XCOR's EZ-Rocket is an almost comically tiny aircraft, but when tethered to the asphalt for a test, it lunges fiercely against its lead. The engines, no bigger than 40-ounce beer bottles, generate enough thrust to push the plane to Mach 1, if the airframe could handle it, which it can't. Before lighting up the EZ-Rocket for a test run on the tarmac at Mojave Airport, the crew conducts a pretest in the hangar. It takes a while because Clague is meticulously ticking off 278 interim steps on a comprehensive checklist: helium loading, liquid-oxygen loading, rollout, propulsion preflight. "If you do everything on here," says Doug Jones, one of the company's founders, who has drifted over to look at the list, "the test can't not work."