ASTEROID IMPACT

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ASTEROID IMPACT
Can Year 9 save Earth from destruction?
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MISSION BRIEF

• Find out the difference between an asteroid, a
  comet and a meteor
• What happens when they hit the earth?
• Did life come to earth on a comet?
• What killed the dinosaurs ?
• How can we defend ourselves?

• Find out the difference between an asteroid, a
  comet and a meteor
• What happens when they hit the earth?
• Did life come to earth on a comet?
• What killed the dinosaurs ?
• How can we defend ourselves?

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Near Earth Objects (NEOs)

• Near-Earth Objects (NEOs) are comets and
  asteroids that have been nudged by the
  gravitational attraction of nearby planets into
  orbits near earth
• COMETS are made of water ice and dust particles,
  and originally formed in the cold outer planetary
  system
• ASTEROIDS are rocks formed in the warmer inner
  solar system between the orbits of Mars and
  Jupiter.

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Near Earth Objects (NEOs)

• When asteroids collide they break up to form
  meteoroids or meteors they are called meteorites
  when they hit the ground

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How Often?Every day, Earth is hit with 25 tons
of dust and sand-sized particles. About once a
year, a car-sized asteroid hits Earths
atmosphere, creates an impressive fireball, and
burns up before reaching the surface. Every
thousand years or so, a meteoroid the size of a
football field hits Earth and causes significant
damage to the area. Every few million years, an
object large enough to threaten Earths
civilization comes along. Impact craters on
Earth, the Moon and other planetary bodies are
evidence of these occurrences. How Big? Size
of a car most likely burn up as they enter
Earths atmosphere. Smaller than one kilometer
local damage to the impact area. Size of a very
large bridge worldwide effects. Larger than one
kilometer worldwide effects.
Objects we are monitoring NOW
Animation of objects near earth
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1.2km diameter meteor crater, Arizona,
USA(caused by 80ft diameter asteroid)
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meteor crater, Arizona, USA
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meteor crater, Arizona, USA
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70km diameter Manicouagan Crater, Canada
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Meteor Shower 1998
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Meteorite
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CRATER INVESTIGATION
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Did life come to earth on a comet?
Life needs carbon-based molecules, liquid water
and an energy source For the first billion
years of Earth's existence, the formation of life
was prevented by lots of comet and asteroid
impacts that made the Earth's surface too hot for
water and carbon-based molecules. Life on Earth
began at the end of this period some 3.8 billion
years ago. The earliest known fossils on Earth
date from 3.5 billion years ago So life must
have formed during this short period. But if it
was too hot for water and carbon molecules, how
did they get there? Comets and asteroids contain
lots of water and carbon-based molecules
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Dinosaur killer?
It now seems likely that a comet or asteroid
struck near the Yucatan peninsula in Mexico some
65 million years ago and caused a massive
extinction of more than 75 of the Earth's living
organisms, including the dinosaurs. The small
mammals survived, and did very well everything
that previously ate them was killed! And
later.humans evolved from these primitive
mammals.
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Could we prevent collision with the Earth?

• Deflection best avoids collision completely.
  Easier in lower gravity, only(!) has to be moved
  by radius of earth 6700km
• Destruction - last resort - some fragments could
  still collide
• Orbit of even a billion tonne asteroid could be
  changed by
• attaching solar sails or engines to the object
• use of chemical or nuclear explosives.

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Collision detection

• Success depends on how long we have Identifying
  which NEOs are hazardous is, therefore, an
  important part in averting impacts.
• Asteroids we can predict collisions hundreds of
  years in advance.
• Comets - less warning.
• To date the orbits of around 500 Near Earth
  Asteroids larger than 1 km have been identified
  out of an estimated total of 1000.

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