NASA's IRIS Mission Delayed

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NASA's mission to study the lowest layers of the sun's atmosphere, though hobbled temporarily by a massive power outage on Earth, is expected to launch June 27 and soon yield new information about the source of the sun's ultraviolet emission and its influence on the Earth's climate and many of the satellites we rely on.

The launch of NASA's Interface Region Imaging Spectrograph (IRIS) satellite was delayed by a day due to a massive power outage at the launch site at California's Vandenberg Air Force Base. NASA officials believe they will be able to restore power to facilities affected by the power outage in time for the rescheduled launch Thursday evening.

The 400-pound, seven-foot-long satellite is loaded aboard a Pegasus XL rocket that will be launched from an Orbital Sciences L-1011 aircraft. IRIS will fly around Earth, crossing almost directly over the poles, to study in detail the lowest layers of the sun's atmosphere, called the interface region. Understanding how energy -- which helps heat the upper layer of the sun's atmosphere, the corona -- travels through this region is the main goal of the mission. IRIS will also help scientists gain knowledge about the impact of radiation and solar particles on satellites, space weather and planet Earth.

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The interface region affects many aspects of near-Earth space, including particles that fill the solar system. It's also the source of the sun's ultraviolet emission, which influences Earth's climate. Explosions in the corona can cause radiation and solar particles to travel toward Earth, affecting satellites, and resulting in power grid failures and GPS service disruptions. Studying solar eruptions can help scientists forecast such space weather.

"This region is crucial for understanding how the corona gets so hot. For the first time, we will have the capability to observe it at fundamental physical scale sizes and see details that have previously been hidden," Joe Davila, IRIS project scientist at NASA's Goddard Space Flight Center, said in a written statement.

The two-year mission consists of a single instrument: an ultraviolet telescope combined with an imaging spectrograph. IRIS will orbit the Earth, using the telescope to capture high-resolution images and spectra, a kind of data. NASA said the satellite will collect data about 1% of the sun at a time, enabling scientists to see details as small as 150 miles across. A new image will be captured every five to ten seconds, and spectra about every one to two seconds.

NASA's Ames Research Center will use 3-D numerical modeling on supercomputers, such as Pleiades, to interpret the IRIS data. Science teams at Lockheed Martin and the University of Oslo in Norway have spent the last year creating and refining advanced computer models for this mission. The IRIS Mission Operations Center, located within the Ames Research Center, will send commands to IRIS and monitor telemetry, including temperatures on the satellite, the direction it's pointing in, and information about its onboard computers. Automated tools will alert flight controllers if IRIS is experiencing problems when they're not at the operations center.

IRIS will join a host of other solar observatories aimed at studying how the solar atmosphere works and impacts the Earth. NASA's Solar Dynamics Observatory (SDO) mission and the combined NASA/Japan Aerospace Exploration Agency (JAXA) Hinode mission monitor the solar surface and outer atmosphere, while IRIS will focus on the region in between.