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Post Info TOPIC: Near-Earth Object Survey Act


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Near-Earth Objects
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Could Venus watch for Earth-bound asteroids?
A dedicated space-based telescope is needed to achieve a congressionally mandated goal of discovering 90% of all near-Earth asteroids down to a size of 140 metres by the year 2020, says a report NASA sent to the US Congress on Thursday. Asteroids of that size are large enough to destroy a major city or region if they strike the planet – but NASA says it does not have the money to pay for the project.
The study says Venus is the best place for the telescope. That is because space rocks within Earth's orbit – where Venus lies – are most likely to be lost in the Sun's glare, potentially catching astronomers off guard. The telescope could be placed either behind or ahead of Venus in its orbit by about 60° – the stable Lagrange points, known as L4 or L5, where the gravity of the Sun and Venus are in balance.

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2007 Planetary Defense Conference
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NASA officials say the space agency is capable of finding nearly all the asteroids that might pose a devastating hit to Earth, but there isn't enough money to pay for the task so it won't get done.
The cost to find at least 90 percent of the 20,000 potentially hazardous asteroids and comets by 2020 would be about $1 billion, according to a report NASA will release later this week. The report was previewed Monday at a Planetary Defence Conference in Washington.
Congress in 2005 asked NASA to come up with a plan to track most killer asteroids and propose how to deflect the potentially catastrophic ones.

"We know what to do, we just don't have the money" -  Simon "Pete" Worden, director of NASA's Ames Research Centre.

These are asteroids that are bigger than 460 feet in diameter - slightly smaller than the Superdome in New Orleans. They are a threat even if they don't hit Earth because if they explode while close enough - an event caused by heating in both the rock and the atmosphere - the devastation from the shockwaves is still immense. The explosion alone could have with the power of 100 million tons of dynamite, enough to devastate an entire state, such as Maryland, they said.
The agency is already tracking bigger objects, at least 3,300 feet in diameter, that could wipe out most life on Earth, much like what is theorised to have happened to dinosaurs 65 million years ago. But even that search, which has spotted 769 asteroids and comets - none of which is on course to hit Earth - is behind schedule. It's supposed to be complete by the end of next year.
NASA needs to do more to locate other smaller, but still potentially dangerous space bodies. While an Italian observatory is doing some work, the United States is the only government with an asteroid-tracking program, NASA said.
One solution would be to build a new ground telescope solely for the asteroid hunt, and piggyback that use with other agencies' telescopes for a total of $800 million. Another would be to launch a space infrared telescope that could do the job faster for $1.1 billion. But NASA program scientist Lindley Johnson said NASA and the White House called both those choices too costly.
A cheaper option would be to simply piggyback on other agencies' telescopes, a cost of about $300 million, also rejected.

"The decision of the agency is we just can't do anything about it right now" - Lindley Johnson.

Earth got a scare in 2004, when initial readings suggested an 885-foot asteroid called 99942 Apophis seemed to have a chance of hitting Earth in 2029. But more observations showed that wouldn't happen. Scientists say there is a 1-in-45,000 chance that it could hit in 2036.
They think it would mostly likely strike the Pacific Ocean, which would cause a tsunami on the U.S. West Coast the size of the devastating 2004 Indian Ocean wave.
John Logsdon, space policy director at George Washington University, said a stepped-up search for such asteroids is needed.

"You can't deflect them if you can't find them. And we can't find things that can cause massive damage" - John Logsdon.

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Near-Earth asteroids
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Asteroids are big hunks of space dust and rock that will eventually smack into Earth and end life as we know it. Or they represent the new frontier of space exploration.
Or both. It depends on how you look at it.
Experts have been wary of asteroids since they came to the conclusion that one of them ended the Age of the Dinosaurs 65 million years ago. Scientists such as Stephen Hawking warn that their relatively close proximity presents grave dangers to humankind, a point of view supported in a number of recent books, such as William Burrows' The Survival Imperative: Using Space to Save Earth and British astronomer royal Martin Rees' Our Final Hour: A Scientist's Warning.

But others consider asteroids the next landscape for scientific discovery.

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Asteroid impact
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What are the odds an asteroid or meteoroid will hit the Earth again? Pretty good, according to some scientists.
There are millions of these "rocks" out there, and about 200,000 to 400,000 of them get close enough to be classified as celestial objects that could come within range of our home planet.
But it only takes one, as anyone who has studied the dinosaurs will tell you. Many scientists believe an asteroid impact led to the extinction of the dinosaurs 65 million years ago.

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Near-Earth asteroids
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It is the stuff of nightmares and, until now, Hollywood thrillers. A huge asteroid is on a catastrophic collision course with Earth and mankind is poised to go the way of the dinosaurs.

To save the day, Nasa now plans to go where only Bruce Willis has gone before. The US space agency is drawing up plans to land an astronaut on an asteroid hurtling through space at more than 30,000 mph. It wants to know whether humans could master techniques needed to deflect such a doomsday object when it is eventually identified. The proposals are at an early stage, and a spacecraft needed just to send an astronaut that far into space exists only on the drawing board, but they are deadly serious. A smallish asteroid called Apophis has already been identified as a possible threat to Earth in 2036.

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Asteroid Number 2907
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According to Russia's Institute of Applied Astronomy, about 400 asteroids and over 30 comets currently present a potential threat to the planet.
The institute's specialists are particularly concerned about an asteroid known as Number 29075, a kilometre-wide chunk of space rock that they believe "with a large degree of certainty" will strike the Earth on December 16, 2880.

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-- Edited by Blobrana at 22:56, 2006-10-24

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Russia is prepared to repel asteroids
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Russia is prepared to repel asteroids to save Earth “if necessary,” deputy head of the Russian space agency Viktor Remishevsky said on Oct. 24.

"If necessary, Russia’s rocket-manufacturing complex can create the means in space to repulse asteroids threatening Earth" - Viktor Remishevsky.

The official stressed that saving Earth from the threat of asteroids demanded international cooperation.

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killer Asteroids
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They’re out there, hidden among a haze of stars — killer asteroids.
Now the world’s astronomers are keeping a wary eye to the skies for giant objects on a collision course with Earth.

Experts say there are about 1,100 comets and asteroids in the inner solar system that are at least a 1 kilometre across, and that any one of them could unleash a global cataclysm capable of killing millions in a single blinding flash.
On Thursday, the International Astronomical Union said it has set up a special task force to sharpen its focus on threats from such “near-Earth objects.”

"The goal is to discover these killer asteroids before they discover us" - Nick Kaiser of the University of Hawaii’s Institute for Astronomy, which hopes to train four powerful digital cameras on the heavens to watch for would-be intruders.

There are no asteroid busters to stop one right now, but scientists believe that one day a defence could be devised, such as using spacecraft to divert a killer comet.

The US Congress has asked NASA for a plan to comb the cosmos for even smaller, more distant objects, including asteroids just 1½ football fields (150 meters) across. The space agency is to catalogue their position, speed and course by 2020. Already, there are 103 objects on an “impact risk” watch list.
Scientists warn there are as many as 100,000 of these “smaller” heavenly bodies with the potential to take out entire cities or set off a tsunami like the killer wave that swept through the Indian Ocean in December 2004.

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RE: Near-Earth Object Survey Act
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NASA's search program designed to discover 90% of the NEO population (1 km in diameter or larger) within 10 years is under way. The chart below shows the cumulative total known near-Earth asteroids versus time.

web_total

The blue area shows all near-Earth asteroids while the red area shows only large near-Earth asteroids. In this context, "large" is defined as an asteroid having an absolute magnitude (H) of 18.0 or brighter which roughly corresponds to diameters of 1 km or larger.

Web link:

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Potentially Hazardous Asteroids
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On 16 Apr 2006 there were 778 known Potentially Hazardous Asteroids.

Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU (about 7,480,000 km). None of the known PHAs are on a definite collision course with Earth, although astronomers are finding new ones all the time.

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