Software on Tucker’s computer compares his fresh images with maps of known stars and asteroids. This makes it easier for him to pinpoint potential new objects, but it still takes him about two hours to eyeball each morning’s photos. The drudgery is punctuated by occasional moments of excitement. “When I think I see something new, I go to the Minor Planet Center’s Web site and enter in the object’s coordinates,” he says. “If the site tells me ‘No known object,’ that’s when I start getting excited.” Once researchers at the MPC independently confirm his find, he can celebrate—and add another notch to his asteroid belt. It takes observations on at least three different nights to calculate an approximate orbit, but to really nail down an orbit so that the asteroid’s position can be predicted accurately for years in advance requires dozens of observations conducted over several years.
Although large, professionally conducted surveys like the Catalina Sky Survey, which uses telescopes in Arizona and Australia, and LINEAR in Socorro, New Mexico, have made the majority of Spaceguard finds, amateurs fill a critical role. “The surveys are sweeping the sky in a very systematic way, but amateurs can look outside of the survey paths, and they also have the flexibility to look closely at small patches of sky,” Chesley says. The Minor Planet Center at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, which vets every reported asteroid discovery in the world, welcomes amateur finds. Any observatory, private or public, that passes the MPC’s initial test—recording telescope images of well-known asteroids and measuring their positions correctly—is assigned a site code (Dyvig’s is 918). Nearly a thousand amateurs have these codes, which enable them to submit discoveries for official verification. The amateur record holder is a Japanese engineering professor, Takao Kobayashi, who has a staggering 2,392 numbered asteroids to his credit.
While several members of Congress, including Rohrabacher, contend that a national prize program would help encourage the best amateur asteroid hunters, enthusiasts like Dyvig and Tucker don’t need a financial incentive. Their night job is its own reward. “Finding an asteroid or comet is an incredible experience,” Tucker says. “Imagine all the endorphins in your brain being released at once!” Chesley agrees: “The publicity that would go along with a prize might energize the amateur community and keep it more vibrant, but these people aren’t motivated by money.” All the same, Rohrabacher thinks awards would draw more Americans to the task of asteroid finding. He cites the success of the $10 million Ansari X-Prize, which reinvigorated the personal spaceflight industry and inspired the first private rocket ship into space. “Prizes are a great way of bringing about change,” he says. “They create competition, and there’s no cost unless someone succeeds.”
If an amateur or survey telescope did spot a potentially dangerous asteroid, there would be no need to build bunkers or mount Armageddon-style rescue missions right away. With only a few observations to feed into their calculations, the early estimates by scientists of an asteroid’s future orbit have huge uncertainties. Later observations that refine the predicted trajectory of worrisome rocks have always—at least so far—shown there’s no cause for alarm. For example, the asteroid Apophis, which initially seemed headed our way in 2029, now seems destined to miss Earth by thousands of miles, but there is still a 1-in-45,000 chance of an impact on April 13, 2036. “You can’t just discover something and say, ‘Oh, it’s going to hit us in 30 years,’” Chesley says. On the other hand, if an asteroid hit ever does appear to be in the cards, we will probably need many years to deflect it off course. The sooner we try to deflect an asteroid (perhaps by using the gravitational pull of a spacecraft to yank it onto a new course) the easier it will be, which is why Spaceguard is trying to catalog everything big enough to be a threat.
Regardless of how crucial Spaceguard’s mission turns out to be, the same march of technology that has made amateurs like Dyvig and Tucker so valuable to the asteroid hunt may soon make them obsolete. Instruments like the 8.4-meter Large Synoptic Survey Telescope, slated to begin operation in 2014, will use massive computer power to carry out continuous scans of sky for near-Earth objects, leaving ever fewer patches for amateurs to focus on. But Tucker isn’t deterred. His fellow amateurs, he points out, are starting to make an impact in other areas, like monitoring the fluctuations of variable stars and investigating powerful cosmic explosions known as gamma-ray bursts: “Something else is going to come along—and we’ll be able to contribute.”