NASA SHOULD LEAD MORE FOCUSED PROGRAM TO REDUCE THREAT FROM HAZARDOUS ASTEROIDS (press release) February 4, 2003 NASA should be assigned to lead a new research program to better determine the population and physical diversity of near-Earth objects that may collide with our planet, down to a size of 200 meters, according to the final report of a workshop on the scientific requirements for the mitigation of hazardous comets and asteroids. The workshop's report also recommends that the U.S. Department of Defense (DoD) work to more rapidly communicate surveillance data on natural airbursts of smaller rocky bodies, and it concludes that governmental policy makers must "formulate a chain of responsibility" to be better prepared in the event that a threat to Earth becomes known. "As our discussions proceeded, it became clear that the prime impediment to further advances in this field is the lack of assigned responsibility to any national or international governmental organization," said planetary scientist Michael Belton, organizer of the September 2002 workshop. "Since it is part of NASA's newly stated mission to `understand and protect our home planet,' it seems obvious that this responsibility should reside in NASA." Belton presented the findings of the workshop today in Washington, DC, to officials at NASA, the National Science Foundation, and the Office of Management and Budget, and the report was delivered to the U.S. Congress. About 2,225 near-Earth objects (NEOs) have been detected, primarily by ground-based optical searches, in the size range between 10 meters and 30 kilometers, out of a total estimated population of about one million; some information about the physical size and composition of these NEOs is available for only 300 objects. The total number of objects a kilometer in diameter or larger, a size that could cause global catastrophe upon Earth impact, is now estimated to range between 900 and 1,230. The NASA-led Spaceguard Survey has a congressional mandate to detect 90% of these kilometer-sized objects by 2008, and it is making "excellent progress" on this goal, the report says. However, a full survey of objects that could cause significant damage on Earth should reach down to NEOs at least as small as 200 meters, the report says, which should be within the capability of proposed ground-based facilities such as the Large Synoptic Survey Telescope and the PanStarrs telescope system. Ground-based radar systems will remain a "critical contributor" to obtaining the most accurate possible data on the orbits of many hazardous objects, the report says. The workshop report discusses a preliminary roadmap based on five themes: more complete and accurate surveys of the orbits of potentially hazardous objects; improved public education about the risk; characterizing the physical properties of a range of asteroids and comets; more extensive laboratory research; and initial physical experiments toward a realistic plan to intercept and divert a future incoming object. In order to keep maximum annual expenses on the order of a typical spacecraft mission (approximately $300 million), the report estimates that it would take about 25 years to accomplish this roadmap. The Final Report of the NASA Workshop on Scientific Requirements for Mitigation of Hazardous Comets and Asteroids, held in Arlington, VA, from September 3-6, 2002, is available on the Internet at: http://www.noao.edu/meetings/mitigation/report.html The workshop was attended by 77 scientists from the United States, Europe and Japan. It was co-sponsored by Ball Aerospace, Science Applications International Corp., Lockheed Martin Corp., the National Optical Astronomy Observatory and the University of Maryland.
NASA SHOULD LEAD ASTEROID DEFENSE (news story) From National Geographic News, 4 February 2003 Earth has a history of being struck by asteroids, sometimes with devastating effects such as tsunamis, firestorms, and even large-scale extinction of life. Yet no one knows for sure how many large asteroids are out there and if-or when-one might be headed for us. Now a group of experts has recommended a strategy to prepare a planetary defense. The biggest obstacle towards creating a plan to defend Earth against asteroid impacts is that no national or international organization has been tasked with the job, says an international group of scientists, engineers, and military experts who gathered to assess the danger. The group recommends that NASA should get the job. The Workshop on Scientific Requirements for Mitigation of Hazardous Comets and Asteroids gathered 77 experts from the United States, Europe, and Japan. It released its final report this week. "NASA should be assigned to lead a new research program to better determine the population and physical diversity of near-Earth objects that may collide with our planet, down to a size of 200 meters (200 yards)," according to a statement released by the workshop. The workshop's report also recommended that the U.S. Department of Defense (DoD) work to more rapidly communicate surveillance data on natural airbursts of smaller rocky bodies, and it concludes that governmental policy makers must "formulate a chain of responsibility" to be better prepared in the event that a threat to Earth becomes known. "As our discussions proceeded, it became clear that the prime impediment to further advances in this field is the lack of assigned responsibility to any national or international governmental organization," said planetary scientist Michael Belton, organizer of the September 2002 workshop. "Since it is part of NASA's newly stated mission to 'understand and protect our home planet,' it seems obvious that this responsibility should reside in NASA." Belton presented the findings of the workshop this week in Washington, D.C., to officials at NASA, the National Science Foundation, and the Office of Management and Budget, and the report was delivered to the U.S. Congress. About 2,225 near-Earth objects (NEOs) have been detected, primarily by ground-based optical searches, in the size range between 10 meters (11 yards) and 30 kilometers (19 miles), out of a total of about one million. But some information about the physical size and composition of these NEOs is available for only about 300 objects. The total number of objects a kilometer in diameter or larger, a size that could cause global catastrophe upon Earth impact, is now estimated to range between 900 and 1,230, according to the workshop. The NASA-led Spaceguard Survey has a congressional mandate to detect 90 percent of these kilometer-sized (thousand-yard) objects by 2008, and it is making "excellent progress" on this goal, the report said. However, a full survey of objects that could cause significant damage on Earth should reach down to NEOs at least as small as 200 meters (220 yards), the report said, which should be within the capability of proposed ground-based facilities such as the Large Synoptic Survey Telescope and the PanStarrs telescope system. Ground-based radar systems will remain a "critical contributor" to obtaining the most accurate possible data on the orbits of many hazardous objects, the report said. The workshop report discusses a preliminary "roadmap" based on five themes: more complete and accurate surveys of the orbits of potentially hazardous objects; improved public education about the risk; characterizing the physical properties of a range of asteroids and comets; more extensive laboratory research; and initial physical experiments toward a realistic plan to intercept and divert a future incoming object. In order to keep maximum annual expenses on the order of a typical spacecraft mission (approximately U.S. $300 million), the report estimates that it would take about 25 years to accomplish this roadmap.
FINAL REPORT: NASA WORKSHOP ON SCIENTIFIC REQUIREMENTS FOR MITIGATION OF HAZARDOUS COMETS AND ASTEROIDS (executive sumary) Workshop held in Arlington, VA, September 3-6, 2002 1. EXECUTIVE SUMMARY AND RECOMMENDATIONS Purpose of the workshop and primary conclusions: The "Workshop on Scientific Requirements for Mitigation of Hazardous Comets and Asteroids," supported by the NASA's Office of Space Science, was held on September 3 - 6, 2002, at the Hyatt Hotel in Arlington, VA. Seventy-seven scientists, engineers and military experts from the United States, Europe, and Japan participated. Its purpose was to consider the scientific requirements for avoidance and mitigation of hazards to the Earth due to asteroids and comets, i.e., what should be done to ensure that an adequate base of scientific knowledge is created that will allow efficient development of a reliable, but as yet undefined, collision mitigation system when needed in the future. It became clear that the prime impediment to further advances in this field is the lack of any assigned responsibility to any national or international governmental organization to prepare for a disruptive collision and the absence of any authority to act in preparation for some future collision mitigation attempt. Eighteen major conclusions (listed below) were formulated that provided the basis for five recommendations. In brief, these are: That NASA be assigned the responsibility to advance this field, That a new and adequately funded program be instituted at NASA to create, through space missions and allied research, the specialized knowledge base needed to respond to a future threat of a collision from an asteroid or comet nucleus, That the Spaceguard survey be extended to cover the hazardous part of the population of possible impactors down to 200 m in size, That the DoD more rapidly communicate surveillance data on natural airbursts, That governmental policy makers formulate a chain of responsibility for action in the event a threat to the Earth becomes known. A record of some of the workshop presentations can be found in a volume of extended abstracts on the web at: www.noao.edu/meetings/mitigation/eav.html. Other invited papers will be published by Cambridge University Press as a book entitled "Mitigation of Hazardous Impacts due to Asteroids and Comets," in the spring of 2003. What was discussed: All aspects of near-Earth objects were discussed. These included the completeness of our knowledge about the population of potential impactors, their physical and compositional characteristics, the properties of surveys that need to be done to find hazardous objects smaller than 1 km in size, our theoretical understanding of impact phenomena, new laboratory results on the impact process, the need for space missions of specific types, education of the public, public responsibility for dealing with the threat, and the possible roles of NASA, the military, and other agencies in mitigating the threat. Brief assessment of status and needs: About 2,225 near-Earth objects are now known in the 10m to 30km size range out of a total population of about a million. Physical information exists only for a small number (~300) of these. It is estimated that there are roughly 25,000 are larger than 150m in size (above which the potential exists for easy penetration of the Earth's protective atmosphere) but it is estimated that only ~250 of these are potentially hazardous. The number of objects larger than 1 km (i.e., objects capable of global scale catastrophe) is now estimated to lie between 900 and 1230 and about 55% of these have been found - none on Earth intersecting trajectories. Without continuing improvements to existing survey equipment it is expected that ~70% will have been found by 2008. Extension of the Spaceguard survey may be needed to achieve its goal. To find a significant fraction of potentially hazardous objects between 100m and 1km in a reasonable time will require advanced telescopic capabilities (LSST, PanStarrs). Extensive follow-up astrometric observations including radar data will also be needed to confidently identify hazardous impactors with enough lead-time (decades) to allow effective mitigation. New space and telescopic observations together with modeling indicate high internal porosity for many near-Earth objects and have resulted in changing views as to the nature of the surface processes on asteroids. Physical and compositional knowledge of the surface layers and interiors of near-Earth objects, given their diversity, is judged inadequate for mitigation purposes. Extensive observational and experimental studies from spacecraft, and Earth based telescopic systems, are required. Similarly laboratory and theoretical work is needed to clarify how porosity at the surface or in the interior of an object affects the outcome of a rapid application of large amounts of energy. Modeling suggests that deep layers of porous surface materials may have a dramatic effect on mitigation using high-energy explosives so that with previous estimates of requirements may have to be possibly increased by factors of 100 or more. Substantial investment and time will be required to accomplish an adequate level of physical and compositional knowledge. A roadmap for future advances: A strawman roadmap suggests that $5-6B over 25yr (to keep total annual expenditures to <$300M/yr) involving a number of government agencies will be required. This roadmap also includes resources for in-space interaction experiments so that the process of learning how to apply possible mitigation techniques, and the rapid identification of the most effective techniques, can begin. Major conclusions: On the hazardous population - A future collision of an asteroid or cometary nucleus with the Earth with catastrophic effects is inevitable unless technology is developed to modify the orbit of such bodies. The most likely objects to collide with the Earth with catastrophic effects are 100 m or more in size and have a significant probability (20%) of colliding with the Earth over times of human interest (~100yr). Excellent progress has been made in satisfying the congressional mandate charged to NASA to find 90% of near-Earth objects with H<18 (size greater than 1 km) by 2008. However, models indicate that completion by 2008 will require that technical improvements to the current discovery systems be made. On the organization needed to respond to a threat - There exists no government agency or international organization with the assignment or acceptance of responsibility for averting the threat of an impending collision. Once an object is verified to be on an Earth-threatening trajectory, there is no identified organization responsible for the timely reporting of these events to the public or other nations The NASA charter includes the goal of protecting our home planet, which is relevant to the mitigation problem. The priorities of the technical and scientific objectives of space missions designed to acquire a relevant basis of knowledge for mitigation purposes may be distinct from those in other high priority space exploration programs which address the same class of targets (small planetary bodies) and that are already being pursued by NASA and other foreign space agencies. The costs incurred by the above program of space and associated Earth-based research will be substantial, but possibly could eventually be offset by profitable activities in the low-gravity, resource-rich environment of asteroids and cometary nuclei. An estimate of the time necessary to acquire this basis of knowledge is measured in decades. The threat of catastrophic collisions with the Earth is global and any and all nations may be affected. There is strong international interest in understanding the nature of this threat. On what is required to respond to a threat - The development of a relevant and adequate knowledge basis for future attempts to reliably mitigate an impending collision of an object greater than 100 m in size will require scientific proof of the efficacy of a wide range of proposed techniques in the space environment, including ways to measure relevant physical and compositional properties. A series of space missions is required in order to acquire a relevant and adequate basis of knowledge on which to base the future development of a reliable collision mitigation system. A multifaceted program of Earth-based theoretical, experimental, observational, and interpretive research is necessary to support, complement, guide, and extend a program of space missions for mitigation purposes. Relatively low-cost Earth-based surveys for NEOs are now technically feasible down to a size limit of about 200 m. Committees of the National Research Council of the National Academy of Sciences have recommended the construction of a large-aperture synoptic survey telescope (LSST) that is capable of detecting 90% of near-Earth objects above the 200 m size limit within approximately a decade. On concerns with current activities - Department of Defense space surveillance programs regularly observe upper atmosphere airbursts with the release of 1 kT of energy and above caused by objects entering the Earth's atmosphere from space with typical sizes near 10 m. The public and other nations with nuclear capability outside the U.S. may not be aware of this continuing flux of extraterrestrial objects and their effects in the Earth's upper atmosphere. Recommendations: Based on the above conclusions, the members of the workshop's scientific and local organizing committees formulated the following recommendations that, when implemented, will lead to the acquisition of a relevant body of scientific knowledge on which a practical and reliable collision mitigation system could be developed at some time in the future. Recommendation 1. That the National Aeronautics and Space Administration be assigned the responsibility to acquire relevant scientific knowledge on the compositional and physical properties of the diverse population of hazardous objects that may threaten the Earth and on which the future development of a reliable collision mitigation system could be based. In undertaking this responsibility, the interests and cooperative support of the international community should be welcomed. Recommendation 2. That a new and appropriately funded program be instituted at the National Aeronautics and Space Administration, consistent with its mission to "Understand and protect our home planet," to create an adequate basis of scientific knowledge through space missions and supporting Earth-based research on which future attempts to reliably mitigate impending collisions of hazardous objects with the Earth can be founded. Recommendation 3. That the congressionally mandated survey presently being pursued by the National Aeronautics and Space Administration to catalog near-Earth objects brighter than H~18 (~ 1 km in size), be extended to include 90% of hazardous near-Earth objects down to a size range of 200 m over the next decade. Recommendation 4. That the Department of Defense increase the speed with which it makes information about natural airburst phenomena available to the public and other nations to prevent possible misinterpretations of these small, frequent events. Recommendation 5. That government and international policy makers act now to formulate and publish an agreed uponto chain of responsibility for action in the event that an Earth-threatening object is discovered. FULL REPORT at http://www.noao.edu/meetings/mitigation/workshop_report_final.html |
