Now here’s an interesting question. What would happen if a small asteroid like 2008 TC3, the three-meter object that exploded in the atmosphere late Monday, were headed for a large city? We were able to judge with a high degree of confidence that 2008 TC3 would pose no threat to the surface, and indeed, early reports suggest that its energies — 1.1 to 2.1 kilotons of TNT — were expended in the atmosphere. But even the most confident scientists might be hard put to sell the case for calm if the public started imagining worse case outcomes.
David Morrison (NASA Ames) has written about the public response to a small impact scenario, a fact I’m drawing from the recent update of NEO News sent to me by Larry Klaes. Also available is a report from spaceweather.com of a visual sighting of the event, sent along by Jacob Kuiper, general aviation meteorologist at the National Weather Service in the Netherlands::
“Half an hour before the predicted impact of asteroid 2008 TC3, I informed an official of Air-France-KLM at Amsterdam airport about the possibility that crews of their airliners in the vicinity of impact would have a chance to see a fireball. And it was a success! I have received confirmation that a KLM airliner, roughly 750 nautical miles southwest of the predicted atmospheric impact position, has observed a short flash just before the expected impact time 0246 UTC. Because of the distance it was not a very large phenomenon, but still a confirmation that some bright meteor has been seen in the predicted direction.”
The best case scenario I can imagine for getting us to develop the tools needed for asteroid deflection is having the occasional small event like this making news around the globe. And indeed, we should have no shortage of events to point to, according to Don Yeomans, who toils at the Near-Earth Object Office at the Jet Propulsion Laboratory:
“We estimate objects this size enter Earth’s atmosphere once every few months. The unique aspect of this event is that it is the first time we have observed an impacting object during its final approach.”
Even so, we had little lead time, with the object being discovered only a day before its encounter with Earth. And if we found a much larger object on an equivalent course? We know that Tunguska-class events may occur as frequently as every 100 years, a grim reminder that space debris is wildly variable in size and can create catastrophe where it falls. Let’s hope it doesn’t take another Tunguska to awaken the public to the need for robust space-faring technologies that can nudge incoming asteroids into safer trajectories.
Emily Lakdawalla did an outstanding job on this story for the Planetary Society weblog. Let me quote from her thoughts on public reaction to a larger object:
But of course we now have to ask ourselves: what would have happened if the object was much bigger than 2 meters in diameter? Reassuringly, the first thing that would have happened is that the detection most likely would have happened much earlier. The bigger and more hazardous an object is, the brighter it is, and the sooner we will detect it. We will likely have way more than 20 hours’ warning of an incoming dangerous object. Still, though, the warning time for a tens-of-meter-diameter object could only be measured in days. If we’d had three days’ warning of a dangerous impactor heading for Sudan, what could the world have done? The remote location of the impact would have been fortunate for humanity in general, but disastrous for the few people who lived out in that remoteness. Could the developed world have done anything to prevent yet another humanitarian disaster from befalling the Sudanese?
These are highly theoretical questions at the moment, but they could become far more pointed at any time. All the more reason to be thinking, as the Association of Space Explorers continues to do, about the possibilities of crafting an international response. That one is dependent upon politics more than technology, and an equally tough challenge. For more on the public response to small impacts, see Morrison, D. “The Impact Hazard: Advanced NEO Surveys and Societal responses,” In Comet/Asteroid Impacts and Human Society (P. Bobrowsky & H. Rickman, eds.) Springer, New York (2007).
It’s an uncomfortable fact of life that big disasters do, and will continue to happen. There are at least four types of natural disaster that can befall a city with little or no warning–volcanoes, earthquakes, tsunamis, and asteroid impacts.
While we will likely get several days or even weeks warning of a devastating volcanic eruption (but not necessarily), earthquakes are likely to strike without warning, and with tsunamis, you might get a couple of hours if you’re lucky.
So the reaction to an announcement that an asteroid is heading toward a large city would not really all that different from the reaction to hearing that your city is about to be leveled by an earthquake or submerged by a tsunami or volcanic eruption.
If there was no warning, then all you can do is rely on the emergency service to help clean up the mess left behind. With just a couple of hour’s warning, it’s every man for himself. More than that you begin to get the emergency services involved in an organized evacuation. Cities whose location requires them to have an existing evacuation plan (for hurricanes or volcanoes) will probably handle the situation much better, but since 9/11, I believe all large cities have enhanced their capabilities in case of a major terrorist strike.
Probably the one distinguishing factor of an asteroid strike would be the difficulty in pinpointing the likely epicenter of the impact. But in some ways, it’s still not all that different from a hurricane evacuation except in the size of the uncertainty. You don’t want until you know exactly where disaster will strike, you make your best informed decision at a time that gives you the best chance to get everyone out of the way.
So, it’s an interesting question, but it’s really not an unfamiliar one if you consider the dangers many cities around the world already face. Having enough warning is still the most crucial factor. Otherwise there is little anyone can do to get out of the way.
tacitus raises some valid points. However I would point to a different disaster scenario as being more like an asteroid of the sort Lakdawalla describes. This would be a hurricane.
– Several days notice.
– Some but not perfect predictability of path, force and scope of disaster, though improving as impact approaches.
– Many turn into duds, and it’s hard to know which ones.
Expect lots of resistance to evacuation of likely impact areas. Those that do evacuate tend to do so too late, resulting in evacuation ‘disasters’. There are lots of similarities.
Also, the more notice people have the more time there is for crazies to whip up panic. Then look at 2008 TC3. I had to dig to find any mention of it in mainstream media. Almost no one knows about it, since, according to the old cliche, if it doesn’t bleed it doesn’t lead. Find it a week earlier and I bet it gets front page and TV news lead, accompanied by journalistic waffling and distortion that cause widespread concern even if unwarranted.
The problems outlined above are being taken care of (partially at least) this very moment: A JPL scientist just told me that they are working on a computer system that will, in similar cases, display the current impact zone and probability ellipses in real time, for all the world to see (such a software was running in their lab as events unfolded on Oct. 6/7). It would then be up to “the authorities” to use this information for decisions – and this, of course, is the tricky part …
I wonder whether or not distributed computing could be put to use to search out objects in space. Sort of like a SETI@Home for NEO objects. I realise that one of the requirements for this to work is a huge amount of data that can’t be analysed and so causes a backlog under normal circumstances. Which is probably not the case at the moment. However, let’s entertain the thought that somehow scientists managed to picture large amounts of sky at various resolutions in order to gather extreme amounts of photographs. Couldn’t distributed computing be put to use to analyse the photographs at the various resolutions and flag ‘interesting’ objects. Telescopes would then track these objects for long enough to be able to establish trajectories. This could all be done automatically with some objects being referred to scientists for more examination.
The system could function like an automated tracking system, taking say 20% of the online time for each telescope around the world every week to photograph the skies and build a database of objects and their trajectories. Using distributed computing would no doubt make this process extremely fast, and all objects could be re-photographed every now and then to re-calculate their trajectories in case of some astronomical event changing it’s path somehow.
I’m not sure if this sort of thing is feasible, so feel free to shoot it down ;)
Shaun, I’m a great believer in distributed computing, and you’re certainly right that we should be gaining a lot more data in coming years as the hunt for NEOs intensifies. Whether and how to implement a distributed computing application is beyond my skills, but maybe some of the readers here have more ideas. Fascinating notion!
Orbit@home (http://orbit.psi.edu/?q=node/10) is such a project which is working on providing better search methods for finding NEA’s as well as monitorring them.
Iowa State Research Center Sponsors Asteroid Deflection Symposium
Ames IA (SPX) Oct 21, 2008 – The Iowa State University Asteroid Deflection Research Center (ADRC) is sponsoring an Asteroid Deflection Research Symposium on October 23-24, 2008, at Doubletree Hotel Crystal City-National Airport, Arlington, Virginia.
The purpose of this symposium is to exchange technical information and to develop an integrated multidisciplinary R and D program for asteroid deflection/fragmentation … more
http://www.spacedaily.com/reports/Iowa_State_Research_Center_Sponsors_Asteroid_Deflection_Symposium_999.html
http://www.newscientist.com/blogs/shortsharpscience/2008/10/trio-of-asteroids-buzz-earth.html
October 23, 2008 10:01 PM
Trio of asteroids buzz Earth
We’ve been missing asteroids that have barely been missing us. All of us, that is, except a small band of asteroid hunters who’ve lately spotted some surprisingly tiny space rocks that have come closer to Earth than any found before.
On 6 October, they spotted an asteroid a few metres in diameter called 2008 TC3 just hours before it plunged into the atmosphere over Sudan.
Three days later, they spotted a metre-size space rock designated 2008 TS26 a few hours after it missed the Earth by 7000 kilometres. And on Tuesday, they spotted a slightly larger object called 2008 US that just hours earlier passed some 25,000 km above the surface.
Those are three of the four recorded objects that have come closest to Earth, according to a tabulation by the Minor Planet Center at the Harvard-Smithsonian Center for Astrophysics. The fourth, 2004 FU162, missed the Earth by a mere 6500 kilometers in 2004.
This month’s sudden rash of discoveries doesn’t mean something up there has started taking pot shots at us. They come because asteroid hunters are improving their searches. “We’re getting better at spotting asteroids, and we expect many more discoveries in the future,” says Gareth Williams, associate director of the Minor Planet Center.
The three latest objects were all spotted first by the Mount Lemmon Survey, which searches for asteroids with a renovated 1.5-metre telescope in Arizona. Two asteroids were only a few metres in diameter, and the smallest was only about a meter, making spotting and tracking the objects in space an impressive achievement.
So what’s to worry about? We didn’t see 2008 US or 2008 TS26 until a few hours after they made their closest approaches to the Earth because both were heading out from the Sun – and were lost in its glare – when they crossed the planet’s orbit. That’s no big deal because if such small objects hit the atmosphere, they would have streaked harmlessly across the sky as fireballs, like 2008 TC3. But it does remind us that asteroid hunters have a blind spot, and can’t see objects coming from inside the Earth’s orbit.
That blind spot is one reason it’s important to catalogue and track Earth-crossing asteroids large enough to crash to the surface. Our brief observations of 2008 US didn’t give enough information to calculate its orbit precisely, and Williams says we’re not likely to see it again.
The good news is that bigger, more dangerous asteroids are brighter and easier to follow in the sky, so most of their orbits are known too well for them to surprise us by coming from out of the Sun. Next year, Canada will launch a small satellite that developers hope can spot asteroids inside the Earth’s orbit. US astronomers have proposed orbiting a satellite around Venus to hunt for such asteroids. But can we ever completely eliminate the danger of unknown objects?
Jeff Hecht, Boston correspondent
On the Trail of 2008 TC3
Credit: Mohamed Elhassan Abdelatif Mahir (Noub NGO), Dr. Muawia H. Shaddad (Univ. Khartoum),
Dr. Peter Jenniskens (SETI Institute/NASA Ames)
Explanation: On October 7, the early dawn over northern Sudan revealed this twisted, high altitude trail. Captured in a video frame, the long-lasting persistent train is from the impact of a small asteroid cataloged as 2008 TC3. That event was remarkable because it was the first time an asteroid was detected in space before crashing into planet Earth’s atmosphere.
In fact, after astronomers discovered 2008 TC3, the time and location of its impact were predicted based on follow-up observations. Later, the impact predictions were confirmed by sensors, including a Meteosat-8 image of a bright flash in the atmosphere.
Astronomers are now hoping for more reports of local ground-based observations of what must have been a brilliant meteor streaking through Sudan’s night sky. Additional reports could improve the chances of recovering meteorites.
http://antwrp.gsfc.nasa.gov/apod/ap081108.html
November 18, 2008
New Telescope on the Lookout for Near Earth Asteroids, Comets
Written by Nancy Atkinson
A prototype telescope with an enhanced ability to find moving objects will soon be operational, and its mission will be to detect asteroids and comets that could someday pose a threat to Earth.
The system is called Pan-STARRS (for Panoramic Survey Telescope and Rapid Response System) located on Haleakala mountain in Maui,Hawaii, and is the first of four telescopes that will be housed together in one dome.
Pan-STARRS will feature the world’s largest and most advanced digital camera, providing more than a fivefold improvement in the ability to detect Near Earth Asteroids and comets.
“This is a truly giant instrument,” said University of Hawaii astronomer John Tonry, who led the team developing the new 1.4-gigapixel camera. “We get an image that is 38,000 by 38,000 pixels in size, or about 200 times larger than you get in a high-end consumer digital camera.”
The Pan-STARRS camera will cover an area of sky six times the width of the full moon and it can detect stars 10 million times fainter than those visible to the naked eye.
Full article here:
http://www.universetoday.com/2008/11/18/new-telescope-on-the-lookout-for-near-earth-asteroids-comets/