The Pegasus Rocket

This is the Pegasus XL that will launch SWAS on Dec 2nd 1998. The Pegasus is carried up to 40,000 feet on the underneath of an L1011 jet aircraft, where it is released at an airspeed of Mach 0.8. The three-stage solid-propellant booster system then ignites to take the spacecraft into orbit.

This is the rocket that will be used to launch WIRE

You can see the separate stages in this picture