A Pegasus Rocket launched from Orbital's airplane "Stargazer"

A Pegasus Rocket launched from Orbital’s airplane “Stargazer”

Tonight Orbital Sciences Corporation is launching a Pegasus rocket from Vandenberg Airforce Base in California (which is a sentimental, um, missile base for me since my grandfather was a workman there back in the ‘50s).  Orbital is one of those vaunted private companies which is reaching for space as the government defunds NASA, although, truth be told, the corporation seems to concentrate on launching satellites and building rockets for the government so it might not be too different from the classical aerospace companies which have been interwoven with the nation’s Space/Defense programs since back when grandpa was painting missile silos. The apex of Orbital’s ambition was to build a spaceplane to replace the space shuttle, but their proposal was not selected by NASA and they are winding down their efforts to build a crewed vehicle.

The IRIS solar observatory satellite (NASA)

The IRIS solar observatory satellite (NASA)

Actually the Pegasus rocket is launched from a high altitude airplane which is launched from Vandenberg.  This technology was developed during the cold war for interception (i.e. shooting down enemy spy satellites) but tonight it finds a higher calling: the rocket will be launching a small satellite named IRIS into orbit.  IRIS stands for Interface Region Imaging Spectrograph.  The satellite is a small ultraviolet solar observatory designed to study the mysterious chromosphere of the sun—the second of three layers of the sun’s atmosphere which, perplexingly, is much hotter than the region beneath it.  You can look at this old post for a proposal about why this is so–the answer probably involves solar tornadoes (IRIS will be able to tell us if this solution is correct).

o-CHROMOSPHERE-OF-SUN-570

If you are turning in around 10:20- 10:30 EST you can watch the launch at this link (probably).  Go IRIS!  It’s exciting to have another robot spacecraft monitoring our star!