Our fascination with the prospect of asteroids smashing into the Earth is as deep as the craters that can result from such cosmic fireballs. Think of all the movies Hollywood has made, from little-seen B flicks such as A Fire in the Sky to campy cult classics such as Night of the Comet to scientifically shaky blockbusters such as Meteor and Armageddon.
The 1990s was also awash with news of rocky passersby such as the Hale-Bopp Comet and the Comet Shoemaker-Levy 9 that unleashed fragments up to two kilometers wide upon Jupiter in 1994.
Once dismissed as the province of fringe cult groups, the fear of what astronomers call "impact events" turns out, with improved satellite and telescopic monitoring, to not be so irrational after all.
Pan-STARRS on patrol
The latest and most ambitious to detect 'near-Earth objects' (NEOs) is the Panoramic Survey Telescope and Rapid Response System, or Pan-STARRS.
A joint venture of the University of Hawaii, a number of other schools and the US Air Force, Pan-STARRS is today testing a telescope mounted with the finest digital camera in existence, which boasts a resolution of 1.4 billion pixels.
When Pan-STARRS is fully operational several years from now, it will have 4 telescopes, each with a 1.4-gigapixel camera.
That will give Pan-STARRS a wider, faster and more powerful view into space, and enable it to meet its mandate of tracking virtually all NEOs larger than 300 meters in diameter as well as many smaller NEOs.
It'll have plenty to see. About once a year, an asteroid between 5-10 meters in diameter explodes in the Earth's upper atmosphere, releasing as much energy as the atomic bomb used at Hiroshima. And it doesn't take a big one to slip through and cause a lot of damage; certainly that 300-meter line has been crossed before, to devastating effect.. The asteroid behind 1908's Tunguska Event created an explosion equivalent to 10-15 megatons of TNT (about 1,000 times the Hiroshima bomb), knocking over an estimated 80 million trees in Siberia and causing an earthquake that's estimated to have measured a 5.0 on the Richter scale (uninvented at that point). It was only about 50 meters in diameter. And we are due for another one within 200 years, according to the late astronomer Eugene Shoemaker.
With just a single telescope, Pan-STARRS already generates 1.4 terabytes of raw image data nightly. Compressing, storing and crunching that data in an economical fashion turns out to be a feat of database engineering as impressive as the collection process.
Rather than turning to an expensive supercomputer equipped with hundreds or thousands of processors, Pan-STARRS will use a cluster of 50 PC servers connected to 1.1 petabytes of disk storage via fast Infiniband networking gear, according to Alex Szalay, a physics and astronomy professor at Johns Hopkins University and one of the architects of Pan-STARRS' database.
And rather than using a database management program better-known for ultra-large data warehouses, such as IBM's DB2, TeraData, or Oracle Database, Pan-STARRS will use Microsoft's just-released SQL Server 2008.