The Cost of Asteroid Avoidance

The value of a space program, like the value of anything, is determined by the desires it fulfills or thwarts.

The meteor impact in Russia injured approximately 1500 people and caused tens of millions of dollars worth of damage. The asteroid that narrowly missed the Earth on the same day was three times the length - potentially 27 times the mass - of the Russian meteor.

The asteroid that missed us was approximately the same size as the one that created Meteor Crater in Arizona. However, the composition of the meteor is also important. Meteor Crater was created by an iron-nickle asteroid likely to survive its trip through the atmosphere in one piece. The meteor that hit Russia was a stoney meteor likely to burst in the air.

Of course, the composition of the meteor is also important. The meteor that created Meteor Crater in Arizona was the same size as the asteroid that narrowly missed on Friday, but was a nickel-iron meteor that tends to survive the atmosphere and hit as a solid chunk. The Tunguska Comet that hit in 1908 and destroyed over 2000 square miles of forest. It could ave destroyed 2000 square miles of buildings.

Unfortunately, as an argument for or against a course of action, these types of facts can be deceptive. Humans do a poor job at risk assessment. They tend to read numbers like this, measure the emotion generated by the numbers, and use that as their guide about what to do. This method is not only highly fallible - it is easy manipulated.

Those who have a stake in motivating others to act on the threat have a stake in presenting these facts in a context of, "OH MY GOD WE ARE ALL GOING TO DIE!" while those who do not want money devoted to addressing the threat will focus on the low odds and, "You are more likely to be hit by lightning - or shot" (ignoring the fact that it is far less likely that a lightning strike or a gunman can wipe out the human race).

These types of decisions are not wisely trusted to the gut instincts of people reacting to a hyped up news event. It is a decision best made by a calculated decision of the risks and costs.

An example of the type of decision model I am talking about rational decision model for mitigating an asteroid impact can be found http://www.nss.org/resources/library/planetarydefense/2003-DecisionModelForPotentialAsteroidImpacts.pdf

This paper reports that the potential harm of all known threats are so unlikely that they justify no more than $10,000 in response. However, it does not address the question of the value of discovering a threat we do not yet know about - one that would justify a response in the range that exceeds hundreds of millions of dollars.

There is a nearly 100% chance that we will someday discover a potential impact worth a response in the range of hundreds of trillions of dollars (over several years). We have had several such impacts in the past, and it is almost certain that we will experience similar impacts in the future.

That is to say, if we were to map all of the asteroids and plot their moves well into the future, we will identify the next big impact worthy of a multi-billion (multi-trillion) dollar response. It is out there, waiting to be found. One of those big rocks out there will hit us someday. We just do not know which ones, or when. While many people probably think about this problem in terms of "Whether we will be hit," and answer, "Probably not," professionals in the field are asking, "Which one will hit us next, and when?"

It will be interesting when they announce, "The next big impact will be Asteroid A in on (date)"

Yet, even here there is an issue of applying a discount rate - representing the lower present value of things in the future. If we assume a 5% discount rate - a number I pulled out of the air but which illustrates the concern - a $100 trillion expense 500 years from now only has a present value of less than $800 dollars. There are moral issues concerned with discounting future interests; however, another interpretation of the discount rate is that we simply do not know what resources or interests a future generation will have (or even whether the future generation will even exist).

We may want to include in this the uncertainty over whether people in 500 years will have a space program. However, we are involved in assessing the value of having a space program. There would be a problem with arguing that "we should not invest money in a space program because we assume that future generations have a large and effective space program."

This post illustrates some of the types of concerns associated with determining the value of a space program. As in many things involving risk, gut feeling is not to be trusted. We spend huge amounts of money - and even spend lives - avoiding a very small chance of being killed by terrorists, while devoting significantly less money to avoid the much larger chance of being killed by the next pandemic or asteroid.

It is enough to say that those who think that investment in space development is a waste of time, and those who think it is clearly worthwhile, are - in many cases - both irresponsibly jumping to unjustified conclusions. It will take a fair amount of effort to determine the answers to these questions. It is not the type of issue where simple moral intuition is going to be a useful guide.