Near-Earth Objects

Near-Earth Objects: Finding Them Before They Find Us

DONALD K. YEOMANS
Copyright Date: 2013
Pages: 200
https://www.jstor.org/stable/j.ctt1r2fck
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  • Book Info
    Near-Earth Objects
    Book Description:

    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.

    eISBN: 978-1-4008-4463-0
    Subjects: Astronomy, General Science

Table of Contents

  1. Front Matter
    (pp. i-iv)
  2. Table of Contents
    (pp. v-vi)
  3. ILLUSTRATIONS
    (pp. vii-x)
  4. PREFACE
    (pp. xi-xii)
  5. ACKNOWLEDGMENTS
    (pp. xiii-xvi)
  6. CHAPTER 1 Earth’s Closest Neighbors
    (pp. 1-14)

    Let me introduce Michelle Knapp of Peekskill, New York, and her 1980 Chevy Malibu sedan. On a rainy Friday night, October 9, 1992, just before 8:00 PM, Michelle, an eighteen-year-old high school senior, heard a loud crash in her driveway and raced outside to discover the rear end of her automobile had been completely destroyed by a footballsized rock. The twenty-seven-pound projectile had punched completely through the trunk, just missing the gas tank.

    As unlikely as it sounds, a fragment of a near-Earth asteroid that had collided with Earth destroyed Michelle’s car. The fiery trail of the initial, Volkswagen-sized, near-Earth...

  7. CHAPTER 2 The Solar System’s Origin: The Classical View
    (pp. 15-28)

    On September 5, 1977, the Voyager I spacecraft was launched from Cape Canaveral, Florida, and began its audacious journey of planetary exploration. Its suite of scientific instruments included an imaging camera and devices to measure the atmospheres and environments of the giant gas planets Jupiter and Saturn. The spacecraft carried a goldanodized aluminum record with an engraved schematic diagram showing the Earth’s location in our solar system and simply drawn, nude male and female human figures that were very controversial at the time. The record included messages from U.S. president Jimmy Carter and UN secretary-general Kurt Waldheim, spoken greetings in...

  8. CHAPTER 3 How and Where Do Near-Earth Objects Form?
    (pp. 29-46)

    Mother Nature is conservative, especially when it comes to the orbital energies of her solar system bodies. During any encounter between two bodies in space, energy is conserved in that if one body gains energy during an encounter, the other one loses an equal amount of energy. For example, when the Voyager I spacecraft careened past Jupiter in 1979, the spacecraft received a huge boost in its orbital energy and Jupiter suffered an equal orbital energy loss. Of course since Jupiter is two trillion trillion times more massive that the spacecraft, it suffered far less of an effect than a...

  9. CHAPTER 4 Near-Earth Objects as the Enablers and Destroyers of Life
    (pp. 47-56)

    The evidence for impact cratering events within the solar system is obvious and ubiquitous. The first telescopic views of the moon by Galileo in 1609 immediately showed craters, and almost every solid planet or natural satellite whose surface has been observed with high enough resolution shows unmistakable evidence of impact craters. Yes, tectonic evolution, wind and water erosion on Earth, and volcanism and erosion by wind-driven dust on Mars erased many of these craters, but just how clueless could some astronomers be? How many shots across the bow did Mother Nature need to fire before astronomers finally noticed that the...

  10. CHAPTER 5 Discovering and Tracking Near-Earth Objects
    (pp. 57-78)

    Periodic active comets are considered near-Earth objects if they pass within 1.3 AU of the Sun and some of them, including comets Halley, Tempel-Tuttle, and Swift-Tuttle, have been recorded in ancient Chinese documents. Near-Earth comets have been known for a long time. For example, the 164 B.C. return of comet Halley was recorded on Babylonian clay tablets that are now housed in the British museum.¹ But comets are show-offs. When they enter into the inner solar system, their ices begin to vaporize and the resulting gases and the entrained dust particles stream away in an anti-Sunward direction, sometimes causing a...

  11. CHAPTER 6 The Nature of Asteroids and Comets
    (pp. 79-99)

    In 1960, before video games, cell phones, and the Internet, much of a youngster’s entertainment came from comic books. Disney’s Donald Duck and his fabulously wealthy Uncle Scrooge McDuck were comic book adventure heroes. In a 1960 comic book release titled “Islands in the sky,” Donald Duck, Uncle Scrooge, and Donald’s nephews Huey, Dewey, and Louie embarked upon a space adventure to the asteroid belt in a secondhand “skyfish spacewagon” rocket ship recently purchased by Uncle Scrooge. Their mission was to locate a bare, rocky little planet where Scrooge could store his money safely. During their adventures in the asteroid...

  12. CHAPTER 7 Nature’s Natural Resources and the Human Exploration of Our Solar System
    (pp. 100-108)

    The reasons for exploring and studying near-Earth objects go well beyond intellectual curiosity. These objects represent the least changed and hence most primitive objects within our solar system and, as such, they provide critical clues as to the origin of our solar system. If we wish to understand the chemical mix and thermal environment from which our solar system arose 4.6 billion years ago, then the compositions of near-Earth objects, and the meteorites derived from them, will offer insights into the conditions present when the planets formed. Armed with these clues as to the formation conditions and an albeit incomplete...

  13. CHAPTER 8 Near-Earth Objects as Threats to Earth
    (pp. 109-124)

    More than one hundred tons of near-Earth object material pummels the Earth daily. Fortunately, the vast majority of this material is dust and pebbles that are too small to survive passage through our thin atmosphere.¹ Just as hammer blows to a brick and the resulting fragments produce far more small particles than large ones, the continued collisions of near-Earth objects with other asteroids in interplanetary space over millions of years produces far more small ones than large ones. For example, there are thought to be about a thousand near-Earth objects larger than one kilometer in diameter but more than one...

  14. CHAPTER 9 Predicting the Likelihood of an Earth Impact
    (pp. 125-139)

    During the morning of October 6, 2008, Eastern Standard Time (EST), Tim Spahr, director of the Minor Planet Center (MPC), couldn’t believe what his computer was telling him. In less than twelve hours, a near-Earth asteroid would collide with Earth. Spahr had just received observations of a fast-moving, near-Earth asteroid discovered by Richard Kowalski at the Catalina Sky Survey near Tucson, and his preliminary trajectory computations, based upon these observations, suggested a nearly certain and imminent encounter with Earth. He quickly noti-fied both Lindley Johnson at NASA headquarters and Steve Chesley at the Jet Propulsion Laboratory (JPL) and posted the...

  15. CHAPTER 10 Deflecting an Earth-Threatening Near-Earth Object
    (pp. 140-154)

    Let’s assume that the unimaginable has occurred and a sizable near-Earth asteroid has been discovered on an Earth-threatening trajectory. If there is sufficient time before the predicted impact, there are numerous deflection options that can be considered.

    Science nerds love to dream up new asteroid deflection techniques. These include mounting a rocket engine on the surface of an asteroid to push it off its Earth-impact course or affixing a so-called mass driver device to the asteroid’s surface to electrostatically throw rocky material off the asteroid in one direction that would provide a small thrust in the opposite direction. Mitigation methods...

  16. REFERENCES
    (pp. 155-158)
  17. INDEX OF ASTEROID AND COMETARY OBJECTS
    (pp. 159-160)
  18. General Index
    (pp. 161-172)