Asteroids: the little ones are the killers

Stan Beer
Sunday, 11 March 2007 17:38

Science - Space

In 2005, the US Congress passed a bill authorizing the National Aeronautics and Space Administration to go and look for potentially hazardous small asteroids 140 meters or larger in diameter. The problem is that the bill didn't provide the US$1 billion that NASA reckons it will need to fund such a project.

Apparently there are about 100,000 of the little devils floating around in space and a couple of dozen or so are on trajectories that could possibly pose a threat to Earth. An asteroid that in 1908 exploded over the Tungunska forest in Siberia, believed to be just 60 meters in diameter, levelled 2000 square kilometers of woodlands.

At present, NASA has not even scratched the surface of initiating the necessary work needed to identify all the small potential killers of the scale of Tunguska.

The ominous sounding Planetary Defense Conference, held March 5-8 in Washington D.C., is set to produce a new white paper to follow up the 2004 effort titled Protecting Earth from Asteroids. The aim is to inject urgency and gain the political will to fund the effort needed to weed out the smaller rogue asteroids.

The large asteroids with diameters measured in kilometers are not thought to be dangerous because the probability is so small that any are on a collision course with the Earth in the foreseeable future. However, there are so many unidentified smaller asteroids, that there is a statistically significant risk that some could be a disaster in the making for our planet.

While large asteroids are believed to have hit the Earth in past epochs, one such impact perhaps leading to the extinction of the dinosaurs, smaller strikes like the Tunguska event are believed to happen far more frequently. Such strikes could result in the death of millions of people, creating devastation on a scale equivalent to several large nuclear bombs.