Two years ago last Wednesday—June 21, 2004—the space world’s attention was focused on a small airport in the desolate high desert 150 kilometers from Los Angeles. Or, more precisely, in the skies above Mojave Airport, as a small winged spacecraft, built using lightweight composites and powered by an engine that effectively used laughing gas and rubber as propellants, became the first privately-developed manned vehicle to cross the 100-kilometer boundary that serves as the demarcation line for space. From a technical standpoint, that achievement was not that impressive: governments have been sending people into orbit, and not just brief suborbital hops,...