Dodged the bullet again - or rather, dodged the asteroid. It really is time for the advanced nations to organize an anti-asteroid defense.

The asteroid - named 2009 DD45 - passed Earth early Monday (2 March 2009) 48,800 miles above Tahiti. It measured between 69 feet and 154 feet across, about as big as the one that crashed near Tunguska, Siberia, in 1908 and leveled 830 square miles of forest. That's a 32-mile wide circle.

Encounters with asteroids are rare, and the bigger the asteroid, the more rare it is. Most of our planet is open space (70 percent is ocean), so a collision with a small object is unlikely to do much damage. Small objects explode high in the atmosphere several times a year.

But larger objects can reach the ground. The Planetary Society, which is beating the drums for an asteroid defense, estimates that a "Tunguska Event" could cause at least some human casualties roughly every 300 years. A troubling scenario.

Space-capable nations should agree to maintain suitable rockets on standby for quick launch against intruders like 2009 DD45. It wouldn't cost much, and might be one of those rare instances where we can work with partners, such as Russia, on a mutually beneficial project.