A 10 kilometer wide asteroid is heading right for Earth. Science and technology have enabled the human race to pre-date years or decades before, when this rogue space body will pierce our atmosphere and strike Earth with enough force to envelope the planet in dust, resulting in a global winter that will render virtually all life forms extinct including humans. What defense mechanisms do we have in place to deal with a threat like this? At present, absolutely nothing.
If you're like most people, you probably think the aforementioned scenario too unbelievable and horrific to actually happen. Perhaps you've seen the Hollywood movies “Deep Impact” and “Armageddon” and chalk up the whole Asteroid Impact Threat to just so much "Science Fiction".
The sad truth is that there is no fiction involved, only science. Consider some of the scientific facts we already know.
- A 10 km wide asteroid did hit Mexico's Yucatan Peninsula 65 million years ago. The energy of the impact was comparable to 100 million megatons of TNT (The bomb dropped on Japan at Hiroshima was 13 kilotons and killed 70,000 people. (1000 kilotons =1 Megaton). The impact destroyed everything within a radius of between 400 and 500km, triggering global tidal waves, worldwide firestorms, and massive earthquakes. It also left a worldwide layer of extraterrestrial dust. Most scientists now believe that this event is responsible for the extinction of the dinosaurs.
- The largest ever recorded asteroid hit happened in Tungusta, Siberia in 1908. It was only 30-50 meters in diameter but its impact was comparable to a 20 Megaton bomb. It felled an estimated 80 million trees over 2,150 square kilometers, and would have completely destroyed a city the size of New York.
- About 2,000 objects massive enough (1 km diameter) to cause global catastrophe are known to cross Earth's orbit. Such an impacting object would wipe out 25% of humanity.
Frequency of Impactors:
- Pea-size meteoroids - 10 per hour
- Walnut-size - 1 per hour
- Grapefruit-size - 1 every 10 hours
- Basketball-size - 1 per month
- 50-m rock that would destroy an area the size of New Jersey - 1 per 100 years
- 1-km asteroid - 1 per 100,000 years
- 2-km asteroid - 1 per 500,000 years
Feeling a bit less secure? You should be, because many scientists believe a hit from a km or greater size asteroid is long overdue. Put it this way, the asteroid that hit the Yucatan Peninsula 65 million years ago was the last one scientists know of. According to the NEO Impacts division of the NASA Ames Research Center, a NEO with about 1 million megatons energy (roughly 2 km in diameter), on average, should collide with the Earth once or twice per million years, producing a global catastrophe. If you believe these statistics, we are at best 64 million years overdue.
Why are there no defensive mechanisms in place to deflect NEO's from hitting us? It's certainly not a question of lacking the scientific and technical resources and means to build such a device, so why haven't we built one?
The scientific community's conflicted opinions on how to approach the problem of NEO impacts, is at least partially responsible for this lack of action.
Some NASA scientists try to downplay the issue with articles on Risk Analysis and Statistical Probabilities.
In the article Ask an Astrophysicist in the Nasa Goddard Space Flight Center Homepage they state that “Today a motor vehicle accident occurs every second. Auto accidents cause an injury every 14 seconds, and every 13 minutes a car accident results in a fatality. More than 31 million accidents occur per year, at an annual cost of almost $100 billion. Yet most people continue to drive their automobiles regardless. For the same reason, that we can't live our lives paralyzed by the fear that something bad may happen, we shouldn't let the remote possibility of being struck by a meteor or asteroid rule our lives.”
David Morrison, Responsible Nasa Official for the Nasa Ames Research Center, Asteroid and Impact Hazard Branch in his "FAQs About NEO Impacts" article states that a person has about one chance in 40,000 of dying as a result of an asteroid collision.
On the other end of the spectrum, you have people like NASA astronaut and former University of Hawaii Physicist Edward Lu calling for the construction of a 200-300 million dollar space tractor to be built immediately to try and deflect the trajectory of NEO's headed for Earth. Citing just one of the big top ten NEO's currently being tracked, the asteroid Aphopis, Lu points out that it will come so close to Earth in 2029 that Earth's own gravity might change it's orbit enough that it hit's us when it comes back around again in 2036. Nasa has estimated that an impact from Apophis, would release more than 100,000 times the energy released in the nuclear blast over Hiroshima.
In light of the unusual destructive weather we've been having recently I'll leave you to chew on what I think are the most disturbing statistics I've seen on the probability of Death from an Asteroid because I tend to take facts seriously when they come from the United States Department of Defense. Are you seriously willing to gamble on a threat that is more likely to kill you than a tornado or a flood? Think about it.
