Oddly, everyone seems relieved that asteroid 2011 MD sailed harmlessly by; I, on the other hand, wish it had hit us. Yes, really.
On Monday, at approximately 1 p.m., 2011 MD buzzed our planet. As cosmic distances go, this space rock narrowly missed the bulls eye — in fact, it hit the bull; slingshotting off the “rim” of our planet’s gravitational well.
The orbit of the 5-20 meter-wide asteroid was greatly affected, almost completing a “U-turn” as it passed over the Northern Hemisphere, made close approach over the Southern Hemisphere (at a distance of around 7,400 miles) and then exited the Earth system over the Northern Hemisphere again.
Although this “near miss” was close, it wasn’t the closest. According to astronomers at Remanzacco Observatory in Italy, a 2-3 meter-wide asteroid (called 2011 CQ1) came within 5,480 kilometers of Earth on Feb. 4. 2011 CQ1 is the “closest near miss” on record.
But probably the most famous “quasi-near miss” was The Great Daylight Fireball of 1972 when a 3 meter-wide meteoroid entered our upper atmosphere for a few seconds and left again after passing over the USA. Technically the 1972 fireball hit our atmosphere, so 2011 CQ1 still holds the “near miss” record.
Earth gets hit by tons of incoming space rock each year. The vast majority of space debris that hits our atmosphere, sparking as transient meteors, comes in the form of interplanetary dust and particles no bigger than a grain of sand (37,000-78,000 tons of the stuff is estimated to hit us every year) — analogous to bugs smacking into a truck’s fender on the freeway.
But occasionally, 5-to-10 times per year, the Earth hits the cosmic equivalent of a small stone, chipping our truck’s windshield.
For example, on Oct. 7, 2008, a small, 3 meter-wide meteoroid called “2008 TC3″ hit our atmosphere 19 hours after it was spotted by the NASA-funded Catalina Sky Survey for near-Earth objects. This observation was unique in that it was the first time astronomers had spotted a small asteroid before hitting the Earth’s atmosphere, correctly predicting the time and location of impact (over the Nubian Desert in Sudan).
The impact was carefully observed, and video evidence of the fireball was captured on camera (a snapshot of that video is pictured below). An infrasound array in Kenya also detected an explosion in the atmosphere, with an energy equivalent of 1.1–2.1 kT of TNT, confirming the impact. Excitingly, 600 small fragments of the meteoroid were also recovered from the desert.
The smoky remnants of the 2008 TC3 impact of 2008 TC3 over Sudanese skies (NASA)
This was a very impressive achievement for asteroid hunters; detecting a small meteoroid and predicting its location of impact was a world first, a testament to the astronomers working on asteroid surveys all over the world.
Last Wednesday, the 5-20 meter-wide 2011 MD was spotted, but this time with over five days notice — once again, a fantastic achievement considering the asteroid’s size
There seems to be much relief that 2011 MD missed us, but truth be told, this asteroid would have hit the atmosphere and exploded much like 2008 TC3 did. Although the air burst would have likely been more energetic (as it was larger than 2008 TC3), 2011 MD certainly wouldn’t have caused any major damage to the ground, least of all to populated areas.
Depending on its composition, 2011 MD would have disintegrated, with the potential for small meteorite debris to scatter across the South Atlantic Ocean.
If 2011 MD was on a collision course, I have little doubt that a warning would have been issued for air and sea traffic, with the potential for redirected or delayed flights in the South America/South Atlantic region, depending on the predicted location of atmospheric entry.
Undoubtedly there would be mild panic — what if astronomers underestimated it’s size?! — and a huge amount of media coverage.
With a few days of notice, scientists would be jetting down to the southernmost tip of the Americas in the hope of observing this historic impact. Although spotting the impact during the day would be a difficult task, depending on atmospheric conditions, a “boom” might be heard and infrasound arrays would measure the energy of the impact on the atmosphere.
Apart from the obvious scientific advantages of observing a meteoroid slam into the Earth’s atmosphere, 2011 MD would have acted as a warning shot; a planetary flesh-wound of sorts. We live in a cosmic shooting gallery, it’s only a matter of time before something bigger has us in its cross hairs.
Of course, this is all conjecture. 2011 MD flew past, probably to never be seen again. It missed Earth. But for the future of asteroid detection, I think that’s a shame.
The problem with mankind is that we procrastinate.
The reason why we invest very little money in near-Earth object surveys is that the risk perception is very low. After all, how many asteroids have really caused problems in recent years?
There was that nasty dino-killing space rock, 65 million years ago. Oh yes, and that Tunguska thing in 1908. Something obviously hit Arizona 50,000 years ago, too.
But why worry? All these cosmic collisions happened in the distant past, we don’t need to be worried now, do we?
The inner solar system may seem nice and peaceful, but much larger space rocks than 2011 MD are floating around and many are extinction-level events.
Fortunately, astronomers are confident that they’ve spotted most of the large, kilometer-wide “potentially hazardous asteroids,” but a lot more work needs to be done to survey the skies for the smaller rocks that may not wipe out a civilization, say, but could cause upset for a densely populated city. It’s only a matter of time before our planet gets hit.
What’s more, if we had more telescopes looking for asteroids of all shapes and sizes, we might be able to spot the ones heading for us well ahead of time for us to do something about them. But to deflect (or nuke) an asteroid we’ll need an in-space infrastructure. All this takes money, and unfortunately, money is what we’re lacking.
As Phil Plait put so succinctly in the Discovery Channel’s “Bad Universe”:
Perhaps getting hit by a small asteroid — like the fairly harmless 2011 MD — would have shocked the world enough to ask the question: What are we doing about the threat of getting hit by something bigger? Could it have provided political pressure to direct more funds into near-Earth object search programs?
Alas, 2011 MD lives to fight another day, asteroid detection remains underfunded and asteroid deflection remains a distant hope.
Image credit (top): Corbis (edit by Ian O’Neill)