that kind of range. Less has been said about their precision, though Strider said the Army’s Advanced Hypersonic Weapon
“is showing a lot of capability to be able to get where it’s supposed to get and hit with a lot of energy. … In our upcoming tests we’ll be testing those bounds more and looking at what the vehicle really is capa- ble of as far as maneuverability.”
Some defense analysts are unconvinced that the United States needs a hypersonic strike and are skeptical of some technical claims made about hypersonic weapons, pointing out that there are other ways to hit fleeting targets, get into denied areas or strike a rogue nuclear facility—ways that cost less, and risk less.
WHY GO HYPERSONIC? Research on hypersonic flight goes back to the 1960s, but it has been technically challenging to achieve. At hypersonic speeds, the air molecules around the flight vehicle start to change, breaking apart or gaining a charge in a process called ionization. Tis subjects the hyper- sonic vehicle to tremendous stresses. Spacecraft, and ballistic missiles, spend most of their flight out of the atmosphere, free of the heat, pressure and friction, while hypersonic vehicles have to push through the atmosphere. “Te thermal protection system for the hypersonic weapon is one of the key, very key, tech- nologies that have to be in place because the hypersonic weapon is pretty much in the atmosphere through its flight; it gets temperatures in excess of 2,000 degrees for quite a few minutes,” said Strider.
Hypersonic flight has several applications. A reusable hypersonic airplane (of the
“two hours from Beijing to London” vari- ety) is the most distant, though NASA and the Defense Advanced Research Projects Agency have both explored preliminary steps; it’s weapons that are
capable of hypersonic speeds that DOD is actively pursuing. These come in several varieties, including hypersonic cruise missiles and boost-glide vehicles. Te former are powered during their flight by an attached engine; the latter are unpowered after launch and, as the name suggests, glide to their destination.
Te U.S. military began pursuing hyper- sonic weapons in earnest under the Conventional Prompt Global Strike program in 2007. Te program sought to achieve a non-nuclear strike anywhere around the globe within an hour. Now, a prompt global strike also appears useful as part of a package of options to coun- ter anti-access and area denial measures. As concern grows about China’s efforts to close off what it considers its part of the Pacific, a weapon that could fly undetected into the denied area while the launch plat- form stays well outside becomes more attractive to U.S. military planners.
Te Army’s Advanced Hypersonic Weapon demonstrator, tested in 2011 and 2014, relied on boost-glide technology. Rock- ets launch—boost—the glide vehicle to a high altitude, giving it enough speed and energy to reach its target. Te glide vehi- cle then curves back toward the Earth’s surface, and glides or skips along the atmosphere without power for the remain- der of its trajectory. (Tough “glide” might suggest gentle motion, the vehicle is tear- ing through the atmosphere at Mach 5 or faster.)
The U.S. Army Aviation and Missile Research, Development and Engineering Center, in Huntsville, Alabama, devel- oped the thermal protection system. Te Army team collaborated with a number of national laboratories on the launcher and glide vehicle design, and refined it in wind tunnels where vehicle forces were measured at hypersonic speeds.
“These very
breathless technical claims about hypersonic weapons being these silver bullets, without the question mark, that can do everything— at the very least the jury is still out.
”
CHANGING THE GAME? Hypersonics have been spoken of as game- changers (whether because of their speed or their radar-evading low flight profile), though opinions vary across the defense community as to whether current hyper- sonic technology is advanced enough to be revolutionary. In the “yes” column is Strider. “I see it as a game changer. I’d say there’s very few mechanisms today that could stop a hypersonic weapon.”
Whether they change the game or are an incremental shift is, to some extent, a moot point by now: China is testing hyperson- ics, so is Russia, and therefore, so is the United States. “I do think for better or
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