Within decades, the world’s leaders may be forced to grapple
with a momentous decision: whether and how to deflect an
incoming object. Few experts are giving this much thought, says
astronomer David Morrison of NASA’s Ames Research Center: “The
number would roughly staff a couple shifts at a McDonald’s.” Lu,
the former astronaut, is one. Now an executive at Google, he is
helping design a massive database for a successor to Pan-STARRS,
the Large Synoptic Survey Telescope, which will scrutinize the
sky in even more detail starting in 2014. Lu is also the
coauthor of a scheme for using a spacecraft to coax an
earthbound asteroid off its dangerous path. “We were originally
thinking about how you would land on an asteroid and push it,”
he says. "But that doesn't work well." If the surface is
crumbly, the lander might skid off. Moreover, asteroids twirl
through space. "If you're pushing and the thing is rotating, the
pushing just cancels out," Lu says. Then he and Stanley Love, a
fellow astronaut, realized pulling