47,000 asteroids that could wipe out cities

[American Patriot]

Revealed: The 47,000 asteroids that could wipe out cities – and the top 10 places that would be worst hit

• 47,000 potentially hazardous asteroids
• Would cause catastrophic damage on a city-sized scale or larger
• 10 countries likely to be worst affected identified
• Data from Nasa WISE sky-scan

By Rob Waugh
PUBLISHED: 07:34 EST, 17 May 2012 | UPDATED: 08:30 EST, 17 May 2012

Nasa's Wide Field Infrared Survey Explorer has sampled 107 'potentially hazardous' asteroids near Earth - 330ft wide or larger - to make estimates about how many are out there.
The WISE survey now estimates there are 47,000 'potentially hazardous' asteroids.


The asteroids would cause catastrophic damage, on a city-sized scale or larger. Research from the University of Southhampton has identified the countries most likely to be hit.



Nasa's Wide Field Infrared Survey Explorer has sampled 107 'potentially hazardous' (PHA) asteroids - 330ft wide or larger - to make estimates about how many are out there

THE COUNTRIES LIKELY TO BE WORST AFFECTED BY AN ASTEROID STRIKE


The top 10 countries most likely to be affected are, in in no particular order:

• China
• Indonesia
• India
• Japan
• The U.S
• The Philippines
• Italy
• Britain
• Brazil
• Nigeria

The PHAs - potentially hazardous asteroids - have the closest orbits to Earth's, coming within five million miles and they are big enough to survive passing through Earth's atmosphere and cause damage on a regional, or greater, scale.

The new results come from the asteroid-hunting portion of the WISE mission, called NEOWISE.



The project sampled 107 PHAs to make predictions about the entire population as a whole.



Findings indicate there are roughly 4,700 PHAs, plus or minus 1,500, with diameters larger than 330 feet . So far, an estimated 20 to 30 percent of these objects have been found.


Scientists have also drawn up a league table of the countries which will be worst affected in the event of an asteroid strike.


They have identified for the first time those which will suffer catastrophic loss of life or be so crippled it will be almost impossible for them to recover.


The list has been compiled by researchers from the University of Southampton using software called called NEOimpactor, short for NASA's ‘NEO’ or Near Earth Object programme.


Overall the top ten countries most at risk are: China, Indonesia, India, Japan, the U.S, the Philippines, Italy, the U.K, Brazil and Nigeria.

'The NEOWISE analysis shows us we've made a good start at finding those objects that truly represent an impact hazard to Earth,' said Lindley Johnson, program executive for the Near-Earth Object Observation Program at NASA Headquarters in Washington. 'But we've many more to find, and it will take a concerted effort during the next couple of decades to find all of them that could do serious damage or be a mission destination in the future.'



'The NEOWISE analysis shows us we've made a good start at finding those objects that truly represent an impact hazard to Earth,' said Lindley Johnson, program executive for the Near-Earth Object Observation Program at NASA Headquarters in Washington



The PHAs - potentially hazardous asteroids - have the closest orbits to Earth's, coming within five million miles and they are big enough to survive passing through Earth's atmosphere and cause damage on a regional, or greater, scale



The new analysis also suggests that about twice as many PHAs as previously thought are likely to reside in 'lower incination' orbits, which are more aligned with the plane of Earth's orbit.

Asteroids with lower-inclination orbits would be more likely to encounter Earth. They would also be easier to reach. The results therefore suggest more near-Earth objects might be available for future robotic or human missions.

Amy Mainzer at NASA's Jet Propulsion Laboratory in Pasadena, Calif.



'Everything we can learn about these objects helps us understand their origins and fate. Our team was surprised to find the overabundance of low-inclination PHAs. Because they will tend to make more close approaches to Earth, these targets can provide the best opportunities for the next generation of human and robotic exploration.'

The discovery that many PHAs tend to be bright says something about their composition; they are more likely to be either stony, like granite, or metallic. This type of information is important in assessing the space rocks' potential hazards to Earth.


The composition of the bodies would affect how quickly they might burn up in our atmosphere if an encounter were to take place.

The NEOWISE results have been accepted for publication in the Astrophysical Journal.

The WISE spacecraft scanned the sky twice in infrared light before entering hibernation mode in early 2011.



It catalogued hundreds of millions of objects, including super-luminous galaxies, stellar nurseries and closer-to-home asteroids.



The NEOWISE project snapped images of about 600 near-Earth asteroids, about 135 of which were new discoveries.

[American Patriot]

How they determined these countries, I don't know. There's nothing to explain it in the article.

[American Patriot]

NASA Survey Counts Potentially Hazardous Asteroids

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By NASA

Published: Wednesday, May. 16, 2012 - 2:13 pm

WASHINGTON, May 16, 2012 -- /PRNewswire-USNewswire/ -- Observations from NASA's Wide-field Infrared Survey Explorer (WISE) have led to the best assessment yet of our solar system's population of potentially hazardous asteroids. The results reveal new information about their total numbers, origins and the possible dangers they may pose.
(Logo: http://photos.prnewswire.com/prnh/20081007/38461LOGO)
Potentially hazardous asteroids, or PHAs, are a subset of the larger group of near-Earth asteroids. The PHAs have the closest orbits to Earth's, coming within five million miles (about eight million kilometers) and they are big enough to survive passing through Earth's atmosphere and cause damage on a regional, or greater, scale.
The new results come from the asteroid-hunting portion of the WISE mission, called NEOWISE. The project sampled 107 PHAs to make predictions about the entire population as a whole. Findings indicate there are roughly 4,700 PHAs, plus or minus 1,500, with diameters larger than 330 feet (about 100 meters). So far, an estimated 20 to 30 percent of these objects have been found.
While previous estimates of PHAs predicted similar numbers, they were rough approximations. NEOWISE has generated a more credible estimate of the objects' total numbers and sizes.
"The NEOWISE analysis shows us we've made a good start at finding those objects that truly represent an impact hazard to Earth," said Lindley Johnson, program executive for the Near-Earth Object Observation Program at NASA Headquarters in Washington. "But we've many more to find, and it will take a concerted effort during the next couple of decades to find all of them that could do serious damage or be a mission destination in the future."
The new analysis also suggests that about twice as many PHAs as previously thought are likely to reside in "lower-inclination" orbits, which are more aligned with the plane of Earth's orbit. In addition, these lower-inclination objects appear to be somewhat brighter and smaller than the other near-Earth asteroids that spend more time far away from Earth. A possible explanation is that many of the PHAs may have originated from a collision between two asteroids in the main belt lying between Mars and Jupiter. A larger body with a low-inclination orbit may have broken up in the main belt, causing some of the fragments to drift into orbits closer to Earth and eventually become PHAs.
Asteroids with lower-inclination orbits would be more likely to encounter Earth and would be easier to reach. The results therefore suggest more near-Earth objects might be available for future robotic or human missions.
"NASA's NEOWISE project, which wasn't originally planned as part of WISE, has turned out to be a huge bonus," said Amy Mainzer, NEOWISE principal investigator, at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Everything we can learn about these objects helps us understand their origins and fate. Our team was surprised to find the overabundance of low-inclination PHAs. Because they will tend to make more close approaches to Earth, these targets can provide the best opportunities for the next generation of human and robotic exploration."
The discovery that many PHAs tend to be bright says something about their composition; they are more likely to be either stony, like granite, or metallic. This type of information is important in assessing the space rocks' potential hazards to Earth. The composition of the bodies would affect how quickly they might burn up in our atmosphere if an encounter were to take place.
The WISE spacecraft scanned the sky twice in infrared light before entering hibernation mode in early 2011. It catalogued hundreds of millions of objects, including super-luminous galaxies, stellar nurseries and closer-to-home asteroids. The NEOWISE project snapped images of about 600 near-Earth asteroids, about 135 of which were new discoveries. Because the telescope detected the infrared light, or heat, of asteroids, it was able to pick up both light and dark objects, resulting in a more representative look at the entire population. The infrared data allowed astronomers to make good measurements of the asteroids' diameters and when combined with visible light observations, how much sunlight they reflect.
For more information about WISE, visit:
http://www.nasa.gov/wise
SOURCE NASA


Read more here: http://www.sacbee.com/2012/05/16/449...#storylink=cpy

[American Patriot]

Swarm of asteroids that threaten Earth

Posted by Paul Sutherland on May 17th, 2012 Here’s a picture that could really make an impact. NASA has used fresh data from a space probe to plot the distribution of all asteroids that threaten to hit the Earth. Every orange dot in the image represents a giant chunk of rock 330ft wide (100 metres) or more that is in an orbit which brings it dangerously close to our planet.

NASA plot representing the asteroids threatening the Earth. Credit: NASA/JPL

They are called potentially hazardous asteroids, or PHAs – and there could be more than 6,000 of them. Worryingly, perhaps, only 20 to 30 per cent of the estimated number of these space missiles have so far been found. A 100-metre wide asteroid is considered the smallest that could cause serious damage if it hit the ground. One that is 1 km wide would cause massive destruction while a rock 10 kilometres across would leave few survivors anywhere.
The Earth’s orbit through this cosmic minefield is shown almost edge-on in green at the centre of the picture. The host of blue dots are other asteroids that come close to us, but which are less of a threat. Those are called Near Earth Objects, or NEOs.

The snapshot of the alarming swarm as it might appear on any given day was produced using observations from a satellite called WISE, short for Wide-field Infrared Survey Explorer.
NASA say the probe has given them their best assessment yet of the number of threatening asteroids, where they came from and how much danger they pose to Earth.
Their results suggest that there are around 4,700 potentially hazardous objects – plus or minus 1,500 – with diameters larger than 330ft. It is the most accurate survey yet and was produced by the asteroid-hunting part of the WISE mission, called NEOWISE.
The survey discovered that twice as many asteroids as thought are orbiting on a similar plane, or level, as the Earth’s path round the Sun, rather than swooping in from above or below. Such “lower-inclination” orbits increase the number of times such asteroids come close, apparently.
Lindley Johnson, of the Near-Earth Object Observation Program at NASA HQ in Washington, said: “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, and it will take a concerted effort during the next couple of decades to find all of them that could do serious damage or be a mission destination in the future.”
Amy Mainzer, NEOWISE’s chif scientist at NASA’s Jet Propulsion Laboratory in California, said: “Everything we can learn about these objects helps us understand their origins and fate.
“Our team was surprised to find the overabundance of low-inclination PHAs. Because they will tend to make more close approaches to Earth, these targets can provide the best opportunities for the next generation of human and robotic exploration.”
Jay Tate runs The Spaceguard Centre, a UK observatory at Knighton, Powys, that campaigns to raise awareness about the threat from deadly asteroids.
He told Skymania: “The NEOWISE data emphasises the requirement for search programmes to detect what used to be called sub-critical sized NEOs (smaller than the 1km threshold that would cause a global ctastrophe). There is a substantial threat from smaller objects that would ‘only’ devastate a small country, especially as these smaller objects are more numerous than larger ones and so pose a more frequent hazard.
“The technology required for such a search programme is readily available, and relatively cheap, especially given the actuarial cost of the hazard. While detection is essential we must not forget the subsequent follow up process required to determine accurate orbits. The main participants in this field are amateurs, who do a splendid and vital job. However, smaller asteroids pose significant technical problems to operators of small telescopes that struggle to see faint objects. Any search programme must also address the follow up issue.”
Space scientists believe that many of the PHAs may have been produced in a collision between two asteroids in the main asteroid belt lying between Mars and Jupiter. They were later sent driting into orbits closer to Earth where they began to pose a threat.
The NEOWISE project photographed 600 near-Earth asteroids, of which around 135 were new discoveries. Its heat-sensitive infrared telescope was able to pick up both light and dark objects, resulting in a more representative survey of the entire asteroid population.