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Defending Planet Earth: Near-Earth-Object Surveys and Hazard Mitigation Strategies
$2 million to support research on a range of issues related to NEO hazards, including but not necessarily limited to (see Chapter 6) the study of sky distribution of NEOs and the development of warning-time statistics; concept studies of mitigation missions; studies of bursts in the atmosphere of incoming objects greater than a few meters in diameter; laboratory studies of impacts at speeds up to the highest feasible to obtain; and leadership and organizational planning, both nationally and internationally.
The $10-million funding level would not allow on any time scale the completion of the mandated survey to discover 90 percent of near-Earth objects of 140 meters in diameter or greater. Also lost would be any possibility for mounting spacecraft missions—for example, to test active mitigation techniques in situ.
(A caveat: The funds designated above to support radar observations are for these observations alone; were the maintenance and operations of the radar-telescope sites not supported as at present, there would be a very large shortfall for both sites: about $10 million annually for the Arecibo Observatory and likely a larger figure for the Goldstone Observatory.)
$50-million level. At a $50-million annual appropriations level, in addition to the tasks listed above, the committee notes that the remaining $40 million could be used for the following:
Support of a ground-based facility, as discussed in Chapter 3, to enable the completion of the congressionally mandated survey to detect 90 percent of near-Earth objects of 140 meters in diameter or greater by the delayed date of 2030.
The $50-million funding level would likely not be sufficient for the United States alone to conduct space telescope missions that might be able to carry through a more complete survey faster. In addition, this funding level is insufficient for the development and testing of mitigation techniques in situ. However, such missions might be feasible to undertake if conducted internationally, either in cooperation with traditional space partners or as part of an international entity created to work on the NEO hazards issue. Accommodating both the advanced survey and a mitigation mission at this funding level is very unlikely to be feasible, except on a time scale extended by decades.
$250-million level. At a $250-million annual budget level, a robust NEO program could be undertaken unilaterally by the United States. For this program, in addition to the research program a more robust survey program could be undertaken that would include redundancy by means of some combination of ground-and space-based approaches. This level of funding would also enable a space mission similar to the European Space Agency’s (ESA’s) proposed Don Quijote spacecraft, either alone, or preferably as part of an international collaboration. This space mission would test in situ instrumentation for detailed characterization, as well as impact technique(s) for changing the orbit of a threatening object, albeit on only one NEO. The target could be chosen from among those fairly well characterized by ground observations so as to check these results with those determined by means of the in situ instruments.
The committee assumed constant annual funding at each of the three levels. For the highest level the annual funding would likely need to vary substantially as is common for spacecraft programs. Desirable variations of annual funding over time would likely be fractionally lower for the second level, and even lower for the first level.
How long should funding continue? The committee deems it of the highest priority to monitor the skies continually for threatening NEOs; therefore, funding stability is important, particularly for the lowest level. The second level, if implemented, would likely be needed at its full level for about 4 years in order to contribute to the completion of the mandated survey. The operations and maintenance of such instruments beyond this survey has not been investigated by the committee. However, were the Large Synoptic Survey Telescope to continue operating at its projected costs, this second-level budget could be reduced. The additional funding provided in the third and highest level would probably be needed only through the completion of the major part of a Don Quijote-type mission, under a decade in total, and could be decreased gradually but substantially thereafter.
Finding: A $10-million annual level of funding would be sufficient for continuing existing surveys, maintaining the radar capability at the Arecibo and Goldstone Observatories, and supporting a modest levelof research on the hazards posed by near-Earth objects. This level would not allow the achievement of the