with 20 cm aperture and a high frame rate. It provides an image per second with a spatial resolution of 0.3 arcsec and a spectral resolution in the sub- angstrom range. The telescope was provided by the Smithsonian Astrophysical Observatory, while the spectrometer and the ultraviolet imaging camera from LMSAL developed and built.

For precise alignment of the observatory a Leitteleskop is additionally mounted parallel to the main instrument.

Mission History

The satellite was delivered on 16 April 2013, Vandenberg Air Force Base in California and assembled on May 29 at the Pegasus XL rocket. As a carrier aircraft was an L -1011 TriStar by Orbital Sciences called Stargazer. The carrier aircraft overturned on June 28 ( according to local time still June 27 ) at 01:27 UTC from Vandenberg Air Force Base and flew to Point Arguello Western Air Drop Zone ( WADZ ) at 36 ° 0 ' N, 123 ° 0' W36 - 123. There, the Pegasus rocket at 02:27 UTC from 39,000 ft (approx. 11,900 m) height was dropped, the engines ignited five seconds later. The three-stage Pegasus needed about 13 minutes to put the satellite into the designated orbit and there successfully suspend him. On July 25, 2013, the first image of the probe has been published.

The Pegasus XL rocket is being prepared for IRIS

IRIS is mounted on the launch vehicle