The California Institute of Technology's Jet Propulsion Laboratory, which developed the spacecraft, insisted that the only licensed Sojourner toy "be very accurate," says Joan Horvath, the lab's business alliance manager, who came up with the idea for a Mars mission toy. Working from blueprints, Hippely and his team also consulted the project's engineers. "The most fun thing was going down to their lab, where the spacecraft was being assembled," he reports. "We got to dress up in those white suits." Although deadlines prevented the team from seeing the finished spacecraft ("Some things we just had to guess at," he says), Hippely is proudest of getting the rover's "rocker-bogie" six-wheel suspension right. "The wheels move up and down," he says. "You can go over rough terrain like the real thing."
If you can find the toy. The lab's employee shop received 1,500: "They were gone in 20 minutes," says Horvath. A Mattel source says the company hopes to ship "hundreds of thousands" by next week. Hippely thinks the wait is worth it. "We were able to put more working features in than we normally do in a Hot Wheels," he says. How come? Says Hippely: "I got lucky."