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----------------- 1825 - Asteroids responsible for evolution on Earth?
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- School kids study dinosaurs with wide-eyed fascination. They really did live here. Theme parks and museums show off the bones of the extinct giants. Kids learn that the dinosaurs were killed off by an asteroid impact. The 6-mile wide asteroid impact created the end of the Cretaceous Period 65 million years ago in the evolution of life on our planet. See footnote (1) for the energy calculation.
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- There was another period, the Permian-Triassic Period, 250 million years ago that may have suffered the same asteroid fate.
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- Life on Earth began 3,500 million years ago. There must have been many more asteroid impacts during our evolution. There is evidence that 15 enormous asteroid strikes have occurred between 1,700 and 3,500 million years ago. 4 have occurred at the end of the Achaean Period, 2,500 million years ago.
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- The first living microbes appeared on Earth 3,500 million years ago. Coincident with that period was a buildup of oxygen in the atmosphere and the beginning of multi-cellular organisms.
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- Most of Earth was covered with ocean during the Achaean Period. Asteroid scars would reside on the ocean floor which would have been recycled into the Earth’s interior.
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- The oldest rock we can find are the Barbeton Greenstones in South Africa from the Achaean crust and the Pilbara Region in Western Australia.
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- Giant impacts melt rocks and create distinctive glass spherules ( little beads that look like caviar). Finding the element Iridium along side of the spherules allows radioactive dating.
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- Compiled evidence suggests the Earth was pelted by asteroids 30 miles wide. The impacts would have boiled the oceans, cooked the little dry land, and created a dust cloud locking the Sun for years. Some of these impacts would have fractured the Earth’s crust and changed the plate tectonics.
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- Now the real mystery:
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- Did these ancient extinctions create the rise of photosynthesis?
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- Did they result in the emergence of eukaryotic cells, or predatory microbes?
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- See Review #1823 for a possible explanation of why Earth gets pelted wit asteroids every 33 million years, as we pass through the disk of the Milky Way Galaxy.
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- In 2010 NASA got the congressional order to identify 90% of the Near Earth Orbiting NEO asteroids with a diameter of 1 kilometer ( 0.62miles) or larger.
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- In 2013 an 8 meter ( 59 feet) rock exploded in the atmosphere over Chelyabinsk, Russia injuring 1,600 people , mostly those looking out glass windows when they first saw the flash. The shock wave that followed the flash caused over $30 million in damage.
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- See Footnote (1) to learn the damage level of the asteroid Chicxulub that struck the Yucatan creating a crater 62 miles in diameter.
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- There are 1 million asteroids larger than 1 kilometer (0.62 miles), mostly orbiting between Mars and Jupiter. 8,000 are cataloged. Asteroids only reflect light. Using a spectrometer astronomers can determine the composition of the asteroid from this reflected light.
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--------------------- There are 3 classifications:
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-------------------- (1) carbonaceous
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-------------------- (2) silicate ( olivine)
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-------------------- (3) metallic
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- Comets are icy because they formed in the outer Solar System.
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- Asteroids are rocky because they formed in the inner Solar System, or are comets that migrated into the inner Solar System and the Sun evaporated their ice.
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- There are 500 Earth-Crossing Asteroids (NEOs). All will impact over the next 25,000,000 years. On average this calculates to an impact every 50,000 years.
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- The Congress ordered NEO search is currently using 3 telescopes , all ground based, and a single satellite with wide-field infrared survey explorer. This satellite detects the thermal glow as objects get heated by the Sun. NASA’s funding to do this
NEO search is $40 million this year.
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- That would be a cheap price tag if NASA could predict an asteroid impact in time for space jockeys to go out there and do something about it. ( This idea would make a great movie).
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- A 2017 launch of $500 million would send NEOCAM spacecraft on the mission to characterize the orbits, shapes, composition and spin rates of NEO’s. This new data would help science trace out the history of the Solar System as well as select targets for robotic deep-space missions to intercept asteroids and redirect them.
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- Lets hope such a mission to redirect an asteroid is not too late or under funded to miss our chance. The dinosaurs had no astronauts.
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- (1) The Chicxulub crater in Yucatan, Mexico is 100 kilometers across ( 62 miles0. The asteroid impact was 17,500 miles across.
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- The density of the asteroid rock was 2,700 kilograms / meter^3. (The density of water is 1,000 kg/m^3).
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- The volume of the asteroid is 2.81*10^12 m^3.
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------------------------ Mass = Density * Volume
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------------------------ m = 2.81*10^12 * 2.7*10^3 kg
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------------------------ m = 7.6*10^15 kg
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---------------------- Kinetic Energy = ½ Mass * ( velocity)^2
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---------------------- velocity = 45,000 miles / hour, ( 20,000 meters / second)
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---------------------- K E = ½ * 7.6*10^15 * 4*10^8 m^2/sec^2
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---------------------- K E = 15.2 *10^23 kg m^2 /sec^2
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--------------------- One ton of TNT = 4.2 *10^9 Joules of energy
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--------------------- Impact = 36,000,000,000,000 tons of TNT
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--------------------- Magnitude 7 Earthquake = 10^15 joules
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--------------------- Impact = 1,520,000,000 Earthquakes at one time.
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----------------------Hiroshima atomic bomb = 8.4 *10^13
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----------------------Russia’s1961 atomic bomb = 1.8 * 10*10
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-------------------- Impact = 1,500,000 atomic bombs all at once.
- (2) Request these Reviews to learn more:
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- #1769 - The mass of all known asteroids is less than the mass of the Moon. Nearly 500 NEO asteroids have been discovered.
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- #1580 - Asteroids - the bricks that build Solar Systems. Most asteroids are not spherical because they are not massive enough for the necessary gravity.
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- #1554 - Asteroids and meteorites are fossils with stories.
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- #1429 - There is an asteroid heading right towards us.
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- #1375 - There is an asteroid following us around the Sun.
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- #1309 - Vesta and Ceres asteroids get a spacecraft visitor.
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- #1296 - When as asteroid hit Manson, Iowa.
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- and more……….
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- --------------------------------------------------------------------------------------
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- to: ------- jamesdetrick@comcast.net ------ “Jim Detrick” -----------
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----- 707-536-3272 ---------------------- Saturday, February 6, 2016 -----
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