Near-Earth Object Surveys and Hazard Mitigation Strategies Interim Report (2009) / Chapter Skim
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Interim Report on Near-Earth Object Surveys and Hazard Mitigation Strategies
Interim Report on Near-Earth Object Surveys and Hazard Mitigation Strategies
Pages 1-18
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From page 1... ...
In part because of this interrelationship, and because the interim report does not address mitigation issues, the committee has deferred proposing an optimum approach to the survey and detection problem until its final report. The final report will contain findings and recommendations for survey and detection, characterization, and mitigation of near-Earth objects based on an integrated assessment of the problem.
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government spends a relatively small amount of money funding a search and survey program to discover and track near-Earth objects, and virtually no money on studying methods of mitigating the hazards posed by such objects.3 Although Congress has mandated that NASA conduct this survey program and has established goals for the program, neither Congress nor the administration has sought to fund it with new appropriations. As a result, NASA has supported this activity by taking funds from other programs, while still leaving a substantial gap between the goals established by Congress and the funds needed to achieve them.
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From page 3... ...
The NASA Multi-year Authorization Act of 1990 that was passed by Congress directed NASA to study both the discovery of potentially threatening asteroids and the technology for possible mitigation if an object on a collision course with Earth were to be found. The studies outlined in this legislation were prompted by recommendations to Congress in 1989 by the American Institute of Aeronautics and Astronautics shortly after asteroid 1989 FC passed close to Earth.
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From page 4... ...
, the potentially threatening comets and asteroids larger than 1 kilometer in diameter." The 1995 NASA NEO Survey Workgroup Report Asteroid and Comet Impact Hazards was NASA's response to Congress.6 The plan laid out by the workshop, if effective, would lead to discovery of 60 to 70 percent of NEOs larger than 1-kilometer diameter within one decade (i.e., by 2006)
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From page 5... ...
The search efforts were accompanied by study and evaluation. In 2003 a major scientific study of the issue concluded that with the goal of discovering 90 percent of 1-kilometer diameter or larger objects almost attained, and with new survey and discovery equipment becoming available, the goal should be revised.7 This proposed change coincided with an increasing understanding of the potential threat posed by smaller objects.
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PAST NEO DISCOVERY EFFORTS The survey/discovery effort for NEOs has proceeded through several phases. In recent years several previous NEO survey programs shut down or are being phased out primarily because more capable surveys have come online.
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PRESENT NEO DISCOVERY EFFORTS In 2005, five programs were operational: Catalina Sky Survey (CSS) ; the Lincoln Near-Earth Asteroid Research (LINEAR)
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From page 8... ...
Existing large telescopes have very small fields of view and are therefore unsuitable for achieving the survey goal. Finding: The current near-Earth object surveys cannot meet the goals of the 2005 NASA Authorization Act directing NASA to discover 90 percent of all near-Earth objects 140 meters in diameter or greater by 2020.
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From page 9... ...
, it would allow detection of NEOs using the same data acquired for other scientific purposes, such as studying cosmology or stellar variability. The efficiency of LSST in detecting NEOs could be boosted if it were solely dedicated to this purpose.
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The MPC in general has no problems with these processes at the observatories, although as advanced telescopes are developed, the observatories will face additional challenges in handling increasingly large amounts of data. As long as adequate funding is provided, the MPC appears to be capable of handling all of the observations generated, even beyond the congressionally mandated survey.
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From page 11... ...
Currently one of the most effective methods involves radar observations when the NEO is within range for detailed study. Two radar telescopes are used in part to characterize and track NEOs⎯at the Arecibo Observatory in Puerto Rico and at the Goldstone Deep Space Communications Complex (GDSCC; referred to as the Goldstone Observatory)
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FIGURE 2 Arecibo radar images of 2-kilometer-diameter asteroid 1992 UY4 made from four days' observations in August 2005. Radar images are unusual in that the coordinates are not spatial ones on the plane of the sky.
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OPTIONS FOR MEETING THE 140-METER-DIAMETER OBJECT DISCOVERY GOAL The 2007 NASA analysis of alternatives report15 outlined several alternatives for achieving the discovery goals established in the 2005 NASA Authorization Act. Figure 3 indicates how these alternatives would meet or approach the congressionally mandated goals.
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From page 14... ...
Several smaller projects, such as the Beijing Schmidt CCD Asteroid Program (no longer operational) and the Asiago DLR Asteroid Survey (an ongoing joint venture between the German Aerospace Agency's [DLR's]
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From page 15... ...
NEOSSat will expand overall knowledge of NEOs, monitor them for cometary activity, perform follow-up tracking of newly discovered targets, aid in the development of asteroid search and tracking algorithms for space-based sensors, and explore the synergies between ground- and space-based facilities involved in NEO discovery and characterization. Finding: The United States is the only country that currently has an operating survey/detection program for discovering near-Earth objects; Canada and Germany are both building spacecraft that may contribute to the discovery of near-Earth objects.
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From page 16... ...
Because asteroid impacts can occur with warning periods ranging from hours to many centuries, and dangerous impacting objects can range from a few tens of meters to many kilometers in diameter, and can be composed of ice, rock, or metallic iron, it is unlikely that any one mitigation strategy will offer a universal defense. Instead, each plausible strategy (and others yet to be conceived)
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From page 17... ...
If the threat of NEOs and solutions to deal with that threat are to be further explored, additional resources will be required, such as for completion of dedicated telescopes and increased funding for existing key facilities and research and analysis programs.
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