In 2016, NASA took on a new responsibility: defending our planet from devastating impacts by asteroids and comets that approach the Earth, or near-Earth objects. That event, which followed the prominent Chelyabinsk meteor explosion in 2013, reflected a growing interest in, and concern about, the threat of celestial impacts. In ancient times, the solar system's small bodies-asteroids and comets-were sometimes seen as ill omens and warnings from the gods. In modern times, they have come to be seen as the solar system's rubble, leftovers from its formation, but were still largely ignored until the late 20th century. Increasingly, they have been seen by scientists as objects worthy of study, by the general public and the U.S. government as potential threats to be mitigated, and by space advocates as future resources. This book tells the fascinating story of these reinterpretations and NASA's role in them.

An insider's look at the science of near-Earth comets and asteroids Of all the natural disasters that could befall us, only an Earth impact by a large comet or asteroid has the potential to end civilization in a single blow. Yet these near-Earth objects also offer tantalizing clues to our solar system's origins, and someday could even serve as stepping-stones for space exploration. In this book, Donald Yeomans introduces readers to the science of near-Earth objects—its history, applications, and ongoing quest to find near-Earth objects before they find us. In its course around the sun, the Earth passes through a veritable shooting gallery of millions of nearby comets and asteroids. One such asteroid is thought to have plunged into our planet sixty-five million years ago, triggering a global catastrophe that killed off the dinosaurs. Yeomans provides an up-to-date and accessible guide for understanding the threats posed by near-Earth objects, and also explains how early collisions with them delivered the ingredients that made life on Earth possible. He shows how later impacts spurred evolution, allowing only the most adaptable species to thrive—in fact, we humans may owe our very existence to objects that struck our planet. Yeomans takes readers behind the scenes of today’s efforts to find, track, and study near-Earth objects. He shows how the same comets and asteroids most likely to collide with us could also be mined for precious natural resources like water and oxygen, and used as watering holes and fueling stations for expeditions to Mars and the outermost reaches of our solar system.

Comets and asteroids are in some sense the fossils of the solar system. They have avoided most of the drastic physical processing that shaped the planets and thus represent more closely the properties of the primordial solar nebula. What processing has taken place is itself of interest in decoding the history of our solar neighborhood. Near-Earth objects are also of interest because one or more large ones have been blamed for the rare but devastating events that caused mass extinctions of species on our planet, as attested by recent excitement over the impending passage of asteroid 1997 XF11. The comets and asteroids whose orbits bring them close to Earth are clearly the most accessible to detailed investigation, both from the ground and from spacecraft. When nature kindly delivers the occasional asteroid to the surface of Earth as a meteorite, we can scrutinize it closely in the laboratory; a great deal of information about primordial chemical composition and primitive processes has been gleaned from such objects. This report reviews the current state of research on near-Earth objects and considers future directions. Attention is paid to the important interplay between ground-based investigations and spaceborne observation or sample collection and return. This is particularly timely since one U.S. spacecraft is already on its way to rendezvous with a near-Earth object, and two others plus a Japanese mission are being readied for launch. In addition to scientific issues, the report considers technologies that would enable further advances in capability and points out the possibilities for including near-Earth objects in any future expansion of human exploration beyond low Earth orbit.

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.

Presents a realistic, workable plan for defusing a potentially lethal threat from a rogue asteroid or comet. The explosion of a large meteor over Chelyabinsk, Siberia, in February 2013 is just the latest reminder that planet Earth is vulnerable to damaging and potentially catastrophic collisions with space debris of various kinds. In this informative and forward-looking book, veteran aerospace writer William E. Burrows explains what we can do in the future to avoid far more serious impacts from "Near-Earth Objects" (NEOs), as they are called in the planetary defense community. The good news is that humanity is now equipped with the advanced technology necessary to devise a long-term strategy to protect the planet. Burrows outlines the following key features of an effective planetary defense strategy- * A powerful space surveillance system capable of spotting a serious threat from space at least a year in advance * A space craft "nudge" that would throw a collision-course asteroid off target long before it poses the threat of imminent impact * A weapons system to be used as a last-ditch method to blast an NEO should all else fail. The author notes the many benefits for world stability and increasing international cooperation resulting from a united worldwide effort to protect the planet. Combining realism with an optimistic can-do attitude, Burrows shows that humanity is capable of overcoming a potentially calamitous situation.

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.

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.

"To commemorate the 50th anniversary of the first successful planetary mission, Mariner 2 sent to Venus in 1962, the NASA History Program Office, the Division of Space History at the National Air and Space Museum, NASA's Science Mission Directorate, and the Jet Propulsion Laboratory organized a symposium. "Solar System Exploration @ 50" was held in Washington, D.C., on 25-26 October 2012. The purpose of this symposium was to consider, over the more than 50-year history of the Space Age, what we have learned about the other bodies of the solar system and the processes by which we have learned it. Symposium organizers asked authors to address broad topics relating to the history of solar system exploration such as various flight projects, the development of space science disciplines, the relationship between robotic exploration and human spaceflight, the development of instruments and methodologies for scientific exploration, as well as the development of theories about planetary science, solar system origins and implications for other worlds. The papers in this volume provide a richly textured picture of important developments - and some colorful characters - in a half century of solar system exploration. A comprehensive history of the first 50 years of solar system exploration would fill many volumes. What readers will find in this volume is a collection of interesting stories about money, politics, human resources, commitment, competition and cooperation, and the "faster, better, cheaper" era of solar system exploration"--

"More than forty chapters detail our current astronomical, compositional, geological, and geophysical knowledge of asteroids, as well as their unique physical processes and interrelationships with comets and meteorites"--Provided by publisher.

This book documents highlights of NASA's interactions with outside scientific advisors over the agency's full lifetime and draws lessons from that history for research managers, decision makers, and scientists.The book is divided into three parts--the first two being focused on history and the third on synthesis and analysis. Part 1 briefly examines early forerunner activities at NACA and in the decade leading up to NASA's formation, and it then considers NASA's use of outside advice during its first three decades. Part 2 picks up the story in 1988 and follows it up to 2016. Part 3 examines a sampling of case studies, discusses recurring characteristics of notably successful advisory activities, and provides a glimpse at what past experience might imply for the future of scientific advice at NASA. The last two chapters provide big-picture summaries of themes that have emerged from earlier discussions.