An Orbital Sciences Pegasus XL has successfully launched a NASA satellite into low Earth orbit (LEO).

A Lockheed L-1011 carrier aircraft lifted off on 27 June from Vandenberg AFB, California, and carried the Pegasus XL to 39,000ft, where the rocket was launched.

Pegasus is currently the only operational air-launch system, taking advantage of the L-1011's speed and altitude to get above the thickest part of the atmosphere. The flight profile also lends the rocket additional energy, allowing the Pegasus XL to launch greater payloads than an equivalent ground-launched vehicle.

The flight marks the 42nd for Pegasus, according to Flightglobal Ascend's database.

Orbital Sciences is also building a much larger air-launched rocket for Stratolaunch, capable of lofting 6,120kg (13,500lb) into orbit from a unique one-off carrier aircraft.

ATK Orion-model solid-fuel motors power all three stages of Pegasus.

The satellite, the Interface Region Imaging Spectograph (IRIS), is designed to study the surface of the sun.

Orbital Sciences was not available for immediate comment.

Source: Flight International