be launched by a Pegasus XL rocket, and had been designed so as to fit within the Pegasus XL rocket constraints. With the IXPE launch removed from the Pegasus XL rocket, there are currently (as of 12 October 2019, after the launch of ICON) no space launch missions announced for the Pegasus XL rocket. The future (under construction as of 2019) NASA Explorer program mission Polarimeter to Unify the Corona and Heliosphere (PUNCH) was planned to be launched by Pegasus XL; but then NASA decided to merge the launches of PUNCH and another Explorer mission, Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS) (also under construction as of 2019). These two space missions, consisting of 6 satellites in total, are to be launched by one launch vehicle. It is expected that a larger launcher will be chosen for this dual mission launch. Northrop has two Pegasus XL's remaining in its inventory. It is looking for customers for those rockets. Northrop does not plan on retiring the Pegasus XL rocket as of October 2019. Launch profile In a Pegasus launch, the carrier aircraft takes off from a runway with support and checkout facilities. Such locations have included Kennedy Space Center / Cape Canaveral Air Force Station, Florida; Vandenberg Air Force Base and Dryden Flight Research Center, California; Wallops Flight Facility, Virginia; Kwajalein Range in the Pacific Ocean, and the Canary Islands in the Atlantic Ocean. Orbital offers launches from Alcantara, Brazil, but no known customers have performed any. Upon reaching a predetermined staging time, location, and velocity the aircraft releases the Pegasus. After five seconds of free-fall, the first stage ignites and the vehicle pitches up. The 45-degree delta wing (of carbon composite construction and double-wedge airfoil) aids pitch-up and provides some lift. The tail fins provide steering for first-stage flight, as the Orion 50S motor does not have a thrust-vectoring nozzle. Approximately 1 minute and 17 seconds later, the Orion 50S motor burns out. The vehicle is at over 200,000 feet (61 km) in altitude and hypersonic speed. The first stage falls away, taking the wing and tail surfaces, and the second stage ignites. The Orion 50 burns for approximately 1 minute and 18 seconds. Attitude control is by thrust vectoring the Orion 50 motor around two axes, pitch and yaw; roll control is provided by nitrogen thrusters on the third stage. Midway through second-stage flight, the launcher has reached