"The dinosaurs could tell you how a serious asteroid hit turns out - except they can't because they're all dead, thanks to a 6-mile asteroid that crashed off the Yucatan peninsula 65 million years ago." - Jeffrey Kluger, 'The Man Who Guards The Planet', TIME, June 9, p. 34.
The recent news that Obama has done an "about face" and decided to ask for money to arm "moderate" Syrian rebels boggles the mind. Here is an intelligent man who merely two days earlier had emphatically told interviewer Nora O'Donnell that such a move - expecting any real results- would be a "fantasy". As Bill Maher asked last night: How do we even know those to whom we deliver the purchased arms will be the ones for whom they're intended? Do we have a special 'moderate rebel' detector? Likely not and the arms will simply end up in ISIS' hands just like the American arms dumped by fleeing Iraqi army troops barely 2 weeks ago.
Instead of pissing away $500m on nonsense, I have a better recommendation - one for which planetary astronomers have been screaming. That is, $500m will be the exact amount needed to purchase an infrared telescope to monitor asteroids in space, especially the ones most likely to take us out - like the dinosaurs.
This is not the stuff of science fiction and any human with more than air between the ears ought to have received a wake up call after the Chelyabinsk object struck near that Russian town on the morning of February 15, 2013. The incoming object (small for an asteroid) - ended up injuring 1,600 people and damaging 7,300 buildings. And this wasn't even a direct hit! The object was 66 ft. wide and exploded with the force of 33 Atomic bombs on the scale of the Hiroshima weapon. The only thing that prevented more damage is that the object exploded in the atmosphere (air burst).
To be sure, there's little that we can do to protect against these relatively minor objects. They are simply too small and if they come in from the direction of the Sun, virtually impossible to pick up before they're literally on top of us. This was the case with the Chelyabinsk object. Currently, NASA's office of Near Earth Objects (NEO) is tracking some 600,000 asteroids but it is a core of 11,000 so-called near Earth objects that garner the most attention. This subset is defined as those asteroids that come within 1.3 AU (1 AU = 93 million miles) . To qualify as what's known as a potentially hazardous asteroid, the object must be at least 460 ft. in diameter and come within 0.05 AU of Earth (or 4.65 million miles). Currently, NASA knows of 1,500 of these objects.
Large asteroids that actually cross the Earth's orbit are the most dangerous, the so-called Apollo objects. How they emerge as a threat, when their orbits are perturbed, is shown in Fig. 2 above, for Icarus (Fig 1. shows a large asteroid, Gaspra, that - if it struck Earth - would annihilate all life on it)
What makes any large asteroid dangerous, is its mass in combination with its relativity velocity or speed of approach. Thus, large Apollo objects and other asteroids would typically have relative velocities from 11,000 to 30,000 meters per second, or about 6.8 to 19 miles per second. For an asteroid with a 1 kilometer (0.62 mile) diameter, at a density three times that of water, this would generate an equivalent energy on impact of one million Hiroshima sized atomic bombs. Since the Hiroshima explosion was equivalent to 13,000 tons of TNT, this means a larger asteroid would generate an explosive force of 13 thousand megatons. This already is roughly equal to the total equivalent of all U.S. nuclear warheads.
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For a ten kilometer asteroid (roughly 6 miles across) the explosive equivalent would translate into 13 million megatons. This would dwarf all man-made nuclear stocks and warheads, and is rightfully called ‘planet –killer’. It is specifically asteroids of this magnitude that keep asteroid searchers up late at night.
In a recent '60 Minutes' segment on killer asteroids, an appeal was made by two asteroid trackers for a special infrared telescope capable of tracking large asteroids in deep space. The goal would be to identify them and provide a time horizon long enough to be able to deflect them and prevent them from colliding with Earth. (The use of nukes, such as in flicks like "Armageddon", is not fancied by the experts because an imprecise blast could merely reduce one very large object to many smaller ones - turning a bomb into a 'cluster bomb')
Thus, the current thinking leans to long term deflection of large objects - but that requires a lot of time because such deflections amount to tiny fractions of a degree per year. To give an example of one possible method, consider the YORP Effect. This is named after Yarkovsky-O'Keefe-Radzievskii-Paddack – or the trio of physicists that discovered it. It occurs when photons from the Sun are absorbed by a body and re-radiated as heat. In the process, two forces influence the object: one from the impact of the photons, providing a tiny push, and the other as a recoil effect when the object emits the absorbed energy. For small, irregularly shaped objects , YORP can cause measurable changes in motion.
In 2009, I attended a conference sponsored by the Dynamical Astronomy Division of the American Astronomical Society that featured a paper entitled; ‘Analytic Theory of the YORP Effect for Near –Spherical Objects'. .At that time torques of the form:
dt = r x F dS
were considered, where r is the radius vector and F the force supplied. The element of asteroid surface area is dS. The situations were confined to the cases therefore, where the impinging solar radiation was at right angles to the asteroid’s spin axis. Three separate detections of the effect were announced, including for a nearly spherical object (1998 KY), and on two more irregular objects, (1862 Apollo, and 25143 Itokawa).
In the case of the Apollo object the observed effect was approximately 3.0 x 10 -4 deg/day, vs. the theoretically –predicted YORP effect magnitude of 2.6 x 10 -4 deg/day. Earlier, Cornell graduate student Patrick Taylor and assistant professor of astronomy Jean-Luc Margot mapped the shape and located the spin pole of a 100-meter-diameter (about 300 feet) near-Earth asteroid called (54509) 2000 PH5 (abbreviated to PH5) between 2001 and 2005, using radar at the National Science Foundation's (NSF) Arecibo Observatory in Puerto Rico and NASA's Goldstone telescope in California.
The results suggest it may be possible to use an artificial YORP effect, generated over time, to deflect a significantly large asteroid. The strategy might include high-powered lasers mounted on massive spacecraft to deliver one deflecting force.. It may well require using powerful lasers in tandem, say along the lines of a recently -developed high-powered 50kW laser designed by a German firm (http://www.dailymail.co.uk/sciencetech/article-2259639/The-groundbreaking-Star-Wars-laser-shoot-drone-sky-TWO-MILES-away.html
Combined with other sources of radiant energy directed at the surfaces of the asteroid this could conceivably create an artificial YORP Effect. Then, say in the case of an irregularly shaped object, one might alter its spin axis as well as motion- trajectory, when used in conjunction with the lasers.
Combined with other sources of radiant energy directed at the surfaces of the asteroid this could conceivably create an artificial YORP Effect. Then, say in the case of an irregularly shaped object, one might alter its spin axis as well as motion- trajectory, when used in conjunction with the lasers.
How long a time horizon might be needed, assuming we can get an infrared telescope in place in an expeditious manner? (And not piss the money away on stupidity). Given that no proper asteroid-deflecting space craft yet exists (we pissed most of the money that could have built one on stupid 'wars' in Iraq and Afghanistan) and it may take five years minimum for its design and construction, we'd like need 10 years. This is according to NEO asteroid tracker Don Yeomans. Thus, ten years is probably the minimal time needed between the time of discovery of a killer rock that has our name on it, and effecting a deflection that removes the threat.
Right now, without even a veneer of protection, things don't look sanguine. Simulations of a killer asteroid impact in 2021 have been conducted by DARPA (Defense Advanced Research Project Agency) and FEMA - using war gaming techniques - and nearly all outcomes disclose we're toast, depending on the exact size of the object. The larger the object the worse the outcome, including worst of all: nuclear winter killing off all crops within 6 months leading to the de facto end of humans. Just like the dinosaurs.
The U.S., while it is pressing other nations to get more involved (the U.S. is doing 98 percent of the asteroid tracking) still needs to get its own act together and cease squandering resources on stupid military adventures. Instead, it needs to apply money and resources to asteroid intercepting and deflecting space craft (and that infrared telescope) instead.
On the good side, since the Chelyabinsk object struck, the budget for searching out dangerous asteroids has been doubled to $40m - but this is still a drop in the bucket. If we're serious about not getting creamed into oblivion we will first take that 1/2 billion dollars Obama wants to put toward Syrian rebels to an asteroid detecting telescope instead. Then, we will shut down the Afghan fiasco and put that 1/2 billion to 1 billion toward expediting asteroid deflecting spacecraft design.
Our lives may depend on it. While it's true that not all forms of life succumbed when the dinosaur-killing event occurred 65 million years ago, the dominant form was taken out. This is an object lesson we dare not ignore or dismiss given we are the heirs apparent to the dinos' once kingly position. Hence the goal is simple: avoid falling into the same fate.
If we are really homo sapiens, as opposed to homo moronicus, we will get on with it!
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