Asteroid Itokawa was visited by the Japanese Hayabusa probe in 2005. Last year, the probe delivered samples of dust back to Earth for some much-needed analysis. Click to enlarge this image.
JAXA
Social networking has never before made me feel quite so vulnerable to space rocks!
A few days ago on Feb. 9th, I received a tweet advising me that asteroid 2011 CA7 had just shot between the Earth and moon at a distance of only 0.3 lunar distances -- or 115,300km! That was close, but the car-sized asteroid flew harmlessly by and it was time to breathe easy.
Most of humanity was blissfully unaware of this close encounter but as someone who was in the know, I found myself wondering if it's better to know about these events or to remain in contented ignorance of pending destruction and near misses.
SLIDE SHOW: Asteroids and Near-Earth Objects
Interestingly, there are 822 known near-Earth asteroids with a diameter of 1 kilometer or more that -- compared to tiny, 3 meter-long 2011 CA7, that would have most likely burned up in the atmosphere anyway (assuming it wasn't a chunk of iron!) -- are of more cause for concern. If one of those monster space rocks was on a collision course with Earth, then our days may well be numbered and the Doomsday Clock well and truly ticking.
Of all those 822 lumps of Armageddon, there are only 2 (one of them being Apophis) that have an even remote chance of coming "too close" to the Earth before 2112 and, as a result, have been given a "Torino rating" of 1.
The Torino scale rates asteroid impact hazards from 0 (equivalent to "no significant consequence") all the way up to 10 (which basically means "we've had it"). So, as you can see, a rating of "1" is of little cause for concern and future observations may very likely drop the risk level down to zero.
The problem with discovering asteroids and knowing whether they are a threat is that it takes time and lots of observations to understand their trajectory and nature.
It's like taking a photograph of a moving tennis ball. Use a fast shutter speed (equivalent to just one observation) and you get a nice, sharp image so can pinpoint its exact position. Unfortunately, you won't have a clue about the direction it's heading. If you use a slow shutter speed (equivalent to lots of observations) then you get a very blurred picture, but you can now deduce its speed and its direction.
ANALYSIS: Wayward Asteroid Gets Bent
Thankfully there are a number of automated projects out there looking for possible cosmic bullets with Earth's name on, such as the Jet Propulsion Laboratory Sentry System. The question is if JPL or another organization spotted something heading our way, what could we actually do about it?
Of course, the first thing to do would be to call Bruce Willis as he has the monopoly on saving the world! In reality, it is left to scientists to come up with real options.
The best news of all is that we have plenty of options, but the chances of success are very dependent on the size of the object, orbit, speed, composition and how early we spot it. Early warnings are crucial in this game.
There are, thankfully, many theories and plans on how we can deal with such threats but in the grand scheme of things, they are primitive. It will take a few more years before a really robust solution is available but for now, we may have to just sit tight, wait and keep our fingers crossed.
So should we even try looking if there's not a lot we can do about it? I think the answer is a very big "yes!" It's amazing how a pending disaster can focus our minds, and it might be just what we need to develop that all important "Bruce Willis style" plan to save the world.
Tags: Asteroids, Disasters and Accidents, Impact Craters, Meteorites
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