On Tuesday, an Air Force B-52 bomber is scheduled to take off from Edwards Air Force Base in California. Under its wing will be the closest thing in the world to a hypersonic missile. The plane will soar over the Pacific Ocean, ascend to 50,000 feet, and then let loose the 26-foot-long experimental missile. If all goes well for the military’s flight test, the missile will accelerate past Mach 5, rush more than 300 miles in less than five minutes, and usher in a new chapter in high-speed warfare. If it fails — and the last two tests of this X-51A Waverider have fallen short — then the Pentagon will have sent something on the order of $300 million to the bottom of the Pacific.
The U.S. military is scrambling to find a method for striking targets hundreds, even thousands, of miles away in a matter of minutes. But the Pentagon’s options for this so-called “prompt global strike” mission are all problematic. It can retrofit once-nuclear Intercontinental Ballistic Missiles, or ICBMs, with conventional warheads. Such launches would resemble atomic first-strikes, though, and could trigger World War III. Option two is to go with something like the X-51A — a cruise missile than can travel seven or eight times faster than anything presently in the American arsenal. Mastering the aeronautical engineering, materials science, and fluid dynamics needed to build such a hypersonic weapon have not been easy, however.