New solar research satellite embarks on two-year mission

Scientists will soon be able to observe the sun like never before, thanks to the successful launch of the Interface Region Imaging Spectrograph (IRIS) spacecraft. IRIS was launched Thursday at 10:27 p.m. EDT aboard a Pegasus XL rocket on a mission to study the solar atmosphere.

"IRIS will help scientists understand the mysterious and energetic interface between the surface and corona of the sun,” said John Grunsfeld, NASA's associate administrator for science in Washington.

IRIS will 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. The interface region also is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate.

The Pegasus rocket, carrying IRIS, was dropped from a L-1011 aircraft over the Pacific Ocean at an altitude of 39,000 feet, about 100 miles northwest of Vandenberg Air Force Base, Calif. The rocket placed IRIS into a sun-synchronous polar orbit that will allow it to make almost continuous solar observations during its two-year mission.

The L-1011 crew released Pegasus at 10:27 p.m. The first stage ignited five seconds later to carry IRIS into space. IRIS successfully separated from the third stage of the Pegasus rocket at 10:40 p.m. At 11:05 p.m., the IRIS team confirmed the spacecraft had successfully deployed its solar arrays, has power and has acquired the sun, indications that all systems are operating as expected.

"Now that IRIS is in orbit, we can begin our 30-day engineering checkout followed by a 30-day science checkout and calibration period,” said IRIS project manager Gary Kushner of the Lockheed Martin Solar andAtmospheric Laboratory in Palo Alto, Calif. During this phase, the team will check image quality and perform calibrations and other tests to ensure a successful mission. Following the 60-day checkout period, IRIS will start science observations.

NASA's Explorer Program at Goddard Space Flight Center in Greenbelt, Md., provides overall management of the IRIS mission. The principal investigator institution is Lockheed Martin Space Systems Advanced Technology Center. NASA's Ames Research Center will perform ground commanding and flight operations and receive science data and spacecraft telemetry.

The Smithsonian Astrophysical Observatory designed the IRIS telescope. The Norwegian Space Centre and NASA's Near Earth Network provide the ground stations using antennas at Svalbard, Norway; Fairbanks, Alaska; McMurdo, Antarctica; and Wallops Island, Va.

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