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What is an Asteroid?

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  1. What is an Asteroid?

  2. Asteroid Sizes

  3. Where are they?Where do they come from?

  4. 1 2 1 4 3

  5. How do we study asteroid?

  6. LINEAR NEO Search Systems

  7. Asteroids: Years of Discovery 1

  8. Hubble!

  9. EROS Asteroid 433

  10. Hayabusa Visiting Asteroid Itokawa

  11. Hayabusa Visiting Asteroid Itokawa

  12. Why are we interested in Asteroids?

  13. What happens if an Asteroid hits the Earth?

  14. Civilization Threatening Impact Mass Extinction Impact Earth Sterilizing Impact

  15. What Happens When an Impact Takes Place? Bolides (up to 5 MT) • Great fireworks display, no damage Tunguska-class (15 MT) impact • Damage similar to large nuclear bomb (city-killer) • Average interval for whole Earth: 100 yr. • Minor risk relative to other natural disasters(earthquakes, etc.) Larger local or regional catastrophes (e.g. 10,000 MT) • Destroys area equivalent to small country • Average interval for whole Earth: 100,000 yr. • Moderate risk relative to other natural disasters Global catastrophe (> 1 million MT) • Global environmental damage, threatening civilization • Average interval for whole Earth: 1 million years • Major risk relative to other natural disasters

  16. Could it Happen?

  17. Terrestrial Impact Frequency Hiroshima year Tunguska century Tsunami danger ten thousand yr. Global catastrophe million yr. K/T billion yr. 0.01 1 100 10,000 million 100 million TNT equivalent yield (MT)

  18. What Can We Do?

  19. Strategies • Detect Project NEO (Near Earth Objects) http://neo.jpl.nasa.gov/ • Deflect Gravitational Tractor Impactor • Destroy

  20. LINEAR NEO Search Systems

  21. Questions??

  22. Civilization Threatening Impact

  23. Mass Extinction Impact

  24. Earth Sterilizing Impact

  25. Known Kilometer-Size Near Earth Asteroids 1000 estimated total NEAs > 1 km 500 1990 1995 2000 Spaceguard official start

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