Supplemental section of the file (for printing purposes, starts at p. 102)

We can’t just nuke an asteroid, the study is very precise

A new study from New York City College of Technology sheds light on how a deflection strategy would work best in order to avoid collision with giant space objects such as asteroids. "A collision with an object of this size traveling at an estimated 30,000 to 40,000 mile per hour would be catastrophic," said NASA researcher and New York City College of Technology (City Tech) associate professor of physics Gregory L Matloff. His advice is to "either destroy the object or alter its trajectory." In 2029 and 2036, the asteroid Apophis (named after the Egyptian god of darkness and the void), at least 1,100 feet in diameter, 90 stories tall, and weighing an estimated 25 million tons, will make two close passes by Earth at a distance of about 22,600 miles. According to the researcher, diverting objects such as these is a better option than exploding them as the debris itself could bathe Earth in a radioactive shower. His study indicates that an asteroid could be diverted by heating its surface to create a jet stream, which would alter its trajectory, causing it to veer off course. And to do that, one needs to know how deeply the light would need to penetrate the NEO's (near Earth object) surface. "A beam that penetrates too deeply would simply heat an asteroid but a beam that penetrates just the right amount - perhaps about a tenth of a millimeter - would create a steerable jet and achieve the purpose of deflecting the asteroid," said Matloff. Matloff and his colleagues have been experimenting with red and green lasers to see how deeply they penetrate asteroidal rock, using solid and powdered (regolith) samples from the Allende meteorite that fell in Chihuahua, Mexico in 1969. "For certain types of NEOs, by Newton's Third Law, the jet stream created would alter the object's solar orbit, hopefully converting an Earth impact to a near miss," Matloff stated. However, he cautioned, "Before concluding that the SC will work as predicted on an actual NEO, samples from other extraterrestrial sources must be analysed." Matloff presented a paper on the results of the City Tech team's optical transmission experiments, "Optical Transmission of an Allende Meteorite Thin Section and Simulated Regolith," at the 73rd Annual Meeting of the international Meteoritical Society, held at the American Museum of Natural History and the Park Central Hotel in New York City.

NW Fail - Fragmentation

Even dust fragments cause an explosion on Earth

Nemchinov et al. ‘8 (Ivan Nemchinov, Valery Shuvalov, & Vladmir Svetsov, Institute for Dynamics of Geospheres, Russian Academy of Sciences, “Main Factors of Hazards Due to Comets and Asteroids,” in Catastrophic Events Caused by Cosmic Objects, pg 58-59)

If the NEO cannot be deflected away from Earth’s orbit as a whole object, it seems reasonable to fragment it into several or a large number of pieces, or even pulverize it. Estimates by Simonenko et al. (1994) show that if a nuclear explosion pulverizes a small asteroid at distances of about 0.01 AU, i.e., 1.5.106 km from the Earth, the average density of particle flow at the Earth will be from i0 to 10—6 g.crn3. The characteristic dimension of such a cloud striking the Earth is on the order of 102_103 km. One could think that fine asteroidal dust will simply evaporate at high altitudes in the Earth atmosphere, as small meteors do, and not produce any damage. However, the dust particles will not penetrate the atmosphere independently one from another, they will act collectively as a fluid-like stream. A huge explosion will occur in the atmosphere, producing both a radiation impulse and a shock wave at the Earth’s surface. Assume that the average size of fragments is much larger, e.g., 1—2 m. As observations of bolides show, such meteoroids decelerate and produce bright flashes at altitudes of 25—30 km. The diameter of a meteor trail behind such a body is about 0.1 km. The penetration of asteroidal fragments into the atmosphere will be independent from one another if the distance between them is larger. If a 200-rn asteroid is broken into 2-rn-diameter fragments, their number is 106. Therefore, the total cross-section of all wakes, if the fragments simultaneously enter the Earth’s atmosphere will be 0.3.1010 m2. This is equivalent to a circle with a radius of 30 km. If each fragment emits radiation like a typical 1—10 m bolide, i.e., emits about 10% of its kinetic energy, the total radiated energy will be about 4.1011 MI, or the fluence per unit area will be 104J.cm2. The estimated fluence substantially exceeds the fire ignition threshold in the case of fine weather. This model assumes that the fragments decelerate at altitudes 25—30 km and cover an area with a size of the same order. Shock waves from all bolides will unite in the atmosphere and the amplitude of a shock wave at the Earth’s surface will be large enough to break up buildings. Numerical simulations of the entry of a rarefied water vapor stream with a radius of 10 km and density of 102kg.m3 to the atmosphere were made by Teterev (1998). For the entry velocity of 10 km.s, the initial kinetic energy of a stream was about 250 Mt TNT. Strong deformation of the stream begins at altitudes of 40—50 km. In 18 s a shock wave separates from the water vapor cloud. The water mass decelerates at altitudes of about 20 km. The shock wave reaches the Earth’s surface in 23 s. Its amplitude is sufficient to produce strong devastation on the ground. After the impact heated atmospheric gas and vapor expand to the upper atmosphere, and in ‘300 s fall back at a distance of 1,000 km. The atmosphere is heated at altitudes of 70—100 km and the ionospheric layers oscillate. Therefore fragmentation into fine powder or rather large fragments cannot save on-the-ground objects and population. The size of asteroidal fragments depends on the yield of a nuclear device and the structure, shape, porosity, and strength of a cosmic body. Continuation of observations from ground telescopes or satellites and space missions is essential for obtaining such data for small cosmic objects.

Nuclear explosion fragments the asteroid, making the impact worse

Prantzos ‘2k

(Nikos, researcher at the Paris Institute of Astrophysics, Our Cosmic Future: Humanity’s Fate in the Universe, p. 199)

Future civilizations will no doubt find a way of protecting themselves against asteroid impacts on Earth. However, no effective means of defence is known today. In the case of a relatively small object, we could only organize an evacuation of the region surrounding the point of impact. Unfortunately, the exact location of this point would only be known with any accuracy a few days before impact. In the case of massive objects the time factor is of capital importance. An effective parry could not be envisioned in under a few months, or even years. In science fiction, there is a widespread idea that megatonne nuclear weapons could be used to explode the projectile. But this would serve no useful purpose. An object of this mass cannot be pulverised. At best, it would be shattered into several dozen pieces, each measuring hundreds of metres in diameter, and these would continue along their fateful trajectories. This is precisely what happened to comet Shomaker-Levy in 1994. It had long been fragmented by Jupiter’s gravitational forces and the various pieces ploughed into the surface in quick succession. The destruction resulting from a series of projectiles of these dimensions showing down on Earth would be even more disastrous than if the asteroid had struck intact.

Nuclear weapons will fragment the asteroid, not deflect it

Griffin ‘4

(Dr. Michael, Head of the Space Department John Hopkins University Applied Physics Lab, “Near-Earth Objects,” testimony before the Committee on Senate Commerce, Science and Transportation Subcommittee on Science, Technology, and Space, Apr.7 CQ, lexis)

The deflection technologies available today, which are chemical rockets and nuclear weapons, both have limited abilities to slow down or speed up an asteroid. A 100 m object has a mass of the order of 1 million tons, and a 1 km object has a mass of the order of 1 billion tons. To prevent an object from colliding with Earth, it must be sped up or slowed down by about 7 cm/s (about 1/6 of an mile per hour) divided by the number of years in advance that the change is applied. The fuel that can be contained in a medium-sized scientific spacecraft could successfully deflect a 100 m body if it were pushed about 15 years in advance. The Space Shuttle's main engines and the fuel contained in the large external tank could successfully deflect a 1 km diameter object if it were applied about 20 years in advance. Nuclear weapons carry much greater impulse for their mass. However, they deliver that impulse so quickly that they are more likely to break up the body than to deflect it. Because NEOs are in their own orbits around the Sun, the pieces of a disrupted object will tend to come together one half of an orbital period later. Therefore, the successful use of nuclear weapons for deflection will require the development of techniques for slowing the delivery of the impulse to the NEO and will probably also require many small weapons to be used to deflect a single NEO.

Nuclear explosion will fragment the asteroid and increase the impact

Schweickart ‘4

(Russell, Chair of the B612 Foundation, former astronaut, Executive Vice President of CTA Commercial Systems, Inc. and Director of Low Earth Orbit (LEO) Systems and research, and scientist at the Experimental Astronomy Laboratory of the Massachusetts Institute of Technology (MIT), “Asteroid Deflection; Hopes and Fears,” Aug., Presented at the World Federation of Scientists Workshop on Planetary Emergencies, Erice, Sicily, August 2004 http://www.b612foundation.org/papers/Asteroid_Deflection.doc)

The hard options consist of various forms of nuclear explosion as well as that of direct (or kinetic) impact. In each case, however, to be effective the resultant force must be applied along the NEA’s velocity vector, with the exception of two cases. If one considers the option of fragmenting the NEA a viable option (i.e., blowing it to pieces) then the direction of impulse becomes meaningless. While there are many uncertainties regarding the effect of a nuclear explosion intended to fragment an asteroid (generally assumed to be a sub-surface burst) it seems clear that, given a large enough nuclear weapon, the fragmentation could be achieved. Arguments have been made from the first discussion of this option, however, that such a strategy would be unwise since the possibility exists that the resultant fragmentation could actually increase the overall threat and not eliminate it. No general answer to this debate will likely evolve since it is highly dependent on the structural character of the asteroid in question.

Nuclear weapons increase the impact by fragmenting the NEO

Spaceguard - No Date

(United Kingdom Spaceguard Centre, Mitigation, http://www.spaceguarduk.com/mitigation)

The possibility of destroying potential impactors, probably with high yield nuclear weapons, has been studied in some detail. With the current lack of detailed knowledge of the exact composition of particular objects, and their structural strength, there is an element of doubt as to the effectiveness of this course of action. The fear would be that incomplete disruption of the object would subject the Earth to multiple impacts from pieces of the original body. The effects of transforming a cannon ball into a cluster bomb could be more far-reaching than the original threat.

Nuclear weapons increase the impact by fragmenting the NEO

Task Force ‘2k

(British National Space Centre, Report of the Task Force on Potentially Hazardous Near Earth Objects, http://www.spacecentre.co.uk/neo/report.html)

To try to destroy an asteroid or comet in space by a single explosive charge on or below its surface would risk breaking it uncontrollably into a number of large pieces which could still hit the Earth, doing even more damage. A more promising method would be to fly a spacecraft alongside the object, perhaps for months or years, nudging it in a controlled way from time to time with explosives or other means. This relatively gentle approach is particularly important because many asteroids and comets are held together only by their own very weak gravitational fields. The longer the time before impact, the more effective even a small nudge would be. This is not science fiction. When NASA launches its Deep Impact mission to comet Tempel 1 in 2004, the spacecraft will eventually release a half tonne lump of copper to cause a huge crater in the comet. Although this is not the objective, the result will also be to deflect the comet’s orbit. However, the deflection in this case will be small in comparison to that required to deal with a real threat.

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