Good read from Rusty Schweickart
"Former astronaut Rusty Schweickart has already earned his place in the history books by going to the moon with the Apollo 9 mission. However, should an asteroid crash into the Earth anytime soon, killing millions and causing catastrophic damage, he'll also be remembered as the guy whose warnings we ignored."
http://www.wired.com/science/space/news/2007/08/schweickart_qa