Without reading the article, what I imagined was a mad billionaire trying to eradicate life on earth by 2025.
Yes, I realize 500 tons is far too small to do that.
Yes, I realize 500 tons is far too small to do that.
I expect some sort of space treaty to regulate the safe operation of such a venture, and in return provide some liability limits on the required insurance. Otherwise the investors have a tiny chance of being wiped out financially if some city gets hit.
I agree with you. I expect that should a city get hit, then international outcry would lead to the confiscation of all of the investor's assets, despite being shielded by a limited liability corporation.
For that reason the investors need insurance - and a very large amount of it considering the damage that a direct hit on a major city might cause. The investors would seek some sort of limit on the liability - say 100 billion dollars, and in return they should eagerly submit to regulatory oversight of their plans, procedures and operations.
In order to insure such an asteroid moving scheme and establish a premium, insurance companies must determine a risk probability distribution, and they must know what the maximum liability would possibly be. Over many decades, there may be observations of close calls or actual damage causing situations that can inform the actuarial calculation, but at the initial point its simply educated estimates.
So the investors chose that asteroid diameter so as to minimize potential damage due to an impact on Earth.
This is true for everything moving in space: vehicles, rocks - all potential weapons .. just from (ahem) potential.
We need to be real careful that we don't regulate this activity right out of existence.
Carl Sagan spoke out against research into destroying "rogue" comets or asteroids that might hit Earth. He believed that the potential for military misuse of the technology far outweighed any real collision threat.
... shouldn't they be?!
According to this calculator, a 500ton roughly spherical rock, assuming a density of 3g/m^3 so a surface area of 3600m^2 would live for 20 years at 500km altitude.
http://www.lizard-tail.com/isana/lab/orbital_decay/
At altitudes higher than 1000km, the thing could live for centuries, although no matter how high, orbits still get perturbed eventually and decay (in the Earth-Moon system).
(Note that at 380km altitude, the ISS is never more than 1-2 years away from burning up in the atmosphere, so it needs periodic boosts to prevent it)