sentences:  Aerojet was contracted by NASA to build the main engine of the Apollo Command/Service Module, and the Space Shuttle Orbital Maneuvering System.In a letter to Frank Malina, von Kármán ranked Parsons first in a list of figures he viewed as most important to modern rocketry and the foundation of the American space program.According to Richard Metzger, Wernher von Braun—who was nicknamed "The Father of Rocket Science"—once argued that Parsons was more worthy of this moniker.