Low-Probability, High-ImpactThere's a wise old saying about "not putting all your eggs in the same basket". This is an argument for the eventual colonization of space. But for now, there's another saying that applies: "If you put all your eggs in the same basket, watch the basket." This means a few things... First, we should protect the ecosystems on which we and all of life on Earth depend. But it also mean that we should watch out for external threats such as asteroids; it would be extremely sad if we finally made our civilization sustainable only to be hit by the Big One.
I'm not trying to be alarmist. Big asteroids hit the Earth very rarely, and there are other problems that have a much higher probability and should get priority. But when scientists say that something "happens once every X millions of years", it doesn't mean that we're safe for X millions of years, it means that every year on average there's about a 1 in X chance of it happening. It's very low, but sometimes people win the lottery.
If for a relatively small sum of money we could better monitor near earth objects ("The ISO Deep Asteroid Search indicates that there are between 1.1 million and 1.9 million 'space rocks' larger than 1 kilometre in diameter in the so-called 'main asteroid belt'") and calculate their trajectories using supercomputers, we'd be a bit safer and would have more time to react if something is headed our way. We'd be watching the basket.
For more on this topic, check out some articles I wrote about NEOs:
If you're curious about what kind of impact an asteroid hitting the Earth would have, you can simulate all kinds of collisions with the Impact: Earth! simulator created by Purdue University and Imperial College in London. It allows you to input the object's size, density, angle of attack, how far you would be form the blast, would it be on land or in the ocean (tsunami!), etc.
This tool has recently been updated to take into account more factors and give more realistic results (which are all the more scary).
Don't lose too much sleep over asteroids... But remember that we have the technology to monitor them, and should use it. NASA is already doing some good work in that area, but we could do more. It's something that greens should support.
Via Purdue, BBC
More on Space & the Environment
Japan's Moonshot? $21 Billion Invested in Space-Based Solar Power
Shocking Space Debris Images
Ain't Technology Amazing? Scientists Can Track Penguin Poop From Space!
Space-Age Tech Coming to a Building Near You: Aerogel as Insulation