THE ANSWER: In Iron Man, Tony Stark's suit is incredibly powerful, a wearable weapon system that can hurl cars and outmaneuver jet fighters. In reality, it is the synthesis of two technologies: the jetpack and the exoskeleton, which is the more promising of the two. In terms of exoskeletons, no one will be bench-pressing Buicks anytime soon, but a number of systems already exist as assistive or rehabilitative medical devices. Companies such as Argo Medical Technologies and Ekso Bionics offer motorized devices targeted to the disabled that can essentially walk for their wearers, allowing users a more versatile alternative to wheelchairs. There could be other applications for exoskeletons, too. At NASA, researchers are working to incorporate them into space suits. They have developed one that could eventually allow astronauts to hike across Mars for long stretches, loaded with gear, while expending little energy.