Cosmic Crossfire

Dawn  over Chelyabinsk, 15 February 2013

An asteroid the size of a city block passed inside the geosynchronous satellite orbit the other day, suffering significant gravitational deflection.

The almost simultaneous - and unexpected - arrival of a much smaller piece of space debris - a trifling seventeen metres across - would therefore have given no particular cause for concern except that this ten ton pebble scored a direct hit, and almost touched down. The big one which missed flew in from the south, the much smaller object came in at dawn from the east. Travelling at 64,000km/h, it punched through the atmosphere then fireballed across the Urals, giving the citizenry of Chelyabinsk a day to remember, with over a thousand casualties and buildings damaged by the thermal shockwave of the object breaking up and being virtually incinerated by the security blanket of the atmosphere. This was the largest impact in over a century, twenty times the impact power of Hiroshima. The much larger so-called Tunguska event in 1908 flattened vast tracts of Siberian wilderness and nobody important went to have a look until ten years later.

Such events always give me the what-ifs. These events are not uncommon. What if our ancestors, looking into night skies untroubled by light pollution, once in a while, saw a fireball falling to earth. It would have sent them fleeing, terror-stricken, to the shelter of their caves. Perhaps they believed that they had inadvertently angered a malevolent and vengeful deity who was announcing his intention for retribution. What if the meteors had been reversed and the bigger one had struck? In all probability, the damage would not have come close to what Hollywood describes as an 'extinction event'. Yet, we are at the mercy of random gravitational deflections and with all the statistical posturing and estimates of damage limitation, we are as ill-prepared psychologically now as we were during the Stone Age. Understanding the reasons for our destruction avails us little in the face of its reality. In the movie 'Deep Impact' which describes the possibility of such a scenario, I have often reflected on how people's behaviour might change in the face of certain annihilation. On the one hand, there would be the rapists, looters and pillagers, all moral restraint swept aside. On the other, there would be those who are able to reach inside of themselves for their personal Zen, perhaps experiencing almost mystic, revelatory clarity, as Ludwig Wittgenstein apparently did, sitting in the middle of a First World War battlefield, shells raining down, writing his ideas in a notebook.

 'Deep Impact' 1998. Hope survives.

There are over nine thousand known candidates for near-earth impact. One day, we or our descendants might not escape. But, perhaps, not today. Our species likes the idea of continuity, and the thought of its disruption by an inconsiderate visitation from a stray cosmic pebble or the Angel of Death is uncomfortable.