text: But the Bell Rocket Belt now gathers dust in the Smithsonian's Air and Space Museum. Its exceedingly short flight time, 20 seconds, was both impractical and unsafe. Unlike airplanes, jet packs cannot land gracefully when the power fails. Soon even the comic-book heroes of the future had begun to do without jet packs.Several jet packs were indeed under development by the late 1950s. One of them, called the Jump Belt, used compressed nitrogen. Another, the Aerojet, used compressed hydrogen peroxide. A few years later, Bell Aerospace's Rocket Belt, also using hydrogen peroxide, seemed the most promising and briefly took James Bond off the ground in "Thunderball."