Isn't there an economic technique for deciding this question. Multiply the probability of the event by the expected losses then subtract the cost of prevention. If the number is positive the likely losses outweigh the cost. In the event of our extinction all the wealth generating capacities of humans would be lost. And consequently even the expenditure of hundreds billions could make economic sense. Given that the probability of a Deep Impact is as high as 1/100000 in two hundred years. I had assumed that the odds where much much greater.

Should not worry about some object hitting this planet,Humans have already got they own self destruct systems The system is called |Humans.joseph walker.

The Valery Menshikov’s IGMASS proposal is precisely of the type that should be seriously considered. Should we follow the recent example of the oil industry and Obama Administration who assured us that the possibility of something like the Gulf oil spill was quite remote? Was the Tunguska 1908 event rare? In taking down the manned space program Obama is also removing the primary means of planetary defense against Tunguska type events—i.e. large booster launch capabilities. Instead we should immediately launch programs like the deployment of miniature dispersed phased array infrared telescopes to Kuiper Belt utilizing the immediately available Orion-type method of propulsion to achieve relativistic velocities as has been studied at Lawrence Livermore Laboratory.