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Defending Planet Earth: Near-Earth-Object Surveys and Hazard Mitigation Strategies
characteristics of at least 90 percent of potentially hazardous NEOs larger than 140 meters in diameter by the end of year 2020? Specific issues to be considered include, but are not limited to, the following:
What observational, data-reduction, and data-analysis resources are necessary to achieve the Congressional mandate of detecting, tracking, and cataloguing the NEO population of interest?
What physical characteristics of individual objects above and beyond the determination of accurate orbits should be obtained during the survey to support mitigation efforts?
What role could be played by the National Science Foundation’s Arecibo Observatory in characterizing these objects?
What are possible roles of other ground- and space-based facilities in addressing survey goals, e.g., potential contributions of the Large Synoptic Survey Telescope (LSST) and the Panoramic Survey Telescope and Rapid Response System (Pan STARRS)?
Task 2: NEO Hazard Mitigation
What is the optimal approach to developing a deflection capability, including options with a significant international component? Issues to be considered include, but are not limited to, the following:
What mitigation strategy should be followed if a potentially hazardous NEO is identified?
What are the relative merits and costs of various deflection scenarios that have been proposed?
In response to this assignment from Congress, the National Research Council created a steering committee—the Committee to Review Near-Earth Object Surveys and Hazard Mitigation Strategies—and two panels (one for each task: the Survey/Detection Panel and the Mitigation Panel) to undertake a study to address these issues.
Although the possibility of a large NEO impact with Earth is remote, conducting surveys of NEOs and studying means to mitigate collisions with them can best be viewed as a form of insurance. It seems prudent to expend some resources to prepare to counter this collision threat. Most homeowners, for example, carry fire insurance, although no one expects her or his house to burn down anytime soon. The distinction between insurance for the NEO collision hazard and other “natural” hazards, such as earthquakes and hurricanes, is that the possibility of detecting and preventing most serious collisions now exists. In the case of earthquakes, for example, despite extensive efforts, primarily in China, Japan, and the United States, neither the epoch nor the severity of an earthquake can yet be reliably predicted. Governments do nonetheless fund the analog of an insurance policy through studies of this hazard and through the design and construction of earthquake-resistant structures and in development of plans for response and recovery. The goal is to reduce both the number of fatalities and the damage to property from earthquakes. According to figures from the NRC (2006) report Improved Seismic Monitoring—ImprovedDecision-Making: Assessing the Value of Reduced Uncertainty, the United States alone now spends well in excess of $100 million annually on this suite of earthquake-related efforts. The annual death rate in the United States from earthquakes, averaged over the past two centuries for which data are available, is approximately 20 per year, with 75 percent of that figure attributed to the 1906 San Francisco Earthquake, mostly from related fires. For Japan, both the expenditure and the fatality figures are far larger. China and other parts of Asia have also suffered massive casualties from earthquakes. The September 2009 earthquakes that caused loss of life in Indonesia, Samoa, and American Samoa, and the devastating January 2010 earthquake in Haiti and February 2010 earthquake in Chile, highlight this ongoing threat to human life.
Given the low risk over a period of, say, a decade (see Chapter 2), how much should the United States invest in NEO insurance? This question requires a political, not a scientific, answer. Yet the question bears on the committee’s charge. The committee was asked to recommend the optimal approach for each of the tasks, with the definition of “optimal” left to the committee. A unique characteristic of the “NEO research premiums,” which distinguishes them from the usual types of insurance, is that the premiums would be directed entirely toward the prevention of the catastrophe.
The committee interprets “deflection” to mean “orbit change.”