by Spider » Mon Aug 24, 2015 8:46 pm
Deep Earth would purely be a survival option.
Expansion into the inner planets and the belt, otoh, could be a tremendous economic driver. The only reason we do things is because of profit motive (well...or nationalism/dick measuring). There is profit motive in expansion. Just expense with deep survival arks.
The big reason for urgency from my point of view is the degradation of the West, economically. As we start getting dragged under by the costs of supporting ailing populations into extended old age, and as wealth and earnings are eroded by third world competition, we just have less and less capability to front these tremendous spaceflight costs while keeping opposing political pressures under control. Every cent spent on spacecraft is a cent not spent on benefits, after all. As the world's wealth gets spread around more...the piles of it (coupled to technological capabilities) amount to too little to get the job done from any one point. We find ourselves forced into international cooperatives...which are extremely inefficient and self-undermining. (Russia was muttering about finding ways to undock their portion of the ISS a bit back. Insanely enough.)
As for likelihood...the randomness of it is what makes it so scary. There's nothing to be done to reduce the risk, nothing to be done (at present) to deflect an incoming impactor of any meaningful mass. Every day we don't get crunched is a blessing, I guess.
Acceptable risk is calculated as a function of potential loss. When the entire human race is on the line, I don't view any level of risk as acceptable. We could be totally unique. Everything we've done is f**k amazing if you think about it...it has real, axiomatic value. To needlessly risk it...madness.