Jet packs began to appear in science fiction long before science made them a reality. Toward the end of WWII, scientists began working seriously to develop a wearable propulsion device that would enable a single user to fly. Now a reality, jet packs are prohibitively expensive and difficult to control. Because jet pack flights are brief, most do not achieve the minimum altitude necessary to deploy a parachute in the event of a breakdown. What is currently the only practical use for jet packs? Discuss