2002 NT7 � IT�S SERIOUS THIS TIME KIDS

This Week In Science got scooped on this one � the biggest science story of the week, and we don�t find out about it until right after we broadcast! Such is life. Life, it seems, will get interesting in 2019. There is a giant rock orbiting the sun headed for a possible collision with earth. Of course, we have heard this before. Twice in the past several years, large asteroids have passed very close to the earth, one even coming within the orbit of the moon, and that one was large enough to take out a city had it struck. There was no alarm. But there just may be cause to worry over this one. What makes it so different this time around?
Named 2002 NT7, this asteroid was only found on the 5th of July of this year, just three weeks ago. Since then, the astronomical community has designated it the most threatening object ever found in space. That should be repeated for effect � this asteroid is the most threatening object ever found in space up to this point. Astronomers have even quantified that statement. There is a formula known as the Palermo Scale that is used by Near-Earth-Object specialists to calculate impact risks in orders of magnitude of how concerned we should be� essentially, it is an index for measuring how loudly we should be yelling �holy crap!� 2002 NT7 has been assigned a Palermo Scale rating of 0.06. Doesn�t sound like much at first, but this doesn�t work like the Richter scale. It starts with negative numbers. Anything below negative two is harmless, but anything between �2 and 0 justifies concern. Above zero there is serious cause for concern. 2002 NT7 is the only possible impact event ever to be given a rating above zero. Ever. This is the first time. That is why they are calling it the most serious threat found so far. (For more on the Palermo Scale, click here.) It is not known exactly how big it is, but judging from what we can tell 2002 NT7 is possibly 2 miles long. We do know that it is anywhere from 2 �4 kilometers in length, most likely very unevenly shaped. When it was initially found by the LINEAR Observatory in New Mexico, a hasty preliminary orbit was charted for the asteroid. This suggested that it was on a course to impact earth on February 1st, 2019. Of course, this was based only on the scanty data available at the time of discovery. In the past weeks, many more telescopes across the globe have been turned on the asteroid and it is hoped that its orbit, and the likelihood of collision, will be reckoned much more precisely within the next few months. Additionally, we�ll be able to view it another 18 months before it disappears behind the sun, and it�s 2.2 year orbit will bring it near again several times before the projected date of possible impact. Astronomers have been quick to point out that they hope, some even say expect, that further observations will confirm that it will be a near miss rather than a direct hit.
So, how concerned should we be? And what exactly does a �near miss� mean, anyway? A near miss will be very near indeed. One way or another, we will be guaranteed one hell of a show 16 and a half years from now when 2002 NT7 approaches. Even if it turns out to be another Y2K non-catastrophe, it will be neat to watch. The asteroid is so big that we would probably be able to see it even if it passes a million miles away, about five times the distance of the moon, due to the sunlight that will glint off its pocked, rotating surface. Highly unlikely as it is, wouldn�t it be cool to see it skip off the upper levels of our atmosphere? That would be a spectacular light show. Loud, too. And even if astronomers guarantee that it will not hit, there are sure to be those who run to the hills nonetheless. Should be a fun party.
In the here and now, though, what are we left with? We have almost 17 years to take action, which is on the positive side. But what do we need to know before we take action? In other words, suppose that we can only say with 95% certainty that the asteroid will miss the earth� what then? Is a one in twenty chance too great to avoid taking action? Personally, I would feel that it is. But what about a one in a hundred chance� what about one in a thousand? The first thing we need to know is its precise course; after that, it would make sense to determine from what it is made. It could be a big rock pile, essentially a malicious dirtclod in space. On the other hand, it could also be a huge chunk of solid iron-nickel, in which case we�d be in even deeper trouble. Aside from a rubble pile being (arguably) easier to deflect than a more solid asteroid, imagine the difference between getting hit on the head with a dirtclod instead of by an anvil dropped from ten stories up� the dirtclod will only maim you horribly and might kill you, but unless you are Wile E. Coyote the anvil will kill you dead.
Let us consider what would happen if an object such as 2002 NT7 were to strike our planet. From what we know, it would hit that February day/night (depending where on earth one is) with an initial impact velocity of fifteen miles per second. The long-term effects would be fairly different, depending on whether or not it decides to strike land or sea, but the immediate effects would be dramatic no matter where it impacts. Hitting land, the asteroid would instantly bore a hole a kilometer or two into the ground, vaporizing the planet�s crust at the impact site. This would immediately convert the rock, both the planet�s and the asteroid�s, into super-hot gasses that would extend high into the atmosphere before slowly settling around the planet. Hot, thousand-mile-per-hour winds would rush out in all directions with a force far greater than the pressure waves created by any hurricane or nuclear weapon. The gales would topple trees and skyscrapers instantly, like Mike Tyson going up against Gary Coleman. The winds would also set the entire surface on fire for a thousand or so miles in all directions. They would destroy everything in their path. The atmosphere in that area would literally burn. The sky would be almost pitch black near the huge crater in the minutes after the collision, but no one would be there to winess it. If on a continent, that continent would be completely devastated. There would be no hope of life for anyone or anything in Europe, North America, or Africa, if it were to strike any of these. Those on other continents, while not dying right away, may wish that they had.
Earthquakes the magnitude of which nobody has ever felt - like 10 to 12 on the Richter Scale, possibly even higher - would begin to spread across the planet, razing buildings that had been spared the ferocious winds by dint of their distance from the impact site. It is possible that these will cause volcanic eruptions, maybe even in places that aren�t widely thought of as being volcanically active. And there will be tidal waves, big ones, even if 2002 NT7 strikes a continental land mass. And if it strikes water? The seawater around the plummeting asteroid will instantly boil off all the way down to the ocean floor in the trajectory of the rock. At the seabed, the impact and crater size will be slightly diminished than if it hits land, as the ocean water would act as a sort of cushion, very moderately slowing down the asteroid and lessening its impact inertia when it hits solid rock at the seabed. Of course, this factor is highly variable depending on how deep that particular patch of ocean is in which the strike occurs. In an ocean scenario, the tidal waves would be huge. We would be talking about truly inconceivably huge, Hollywood wrath of God style really gigantic tidal waves. Waves a mile high. And, to be totally accurate, they wouldn�t be tidal waves at all, as the moon and its tidal influence would have nothing to do with their origin. They would be seismic impact waves and they could possibly reach hundreds of miles inland in low-lying coastal areas. Most of humanity lives, of course, in low-lying coastal areas. These waves would circle the world several times before dying out and would hit all but the most sheltered shorelines. It would be a bad time.
Longer term, a given factor would be massive and global loss of life. Not just human life either, but many plants and animals. Species prior to the impact that had been on the brink of extinction would most certainly perish entirely, and many others that may have seemed just fine would also succumb to extinction. It would be tough going for all the survivors. A fine layer of ash would settle over the entire surface of the planet, more ash if it were from a land impact. Fires on the continent that got hit would burn out of control until there was nothing left to burn. Most surface vegetation would die in the few years following the event, and of that which clings to life, much of it will continue to die in the decades that follow. Civilization around the world would utterly collapse; there would be no way modern production and distribution methods could continue in any capacity remotely resembling the way they operate now. Not to sound preachy, but we are already having a hard time sustaining our current global population without the help of an asteroid impact. 2002 NT7 would instantly cause climate change much more severe than the worst consequences of anything that would be caused only by human industrial pollution. Current global warming trends may, if not altered, raise temperatures an average of two or three degrees (Fahrenheit) over the next two hundred years. This is certainly significant, but it is nothing to the ten to fifteen degree likely drop in temperature to be experienced in the years just after an impact such as this would be. Furthermore, that temperature change would be a global average. Regionally, expect to see changes that vary wildly over current norms. Given the tenacity and ingenuity of humans, coupled with the resources of certain wealthy individuals and governments, there would surely be isolated pockets of people who manage to survive, if only by feeding on pre-stocked (a polite way of saying �hoarded�) preserved foodstuffs. But their world would be entirely changed and nothing resembling modern civilization would jump back on its feet as if nothing had happened.
If 2002 NT7 were to strike our home, it would be the kind of event that happens very rarely, even on astronomical and geologic scales. Things as big as this asteroid, some much bigger, have hit the earth before. They are responsible for shaping life on this planet to a large extent, and we owe much of the atmosphere we currently enjoy to their continued and ongoing bombardment. Unless future action is taken, rocks as big or bigger will hit us quite a few more times in the coming aeons. However, it is still very uncommon for rocks of this size to strike the planet � on the order of a one in 15,000,000 chance any given year. When they do hit, they change things dramatically. They change the composition of the atmosphere, largely at first, but even as the fallout settles, the atmosphere is permanently changed, however slightly. It is life that must adapt in the aftermath. On that point, the geologic and fossil records show that when large extinction events occur, those suspected to be related to a large impactor, it is the physically smaller in size species that tend to adapt and proliferate in the altered world that follows. Remember, a rock not much bigger than 2002 NT7 is thought to have killed the dinosaurs 65 million years ago. It was the very early mammals living as proto-mice at that time who crawled out of their holes, no longer afraid of reptilian predators that needed a warm climate, and became our early ancestors in those dark cold centuries following the impact. We would witness what it is like to be on the receiving end of punctuated equilibrium. And that would suck.
Having said all this, it is admittedly a ghost story. It is a tale of what would happen, but it is not to say that it will. If it was determined that 2002 NT7 does actually pose a grievous potential of hitting the earth, it is difficult to imagine the nations of the world not taking action to prevent it. And it is entirely preventable. We have plenty of time, and we have the resources. The costs would be large, but they would be insignificant to the cost of not taking action. It may need not even cost much more than a crewed mission to Mars. Blowing up the asteroid with nuclear missiles, or trying to break it up somehow from the inside, would be highly costly and ill-advised, not just because of the infeasibility of such schemes but also because they probably would just compound the problem by making many smaller but still quite large rocks about to hit us, rather than just one big rock. Far better would be to nudge the asteroid off course, the earlier the better. This could be done a number of ways; this reporter prefers the solar sail method. And what a great way to jumpstart the space industry and finally get our spaceships up to 21st Century specs. It�s been 33 years since we landed on the moon and it�s time we do something heroic again.
current science news posted by ted at 7/24/2002 09:54:00 PM