Impacts from space debris are much in the news again. The death of Arthur C. Clarke plays a role in at least some of the interest, the New York Times reprinting an op-ed piece the writer did for that paper back in 1994. This was not long after Shoemaker-Levy demonstrated what a cometary impact might do even to a massive gas giant, getting people thinking about the options if we discovered an asteroid or comet heading our way. They might also have been reminded of Rendezvous with Rama.
Clarke had discussed asteroid impacts in the early pages of the 1973 novel, setting up Project Spaceguard as a defense mechanism — a 1992 NASA workshop report on near-Earth object detection honored Clarke by being named the Spaceguard Survey. In the op-ed, Clarke made it clear what he thought the stakes were:
In view of the number of collisions that have taken place in this century alone — most notably, a comet or asteroid that exploded in 1908 in Siberia with the force of 20 hydrogen bombs — there is a very good case for a global survey of the possible danger, particularly as the shared cost among nations would be negligible compared to most national defense budgets. (Incidentally, historians might also be advised to undertake some surveying. Just as the numerous meteor-impact craters on Earth were never found until we started looking for them, so there may have been disasters in history that have been misinterpreted. Sodom and Gomorrah have a good claim to be meteorite casualties; how many others are there?)
Interesting in light of a clay tablet discovered in the ruins of Nineveh by Austen Henry Layard some 150 years ago. Itself more than 2500 years old, the tablet is apparently a copy made by an Assyrian scribe of a much older tablet. Showing drawings of constellations amidst cuneiform symbols, it is being put forth as evidence of a large fireball passing over Mesopotamia and observed by Sumerian astronomers. Alan Bond (Reaction Engines Ltd.) and Mark Hempsell (Bristol University) argue in a new book that the tablet records events in the sky on June 29, 3123 BC.
If Bond and Hempsell are right, the trajectory of a large object traveling across Pisces can be made out, consistent with an impact near the town of Köfels in the Austrian Alps. Tens of thousands might have died in the impact of this object, thought to be over a kilometer in diameter. A low incoming angle of six degrees would explain the lack of a crater at Köfels, the asteroid striking a mountain eleven kilometers from the village and exploding.
A fireball would have resulted, but no crater. The area is known to have endured a massive landslide some 500 meters thick and five kilometers in diameter, but the lack of a crater had puzzled previous scientists. Puzzled them enough, in fact, that many geologists think no impact was involved. Even more questionable is Bond and Hempsell’s suggestion that energy from the fireball traveled as a back plume out over the Mediterannean, re-entering the atmosphere in ways consistent with the destruction of the very Sodom and Gomorrah Clarke cites. Says Hempsell:
“The ground heating, though very short, would be enough to ignite any flammable material, including human hair and clothes. It is probable more people died under the plume than in the Alps due to the impact blast.”
This is a fascinating theory and I’m all for examining the historical record for possible references to asteroid impacts, but the interpretation of cuneiform tablets is exceedingly difficult work subject to numerous different and competing analyses. Let’s wait to see what specialists in the area have to say about this particular interpretation. NASA’s David Morrison also notes that we should at least look for computer modeling to demonstrate the possibility of the back plume wreaking destruction in the Sinai, an idea he says ‘sounds pretty incredible.’
Although dubious, I’d like to see this story work out for more than just scientific reasons. After all, Alan Bond’s name should be familiar to Centauri Dreams readers. Along with his rocketry work at Rolls Royce and later fusion studies for the UK Atomic Energy Authority, Bond was the lead author of the Project Daedalus final report. I defer to no one in my admiration for the work of the British Interplanetary Society on the first full-fledged engineering study of a starship, a battered photocopy of which sits about eight feet away from me, laden with annotations.
Considerably less questionable than Köfels is new evidence of the largest meteorite ever known to have struck Britain, falling some 1.2 billion years ago near the town of Ullapool. Those of us who travel often in Scotland can attest to the beauty of Ullapool and environs today, but 1.2 billion years ago ejecta from this strike were apparently scattered over an area at least fifty kilometers across. Here’s a bit of the confirmatory evidence, presented by Ken Amor (Oxford University):
“Chemical testing of the rocks found the characteristic signature of meteoritic material, which has high levels of the key element iridium, normally only found in low concentrations in surface rocks on Earth. We found more evidence when we examined the rocks under a microscope; tell-tale microscopic parallel fractures that also imply a meteorite strike.”
Image: Artist’s impression of a large meteorite hitting the Earth. The crater from the strike at Ullapool was quickly buried in sandstone, preserving evidence of the impact. How many other craters from large meteorites or even asteroids remain to be discovered? Credit: © MIKE AGLIOLO/SCIENCE PHOTO LIBRA.
The paper here is Amor et al., “A Precambrian proximal ejecta blanket from Scotland,” Geology Vol. 36, Issue 4 (April 2008), pp. 303-306 (abstract). The book on the possible strike at Köfels is Bond and Hempsell, A Sumerian Observation of the Köfels’ Impact Event (Alcin Academics, 2008). Whether or not the latter is borne out by subsequent research, it’s good to see the subject of Earth impacts continuing to make headway in the popular press, perhaps evidence that the need for planetary defense planning in the Arthur C. Clarke mode hasn’t been entirely lost on editors busy with more short-term projects.
I have posted about this recently myself: http://dad2059.wordpress.com/2008/04/01/ancient-sumerians-record-meteor-event/
But not in relation to Spaceguard, fact or fictional. It’s a natural fit though, an asteroid defense network that actually has ‘teeth’ is a realistic goal.
Too bad the military-industrial-complex finds murder and genocide more profitable.
They ought to reconsider than line of thought. One good size asteroid or comet hitting the Earth and they won’t have anymore customers buying their deadly wares.
That’s the trouble with corporations, they only think in three month chunks!
Wikipedia (already) links to an article in TimesOnline: http://www.timesonline.co.uk/tol/news/uk/science/article3649054.ece
Would all the money be diverted from religious institutions to astronomy and asteroid research, now?
Hans
Um. I’m perfectly happy to accept that there have been a plethora of impacts on the Earth, some even in almost current times, and that the risks from such events are large. But, any interpretation of archaeological materials by individuals with a wish to find evidence of impacts, visitors or whatever from outer space is suspect, suspect, suspect! Alan Bond and Co. should be aware of the difficulties!
Identification of events via geological records is one thing; imposing 21st Century enthusiasms on the scant records left by ancient peoples is a disservice to all concerned.
Bob Shaw
I’m fully in agreement with Bob on this. The art of interpretation re cuneiform is as tricky as working out some of the variants of string theory, and I would be a lot more comfortable with this particular view if there were any solid consensus from scholars of the Sumerian period on what’s on this particular tablet. From ancient Sumeria to Austria and back to the Sinai seems two jumps too far to me, but let’s see if the theory gets any traction from linguists.
A bit too close to von Däniken for comfort… add the fact that the tablet was inscribed in 700 BC, containing events allegedly taking place in 3,000 BC. If it’s a copy of an older tablet, how did the scribe know that the event happened in 3,000 BC?
Also, I sniffed around about Köfels — apparently, the landslide does not require an impact for explanation, and dating places it around 10,000 BC (+/- 1,000), much earlier than the 3,000 BC date proposed by this group.
The part of me that writes poetry and fiction simply loves all-encompassing explanations, from string theory to legends attributable to natural events. However, the scientist in me is aware, however reluctantly, that truth (data) trumps beauty (elegant theories).
Hi Folks;
This is why we must learn to track and deflect or divert even small incomming comets or asteriods. Bear in mind that the asteriod which hit Tunguska Siberia had an explosive yield on the rough order of 5 to 10 megatons. An airburst of a vaporizing asteriod or comet over a major metropolitan center with a yield of 25 megatons based on info provided by the Department of Homeland Security’s Web Site for a 25 megaton nuclear airburst would have the following effects.
Upon detonation of the meteor at an airburst hieght of 17,500 feet, a huge fireball will form. Within a range of about 6.8 miles from the point on the ground directly beneath the blast, virtually nothing remains standing except for perhaps the shells of some of the strongest poured reinforced concrete structures near the outer periphery of this region. The airblast pressure at a radius of 6.8 miles would be about 15 to 20 pounds per square inch or up to about 1.5 tons per square foot. The immeadiate fatality rate will be over 98 percent. Some folks will survive at least initially because they were under ground in subways tunnels and the like. At a distance of about 10.8 miles from the hypocenter, the over pressure will still be about 5 PSI and still, their will be virtually nothing standing between the 6.8 mile contour and the 10.8 mile contour. Fifty percent of the persons within this second ring die immediately, another 45 percent are so seriously injured that virtually all of them will die in minutes or hours without emergency medical treatment which will be completely absent. Five percent will at least initially be uninjured or injured superficially. The 2 PSI contour overpressure will extent out to about 20 miles, a pressure which is still great enough to seriously damage domestic homes. In this ring, 5 percent of the persons will be killed immeadiately and 45 percent will be injured, many of the injured requiring immeadiate medical attention. In addition, fatal third degree burns can be inflicted on those out in the open as far away as 35 to 40 miles from the blast hypocenter. In actuality, it is highly likely that a firestorm will quickly develop ingulfing every thing within a 15 mile radius of the hypocenter with fatalities approaching 100 percent and flame temperatures as high as or exceeding in some cases 2,000 degrees C. So we must get those comets and asteriod before they get us.
Thanks;
Jim
A capability to deflect an asteroid shouldn’t be thought of as something that’d just sit out there until needed, it implies affordable access to orbit, which would open the door for space-based solar power and ease our energy problems. And opening a new frontier would ease some spiritual problems.
Tim, my contention is that developing the needed infrastructure to deflect an asteroid necessarily opens up the outer Solar System for exploration by manned crews and pushes our propulsion technologies to the point where we can move into the Edgeworth/Kuiper belt. Long-term, defending against the impact threat could be a powerful incentive to advance the state of the art in everything from solar sails to fusion propulsion, making an interstellar crossing a bit less remote.