A 2005 congressional mandate requires NASA to record 90% of the 20,000+ near Earth objects (NEOs) sized 140+ meters in diameter. NASA has until 2020 to catalog them but lacks time and funding. Ah, the politics of doomsday prevention.
A recent article in Nature notes the political and logistical difficulties inherent in logging those NEOs that could hit Earth. Scientists are weighing several options, including building a NEO-detection telescope with an orbit similar to that of Venus and creating a panel to catalog the position and number of NEOs. In any case, funding asteroid detection and prevention is a collective action snafu on both an international and domestic level:
Launching missions to track or deflect all potential asteroid threats will be prohibitively expensive, but even a small probability of regional or global devastation may not be politically palatable. [...] One solution from the panel is to increase the amount that the United States invests in NEO detection and tracking from the current $5.5 million a year. The panel may also recommend the launch of a [$600 million] survey telescope into a solar orbit similar to that of Venus. It would orbit faster than Earth and, looking outwards, would see asteroids in Earth-crossing orbits more often than would ground-based instruments [...]
Owing to a 2008 law passed by Congress, the White House Office of Science and Technology Policy has until 15 October to decide which agency will be responsible for protecting the planet from an asteroid strike. Members of the task force say NASA expects to be given part or all of that responsibility. To meet it, the panel discussed the creation of a Planetary Protection Coordination Office (PPCO) within NASA, with an annual budget of $250 million–$300 million [...] The PPCO would also challenge other countries to fund defence against asteroids, perhaps through the United Nations. Canada already plans to launch the NEO Survey Satellite in 2011, and Germany's AsteroidFinder is slated for launch in 2012, but neither is expected to come close to the NEO-logging goal by 2020.
Obviously, there are plenty of earthbound problems for Congress to deal with, but the notion of routinely earmarking taxpayer money towards space rock-induced global extinction prevention is just plain surreal. Funding a giant space drill, now that's a plan voters can wrap their heads around.