[Edward Lu is with the B612 Foundation “Why Move an Asteroid?” Testimony before the Subcommittee on Science, Technology and Space of the Senate Commerce Committee, 7 April 2004, Astrobiology. http://www.astrobio.net/index.php?option=com_retrospection&task=detail&id=972] Why does the asteroid need to be moved in a "controlled manner"? If the asteroid is not deflected in a controlled manner, we risk simply making the problem worse. Nuclear explosives for example risk breaking up the asteroid into pieces, thus turning a speeding bullet into a shotgun blast of smaller but still possibly deadly fragments. Explosions also have the drawback that we cannot accurately predict the resultant velocity of the asteroid -- not a good situation when trying to avert a catastrophe. Conversely, moving an asteroid in a controlled fashion also opens up the possibility of using the same technology to manipulate other asteroids for the purposes of resource utilization.
[Michael Paine is the NSW Coordinator at the Planetary Society Australia “To Nuke or To Nudge,” Space.com, 11 February 2000, http://www.space.com/businesstechnology/technology/nudging_not_nuking_000211.html] An asteroid is heading for Earth. With just days to go before the collision a beefed-up space shuttle is sent to intercept it. A brave team of astronauts and oil-rig workers drills deep into the space rock, plants a nuclear bomb and blows it in two. The two halves fly apart and miss the Earth. Dream on! The idea of blowing up an asteroid makes for good movie scripts, but is not the way to do it in the real universe. Many of the fragments would remain on a collision course and like the blast from a shotgun; the fragments can do up to ten times as much damage as the original, intact object. Nuclear deflection is normal means and it fails Harris--98
[Alan W. Harris is with the Earth and Space Sciences Division of the Jet Propulsion Laboratory “Planetary science: Making and braking asteroids,” Nature, 393, 4 June 1998] Perhaps the most interesting aspect of this work for the general public is the implication for defence against asteroid impacts on the Earth. If an asteroid were found to be on a collision course with the Earth, could we avoid it? The front-running technique is to explode a nuclear bomb some distance from the asteroid, vaporizing a thin layer of its surface on one side, and thus giving it a nudge. But most studies8 of this process have suffered from the spherical chicken problem, modelling the offending asteroid as a coherent solid body rather than a loose collection of debris.The new work may mean that deflecting an asteroid from a collision course would be more like clearing a landslide off the road than pushing a boulder aside. If the only thing holding the body together is gravity, then one cannot apply an impulsive change in its motion greater than the escape velocity from the surface without disrupting the body into many pieces. This means a kilometre-sized body can be given a change of course of only about a metre per second. Such a small impulse would have to be applied a fair fraction of a year before the projected time of collision in order to accumulate a change of path of a couple of Earth radii. The smaller the object, the smaller the impulse allowed, so the concept of a 'Star Wars' type shield protecting the Earth from imminent impacts is seriously flawed; better to discover asteroids far in advance in an orderly survey, allowing plenty of time to respond.
Bureaucratic inertia means no deflection Schweickart--04
[Russel Schweickart is Chairman of the B612 Foundation, “Asteroid Deflection: An International Challenge,” Presented at the World Federation of Scientists meeting of the Multidisciplinary Core Group on Planetary Emergencies, Rome, Italy, December 2004]
In any event, the minimal policy decision involved in any asteroid deflection would be whether to deflect it at all or simply suffer the consequences of the nominal impact. If the incoming asteroid were on the order of 100 meters in diameter the resultant impact would be on the order of 80 MT and the resulting damage could lie entirely within the borders of one nation. If this nation were not a space faring nation who would respond to a request to mount such a mission? Conversely if the nominal impact were located within the borders of a space faring nation, would the risk to others along the deflection risk path deter that nation from mounting a deflection mission? Who will make these decisions? Who will pay for a deflection mission? Who will be charged with the responsibility for executing such a mission? How is liability to be assigned? Who will trade off local devastation vs. placing many remote lives at slight risk? Who will determine the planning criteria? Who will monitor and/or control the deflection mission? These and many other difficult and critical policy questions are implicit in the concept of asteroid deflection. In all but the exceptional case the choices to be made involve several, if not many, nations. The entire subject is planetary in scope since asteroid impacts may (and eventually will) strike anywhere on the globe. An Alternative to Institutional Inertia The easiest and perhaps most likely course of action for international institutions facing questions of this kind is to simply avoid them. And yet, for those involved in the Spaceguard Survey and others informed on the subject it is clear that addressing these choices only after the announcement of a pending impact will result in great contention, self serving argument, and power politics. Once a specific IP is determined the hope for rationale, equitable policies emerging from such a belated undertaking becomes futile. In the limit an asteroid impact which destroys all human civilization is possible, though extremely improbable. No other natural disaster is capable of such destruction, and yet this natural hazard, unlike most others, can actually be prevented by human intervention. We therefore face the daunting challenge of convincing the international community to plan for a highly unlikely but devastating global event, and to do it now. Yet many more immediate problems involving the lives of millions of people face the international community on virtually a continuous basis. It is “natural” to avoid this issue.Risk situations characterized by extreme infrequency and devastating consequences are difficult forindividual human beings, let alone bureaucratic institutions to handle. This is even more the case when the questions to be addressed are so intractable and without precedent. Yet the time for rational policy to be developed to guide behavior and prepare for such an eventuality is prior to the discovery of an asteroid actually bound for an impact. The reality we face, however, is that there is about a one in twenty chance that within the next decade or so we may in fact discover such a pending impact. Worse still, from the standpoint of alarming the public, is the much higher likelihood that in completing the inventory of NEOs down to 100 meters, the astronomical community will in fact discover one or more objects destined to pass within several Earth radii. The problem in this case will arise in that it may take many years before the telescopic observations are able to distinguish between this near miss and an impact. During this period of time no one will be able to state with certainty whether or not an impact is coming. This circumstance, with perhaps a 50/50 likelihood of occurrence, will be extremely frustrating to the professionals and alarming to the public.