asteroids: what, where, how and why we...
TRANSCRIPT
Asteroids: What, where, how and why we care?
Dr. Harold Geller George Mason University
30 June 2016
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What is an Asteroid?
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Asteroid Sizes
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Where are they? &
Where do they come from?
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1
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3 4
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How do we study asteroids?
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LINEAR NEO Search Systems
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Asteroids: Years of Discovery
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Hubble!
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Galileo Spacecraft
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NEAR Shoemaker
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EROS Asteroid 433
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Hayabusa Visiting Asteroid Itokawa
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Hayabusa Visiting Asteroid Itokawa
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Why do we care?
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What happens if an Asteroid hits
the Earth?
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?
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Meteor Crater, Arizona
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Earth Sterilizing Impact
Mass Extinction Impact
Civilization Threatening Impact
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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
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Could it happen to us?
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Terrestrial Impact Frequency year
century
million yr.
billion yr.
ten thousand yr.
100 million million 10,000 100 1 0.01
Hiroshima
Tunguska
K/T
TNT equivalent yield (MT)
Global catastrophe
Tsunami danger
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What Can We Do?
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Strategies
• Detect Project NEO (Near Earth Objects) http://neo.jpl.nasa.gov/ • Deflect Gravitational Tractor Impactor • Destroy
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LINEAR NEO Search Systems
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Civilization Threatening Impact
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Mass Extinction Impact
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Earth Sterilizing Impact
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Known Kilometer- Size Near Earth Asteroids
1000
500
1990 1995 2000
estimated total NEAs > 1 km
Spaceguard official start
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Looks like a potato?
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Questions??
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