Before NASA put people on the moon and robots on Mars, it was the National Advisory Committee for Aeronautics (NACA), a body created by a 1915 act of Congress to make sure the country that invented flight could regain the technical edge it had lost to Europe. Even after space was folded into its mission and NACA became NASA, it kept "aeronautics" in the name, and for years produced staggeringly bizarre, alien-looking aircraft. These were the X-Planes, and NASA's new budget proposal wants to bring them back.

The most iconic of the X-Planes is perhaps the most straightforward: the bright orange X-1, piloted by Chuck Yeager, which broke the sound barrier in 1947. It currently hangs inside the Smithsonian's National Air and Space Museum. NASA's X-15 hit a top speed of mach 6 and explored flight at the edge of space.