Asteroid Deflection

[JohnHunt]

I would like to make the case that the threat to mankind from asteroids is quickly diminishing and that the case for doing something NOW about the threat is also rapidly decreasing.

First, significant asteroid threats are pretty rare. Statistically, we'll probably have nothing more than a Tunguska-level event by the time that we discover (say in 100-150 years) the location and direction of all asteroids presenting a significant threat. Yes, during that time we'll discover asteroids which have our name written on them. But, statistically, they will be so far out in time that it will give us plenty of opportunity to master deflection missions.

Furthermore, the greater threats come from larger asteroids. But these asteroids can be detected at a greater distance. Even if we don't have time to mount a deflection mission, we would have time to mount an evacuation of target or tsunami areas. So the threat to human life becomes smaller and smaller as we are able to detect and avoid (through evacuation) smaller asteroids.

We have already detected probably greater than 90% of the >= 1 km sized civilization-killing asteroids. In 2008 a meteorite only 2-6 meters across was detected with 20 hours notice. It detonated with about 1/15th of the equivalent of the Hiroshima bomb. 20 hours notice is far more than enough time to walk the two km or so to safety (i.e. 6/100th of a mile per hour).

My point is that detection should be our first priority and that the threat is not so great as to warrant diverting funding from greater priorities.

[joertexas]

I would like to make the case that the threat to mankind from asteroids is quickly diminishing and that the case for doing something NOW about the threat is also rapidly decreasing.

First, significant asteroid threats are pretty rare. Statistically, we'll probably have nothing more than a Tunguska-level event by the time that we discover (say in 100-150 years) the location and direction of all asteroids presenting a significant threat. Yes, during that time we'll discover asteroids which have our name written on them. But, statistically, they will be so far out in time that it will give us plenty of opportunity to master deflection missions.

Furthermore, the greater threats come from larger asteroids. But these asteroids can be detected at a greater distance. Even if we don't have time to mount a deflection mission, we would have time to mount an evacuation of target or tsunami areas. So the threat to human life becomes smaller and smaller as we are able to detect and avoid (through evacuation) smaller asteroids.

We have already detected probably greater than 90% of the >= 1 km sized civilization-killing asteroids. In 2008 a meteorite only 2-6 meters across was detected with 20 hours notice. It detonated with about 1/15th of the equivalent of the Hiroshima bomb. 20 hours notice is far more than enough time to walk the two km or so to safety (i.e. 6/100th of a mile per hour).

My point is that detection should be our first priority and that the threat is not so great as to warrant diverting funding from greater priorities.


There is a concept in the aviation world called the Big Sky theory. This states that there shouldn't be too many midair collisions because the sky is big and airplanes are small. That theory works well -right up to the point where you get hit.

Now, I do agree that the chances of being hit by an asteroid are very small. However, it only takes one hit to change our world forever.

JR

[JohnHunt]

However, it only takes one hit to change our world forever.

OK. But we can't spend our lives taking expensive precautions against those things which are highly unlikely to happen even if the consequences are big. We have to prioritize. If I step out of my home, theoretically I could get struck in the head by a pea-sized meteorite. But that doesn't mean that I'm going to live underground for the rest of my life.

From my analysis before, the risks, although large, will be knowable and avoidable (by evacuation) in the near future with at least a day's notice for the really big threats. IF we find out that a sizeable astroid is coming which will do considerable damage in five or more years, then yes, we should spend the large amounts of money to deflect it. But shy of this, the utility of spending so much money on an unlikely risk is unjustified. Yes?

[joertexas]

OK. But we can't spend our lives taking expensive precautions against those things which are highly unlikely to happen even if the consequences are big. We have to prioritize. If I step out of my home, theoretically I could get struck in the head by a pea-sized meteorite. But that doesn't mean that I'm going to live underground for the rest of my life.

From my analysis before, the risks, although large, will be knowable and avoidable (by evacuation) in the near future with at least a day's notice for the really big threats. IF we find out that a sizeable astroid is coming which will do considerable damage in five or more years, then yes, we should spend the large amounts of money to deflect it. But shy of this, the utility of spending so much money on an unlikely risk is unjustified. Yes?

Yes. We have to search for new asteroids to mine anyway, and that equipment can detect anything significant on a collision course, too. Once we get established, a close asteroid will mean we don't have to run out and get it - we can steer it into a more convenient orbit.

JR