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Unseen Asteroid Could Mean Many Deaths

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Guaranteed, it’s the biggest meteorite explosion you will see---or might not. You may be one of the casualties. It will happen, but nobody knows when.

Thousands of orbits around the sun have been calculated. Hundreds of possible impacts on earth have been predicted by asteroids large enough to make it through the atmosphere in the upcoming years. Large enough to do “major” damage with many kills.

Thousands more orbiting rocks have been found, orbits projected, and classified as simple space debris, Near Earth Asteroids, NEAs, or Possible Hazardous Asteroids, PHAs. Earth takes on about 10,000 tons of space debris, mostly from rogue asteroids. NEAs only survive in their orbits for 10 million to 100 million years. Eventual victims of orbital decay, accretion by the sun, collisions with inner planets, or by being ejected from our solar system by near misses with planets, NEAs are a relatively dying breed.

For measuring threats of PHAs scientist now use the Wide-Field Infra-Red Survey Explorer (WISE). The most troubling information is most, 80%, midsize asteroids, 300-3000 feet, still remain undiscovered. A recent study by NASA revealed earth is actually threatened by almost 6200 separate asteroids. The most detailed study yet of PHAs by NASA used infrared scans from the 16-inch WISE telescope to identify these asteroids coming within five million miles of earth’s orbit.

Too dark to see most asteroids, one must understand estimations of 100,000-1,000,000 undiscovered asteroids are on earth crossing orbits. Eliminating the two dimensional picture, there is a map showing the relative positions of all asteroids currently within 0.3 AU of the earth. See a plan view of the solar system locating all known asteroids close to earth.

Lindley Johnson, NEO: “The NEOWISE analysis shows us we've made a good start at finding those objects that truly represent an impact hazard to Earth. But we've many more to find...” Amy Mainzer: “Our team was surprised to find the overabundance of low-inclination PHAs.”

Over 500,000 new asteroids have been found in the last 30 years. For a truly excellent impressions of asteroid distribution, The Increasing Rate of Asteroid Discovery | Space Safety Magazine by Scott Manley is astronomically (excuse the pun) one of the best videos ever. Moving and narrated orbits of each inner planet, and locations of all inner-system asteroids are pictured in thirty years of discovery.

There is always uncertainty in calculating any asteroid path due to the Yarkovsky-O’Keefe-Radzievskii-PaddacYORP effect, YORP, effect. It occurs when absorbed light from the Sun is re-emitted from the surface of the asteroid in the form of heat. The YORP effect sometimes spins asteroids. With irregular shapes heating of asteroids cannot be radiated evenly, therefore creating tiny torques and changing the spin rate and trajectory.

Gravitational effects of other planets also alters orbits of all asteroids making a close flyby, as from earth.

In March 2009 Haley A. Lovett observed asteroid 2009 DD45 missing earth by only 45,000 miles. Because most asteroids don't reflect much visible light, WISE will reveal the darkest members of the near-Earth object population observing its infrared light.

In November 2009 Claire Bates, having only 15 hours foreknowledge, realized an asteroid would pass just 8,700 miles from earth. Its orbit brought it 30 times closer than the moon.

In November 2012 asteroid 2009 VA barely missed earth by 20,400 miles, well inside the Clarke Belt of geosynchronous satellites--22,000 miles.

The recently discovered Asteroid 2011 AG5 could raise havoc in 2040 if it hits the Gravitational keyhole - Wikipedia, the free encyclopedia. Another possibility is the obscurely designated 1999 RQ36.

It seems day-by-day more dark asteroid bodies are found, more close encounters are made, and natural forces are dragging them closer in.

Bottom line, even with the current WISE orbiting equipment, a dark asteroid--NEA or PHA--will be one of the possible half-million dark objects to come knocking on our door with no warning.

Identifying ways to deflect or destroy asteroids is an option. Some ingenious ideas include nuclear weapons, painting an asteroid to change it’s heat absorption and eventual direction, and a “gravity tractor.” Other possibilities include dusting the asteroid with chalk or soot, or a solar-sail mission in which a device would sail out to the comet propelled by radiation pressure from the sun.

Interestingly Arthur C. Clarke, author, famously proclaimed: “The dinosaurs did not survive because they did not have a space program.” Without the current administration biting at their heels, NASA could become the savior of mankind.

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Kevin Roeten can be reached at roetenks@charter.net.

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