Now, according to the NASA Web site for asteroid comet impact hazards, which is carried out by David Morrison is the expert for such things – the NEO or near Earth object census report has classified and catalogued a range of potentially damage and non-threatening asteroids and comets (as of 2009). There are 551 known ATEN or objects, crossing 3355 Apollo, or Earth orbit orbiting Mars crossing objects.
From the point of view of risk management, it is safe to say that we in fact need a planetary defense system we were wiped out by asteroids and comets here on Earth, after which reigned all dinosaurs protection for 400 million years from this. From the perspective of scientific astronomy or by using the probability one could think mathematics that worth just not against to defend such a rare event. What, they take a risk of human extinction, and remember, this is those who can buy insurance, and pay off when it is happens tomorrow, it would be someone not the thing, or does not collect the claim in any case.
We should not also with Mars crossing asteroid terribly be affected until we have a manned colony there, but cross the Earth those could and perhaps the most could one day the earth meet in the 1 million years. There were also 2802 Cupid the objects in orbit around the Earth, so are not a threat. TNO for trans-Neptune-objects, and there is a possible Earth 1130 that far from orbit crossing incident, unless, by something else and sent to or near our Earths orbit encountered it us.
Now for the kicker many scientists that we have classified only 10% of such objects, the Earths orbit, cross believe this could be very scary thought is. There were important events that should be taken into account, in the genus risk assessment in the case of an asteroid or comet strikes the Earth. Do you think that the one that killed the dinosaurs 1 million times the explosive force of the Hiroshima nuclear detonation and the Russian Siberian June 1908 Tunguska explosion over 100 times was Hiroshima.
Needless to say, Earth has taken forward has been and is in any case again in the future be taken. Please consider this, the threat is real, and it is really important for the survival of the human race.
1. Power point presentation online; Cosmic impacts and evolution by David Morrison on the NASA Astrobiology Institute – August 2006.
2. Power point presentation online; Impact sterilize Earth by David Morrison of NASA.