Dulles, Va.-based Orbital Sciences Corp. said July 1 that it has booked an order to launch NASA’s Interface Region Imaging Spectrograph (IRIS) spacecraft in 2012 aboard a Pegasus XL rocket from Vandenberg Air Force Base, Calif.

IRIS is a NASA Small Explorer mission built by Lockheed Martin Space Systems’ Palo Alto, Calif.-based Advanced Technology Center to measure the sun’s flow of energy through the dynamic region in the solar corona and heliosphere. The $105 million mission is expected to help scientists better understand the effects of solar energy release processes on Earth.

The 2012 launch will be the air-launched Pegasus rocket’s 45th mission since its 1990 debut and the second Pegasus launch scheduled for that year. NASA’s Nuclear Spectroscope Telescope Array — a Small Explorer spacecraft built by Orbital — is scheduled to launch in February 2012.