In 1993, the U.S. Department of Defense declassified information dealing with frequent explosions in the upper atmosphere caused by meteoric impact. It is estimated that impacts have occurred of a magnitude equivalent to the atomic bomb detonated at Hiroshima. Not all such space voyagers meet their end in the atmosphere, however; huge craters attest to the bombardment of earth over millions of years, and a major impact may have resulted in the extinction of dinosaurs. An impact in Siberia near the beginning of this century proves that such events are not confined to geologic time. Hazards Due to Comets and Asteroids marks a significant step in the attempt to come to grips with the threats posed by such phenomena. It brings together more than one hundred scientists from around the world, who draw on observational and theoretical research to focus on the technical problems related to all aspects of dealing with these hazards: searching for and identifying hazardous comets and asteroids; describing their statistics and characteristics; intercepting and altering the orbits of dangerous objects; and applying existent technologies—rocket boosters, rendezvous and soft-landing techniques, instrumentation—to such missions. The book considers defensive options for diverting or disrupting an approaching body, including solar sails, kinetic-energy impacts, nuclear explosives, robotic mass drivers, and various propulsion systems. A cataclysmic impact posing a threat to life on Earth is a possibility that tomorrow's technology is capable of averting. This book examines in depth the reality of the threat and proposes practical measures that can be initiated now should we ever need to deal with it.

Leading specialists in various disciplines were first invited to a multidisciplinary workshop funded by ICSU on the topic to gain a better appreciation and perspective on the subject of comet/asteroid impacts as viewed by different disciplines. This volume provides a necessary link between various disciplines and comet/asteroid impacts.

The United States spends approximately $4 million each year searching for near-Earth objects (NEOs). The objective is to detect those that may collide with Earth. The majority of this funding supports the operation of several observatories that scan the sky searching for NEOs. This, however, is insufficient in detecting the majority of NEOs that may present a tangible threat to humanity. A significantly smaller amount of funding supports ways to protect the Earth from such a potential collision or "mitigation." In 2005, a Congressional mandate called for NASA to detect 90 percent of NEOs with diameters of 140 meters of greater by 2020. Defending Planet Earth: Near-Earth Object Surveys and Hazard Mitigation Strategies identifies the need for detection of objects as small as 30 to 50 meters as these can be highly destructive. The book explores four main types of mitigation including civil defense, "slow push" or "pull" methods, kinetic impactors and nuclear explosions. It also asserts that responding effectively to hazards posed by NEOs requires national and international cooperation. Defending Planet Earth: Near-Earth Object Surveys and Hazard Mitigation Strategies is a useful guide for scientists, astronomers, policy makers and engineers.

This volume is a compilation of the research presented at the International Asteroid Day workshop which was celebrated at Barcelona on June 30th, 2015. The proceedings discuss the beginning of a new era in the study and exploration of the solar system’s minor bodies. International Asteroid Day commemorates the Tunguska event of June 30th, 1908. The workshop’s goal was to promote the importance of dealing proactively with impact hazards from space. Multidisciplinary experts contributed to this discussion by describing the nature of comets and asteroids along with their offspring, meteoroids. New missions to return material samples of asteroids back to Earth such as Osiris-REx and Hayabusa 2, as well as projects like AIM and DART which will test impact deflection techniques for Potentially Hazardous Asteroids encounters were also covered. The proceedings include both an outreach level to popularize impact hazards and a scientific character which covers the latest knowledge on these topics, as well as offering proposals of promising new techniques that will help gain new insights of the properties of these challenging bodies by studying meteoroids and meteorites. Asteroids, comets, meteoroids and meteorites are introduced with descriptions of their nature, origin, and solar system pathways.

It is known that large asteroids and comets can collide with the Earth with severe consequences. Although the chances of a collision in a person's lifetime are small, collisions are a random process and could occur at any time. This book collects the latest thoughts and ideas of scientists concerned with mitigating the threat of hazardous asteroids and comets. It reviews current knowledge of the population of potential colliders, including their numbers, locations, orbits, and how warning times might be improved. The structural properties and composition of their interiors and surfaces are reviewed, and their orbital response to the application of pulses of energy is discussed. Difficulties of operating in space near, or on the surface of, very low mass objects are examined. The book concludes with a discussion of the problems faced in communicating the nature of the impact hazard to the public.

Federal patronage of science was never contemplated by the framers of the Constitution, but they did seek to “promote the Progress of Science and useful Art” by granting inventors patent rights. However, direct subvention to scientists and scientific organizations was not considered appropriate activity of the central government. In the 19th Century, American science was funded almost entirely through private investors. Since WWII, however, the federal government has become the primary patron of American science. From the race-to-space in the 1950s to current furor over global warming, Bennett traces the subtle and not-so-subtle ways in which government has co-opted scientific research and reinforced a culture in which challengers to proscribed wisdom are frozen out. Citing original documents and media reports, Bennett offers a compelling, entertaining, and thought-provoking perspective on political influence on scientific research and its implications for a democratic society. "During the Nineteenth Century, almost entirely on private funding, American science grew from practically nothing to world class. Now, however, over fifty percent of American science is funded by the federal government. Dr. Bennett traces the path, "crisis" after "crisis," by which American science became practically an arm of the federal government. His tale is a cautionary one, warning against future "crisis mongers" who would extend the government's already majority control of American science even further. His warning is a timely one, and it should be heeded." Joseph P. Martino, author of Science Funding: Politics and Porkbarrel "Bennett's latest book offers a challenging interpretation of the rise of the American federal science establishment since World War II. Focusing primarily on the growth of the space program, Bennett argues that crisis, real or imagined, is the source of state power and state funding for science. The Doomsday Lobby offers what no doubt will be viewed as a controversial contribution to the history of American science policy, and more broadly to an understanding of the role of the state in society." James D. Savage, Professor of Politics, University of Virginia, and author of Funding Science in America

"Comprises articles stemming from the March 2013 international conference at London's Natural History Museum. Researchers across geological, geophysical, and biological disciplines present key results from research concerning the causes of mass extinction events"--

An asteroid or comet will inevitably strike the Earth some day, and potentially cause great destruction. This volume considers hazards due to collisions with cosmic objects, particularly in light of recent investigations of impacts by the authors. Each chapter, written by an expert, contains an overview of an aspect and new findings in the field. Coverage describes and numerically estimates the main hazardous effects.

Disk contains: HAZARDS version 5.5, designed to predict asteroid or comet impacts with the Earth.

The impact of extraterrestrial material on Earth can lead to effects traceable in both the geological and biological record. This study describes meteorite flux with time, covering small and large bodies capable of producing craters. The effects of impacts on the environment is also covered focusing specifically on the Cretaceous-Tertiary mass extinction event.