The U.S. airspace is getting busier-and not just with more airplanes. In addition to some 70,000 aircraft traversing the National Airspace System (NAS) each day, commercial enterprises are rapidly introducing a widening variety of new space vehicles and launchers into it. And more are on the way, ranging from rockets carrying supplies to the International Space Station to vehicles for space tourism. In 2015, 22 of the world's 86 orbital launches were commercial. And today, vertical launch vehicles with "fly-back" boosters that return to Earth autonomously, launchers that take off and land on runways, and captive-carry concepts-where an aircraft carries a space vehicle to a higher altitude for launch-are operational or in testing and production.
展开▼
