THE ASTEROIDS ARE COMING!
HOW TO SURVIVE: ARMAGEDDON
What is the best advice for staying alive when a flaming ball of interstellar debris plummets into the Earth? We’re going to have to believe in a divine author and pray, pray, and pray some more. Never fear though! Becky Martin has an asteroid impact survival guide.
NASA chief Charles Bolden recently gave some advice of what to do if there was an impending asteroid collision. His guidance was simple: we should “pray”. Now there’s a cheerful thought. But just how likely is this doomsday scenario and what – apart from praying – can we do to survive?
It’s a lottery and there’s a good chance we’ll lose
Our planet is being continually pelted by solar system debris. Yet we are rarely aware of this daily galactic pummelling: most objects fizzle away high in the atmosphere where they are too distant for their shock waves to reach us. (The exceptions are the ‘falling stars’ that we wish upon – though these aren’t actually stars but fiery lumps of space rock or metal that vaporise as they plummet through our atmosphere.) Sometimes, however, projectiles can survive their journey through our atmosphere and reach the ground – at which point they are termed ‘meteorites’. It is estimated that over 500 meteorites reach the surface of the Earth in this way every year. In the world of interstellar projectiles, it’s survival of the fittest, as only the strongest iron rocks reach the Earth in one piece. So, when have asteroids really made an impact here on Earth? Well, how about the Tunguska
event of 1908? Tunguska was an ‘airburst’ event, during which the asteroid or comet disintegrated in the lower atmosphere. Although there was no collision, it created a shockwave that was sufficient to fell trees across an area of 1000 km2 (250,000 acres) and the blast yield has been estimated at 10-20 megatons – 1,000 times more powerful than the nuclear bomb used over Nagasaki in the Second World War. But we should perhaps be more concerned about a recurrence of whatever caused the 180 metre wide Chicxulub crater over 65 million
years ago, which coincided with the start of the Cretaceous-Palaeogene extinction event. The Chicxulub meteorite disrupted the global ecosystem and wiped out half the species on Earth, including the dinosaurs (although thankfully it ultimately resulted in our dominance in the food chain). Unlike the reptiles, we have large brains and a space programme and therefore really shouldn’t succumb to the same fate. (Well, that’s what we’re hoping.) So are we likely to experience an apocalyptic impact in the near future? The NASA nearEarth Object monitoring programme has identified 1,408 near-Earth Objects that represent potential hazards thanks to their size and trajectory. The Torino scale is used to rate the impact hazard associated with asteroids: a negligibly small chance of collision is rated 0, while a certain impact and impending global disaster is given a 10. To give you some perspective, the most dangerous asteroid is the fearsomely-named VK184, which is coming close to us sometime between 2048 and 2057. It has a gargantuan Torino rating of 1. The Apophis and AG5 asteroids have also whipped up concern in the media, although there is currently little scientific evidence to back up scaremongering (but a lack of scientific evidence hasn’t stopped impacts in the past!) So, while the odds of an apocalyptic asteroid strike causing massive casualties and destruction of our existence are currently infinitesimally small, the potential consequences of such an event would be enormous. So let’s get prepared for catastrophe, just in case…
How to: survive an asteroid impact
The scientific community has developed some interesting tools to investigate what would happen if an asteroid strike actually happened. Top scientists have also come up with some rather unconventional strategies to mitigate for disaster. Imperial College and Purdue University work with a simulation called the Earth Impact Effects Programme to assess the risk of a ‘moderate’ asteroid impact. It offers potentially hours of fun. You can select a projectile, its final destination, its speed, and the angle of impact, and the website will tell you if you will survive, or if you will be squashed by debris, killed by an earthquake, or burned alive. Current scientific strategies listed by NASA to evade the impending doom of an asteroid colliding with Earth include deflecting the asteroid using slow-push-pull ‘gravity tractors’, kinetic impact, nuclear bombardment and other explosives, as shown in the side box . But what would be the consequences of a colossal and un-deflectable asteroid hitting the Earth? The strength of the initial impact would devastate the surrounding environment and uncontrollable wildfires would rapidly spread. The immediate event would be followed by an ‘impact winter’, as enormous clouds of ash and dust enter the atmosphere, blocking out the sun. This loss of sunlight would kill photosynthetic plants and algae that hadn’t already been obliterated by fire or extreme cold. Essentially, any animal larger than an alligator would probably starve. The Committee to Review Near-Earth Object Surveys and Hazard Mitigation strategies recommend a civil defence plan for preparation and recovery that is based upon the standard ‘all-hazards’ protocols for evacuation, shelter, response and recovery for asteroid impact survival. They also consider the implications of possible asteroid events, as shown in the next section. Even if an asteroid is too large to be destroyed or deflected there should still be time to prepare for the impact. Options for the individual survivalist include developing one’s military knowledge and hoarding food within an old nuclear bunker before the impact. Following the impact, one should remain within the bunker for six months, be wary of bandits upon emerging, and ensure a useful supply of guns and ammunition for hunting and bartering within a post-apocalyptic world. So, given all this, perhaps the most useful survival strategy might be to settle in for a night in front of Mad Max to pick up tips...?