The 40-foot-long, 4-foot-wide rocket loomed over the quiet suburb of Alameda, Calif., on the morning of Jan. 18, near the Pottery Barn Outlet. A handful of engineers and metal wrenchers got to work early, setting up the rocket and connecting it to a mess of electronics and tubes. The device stood up straight, with the help of some black metal scaffolding. Its bottom third gleamed aluminum; the rest, actor-teeth white. Over the course of the day, the team pumped in various gases and liquids to prepare the rocket's valves, chambers, and other components for a crucial test.

Shortly after midnight, the rocket was ready for an exercise called a cold flow, meant to ensure that its propellant tanks can handle liquid fuel. Once the team had filled the rocket, taken the needed measurements, and checked for leaks, they simply evacuated the machine by releasing huge volumes of liquid nitrogen into the air.