VANDENBERG ABF, Calif. - The Orbital Sciences L-1011 aircraft called "Stargazer" arrives at Vandenberg Air Force Base for the upcoming launch of the company's Pegasus XL rocket lifting NASA's IRIS solar observatory into orbit. The aircraft will carry the winged rocket to an altitude of 39,000 feet before releasing the Pegasus so its own motors can ignite to send the IRIS into space. The L-1011 is a modified airliner equipped to hold the Pegasus under its body safely. IRIS, short for Interface Region Imaging Spectrograph, is being prepared for launch from Vandenberg June 26. IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. IRIS fills a crucial gap in our ability to advance studies of the sun-to-Earth connection by tracing the flow of energy and plasma through the foundation of the corona and the region around the sun known as the heliosphere. Photo credit: VAFB/Randy Beaudoin KSC-2013-2745