The Defense Advanced Research Projects Agency said Friday it will host a so-called Proposers' Day on Aug. 14 to lay out technical areas for which proposals are being sought.
DARPA has tested highly experimental versions of a rocket-launched unmanned glider designed to fly at speeds 20 times the speed of sound, or Mach 20. The goal is to give the U.S. a defense capability of reaching any spot on Earth in an hour.
But such aircraft have to endure blast-furnace heat and require extraordinary controls.
The last test launch from California ended with the glider's skin peeling away.