Aerospace

Secretive X-37B Military Space Plane Preps for Another Mystery Mission

The United States Air Force's X-37B space plane will launch on its fourth mystery mission next month. The unmanned X-37B, which looks like a miniature version of NASA's now-retired space shuttle orbiter, is scheduled to blast off atop a United Launch Alliance Atlas V rocket from Florida's Cape Canaveral Air Force Station on May 20.