There's a pretty key difference. Deploying countermeasures against an extinction...

		Cushman on March 21, 2012 \| parent \| context \| favorite \| on: IAmA NASA Astronaut who recently returned to Earth... There's a pretty key difference. Deploying countermeasures against an extinction-level asteroid strike is a realistic possibility with current technology. An extraterrestrial human presence which could survive an extinction event just... isn't. Sad as it is to say.