90% of Planet Killers Found: Only 20,000 City killers remain undetected

NASA gets WISE, downs estimate for near-Earth asteroid population Examiner.com Worldwide devastation and possibly an end to civilization as we know it, all the more reason to keep looking and working on planetary defense systems. ...

NASA meets asteroid discovery goal Nature.com Asteroid exploration has been a priority of US president Barack Obama and has boosted efforts onplanetary defense and near-Earth asteroid discovery. ...

NASA meets asteroid discovery Goal:

NASA is claiming a major victory as its latest calculations suggest it has reached a congressionally-mandated target of finding more than 90% of near-Earth asteroids capable of causing a planet-wide catastrophe.

Calculations using observations made by the recently-retired WISE (Wide-field Infrared Survey Explorer) telescope, shows that 911 of an estimated 981 near-Earth objects over one kilometre in size have been discovered. None are thought likely to hit Earth

"We thought this warranted a press conference. It's something we've been working towards for 12 years now," Lindley Johnson NASA's Near-Earth Object program executive, tells Nature.

In 1998, Congress mandated that NASA find 90 per cent of asteroids in this category. But in 2005, that goal was extended to include 90% of asteroids down to 140 meters in size -- and NASA is nowhere near there yet. Prospects for reaching that goal appear howver to have dramatically improved today, as calculations by the Near-Earth Object WISE team released today show that the likely population of medium-sized objects between 100 metres and one kilometer in size is smaller than thought – around 20,000 as opposed to the 35,000 that had been estimated.

Asteroid exploration has been a priority of US president Barack Obama and has boosted efforts on planetary defense and near-Earth asteroid discovery. In October 2010, the White House Office of Science and Technology Policy assigned NASA as the lead agency on planetary defense, Nature reported.

NASA Get's WISE, downs estimate for near-Earth Asteroid population

Earlier this afternoon, NASA held a press conference dealing with the subject of potentially hazardous near-Earth asteroids. While no one knew exactly what the conference was going to be about, NASA did disclose that the announcement would have to do with the Wide Field Infrared Survey Explorer (WISE)observatory, which had a 13 month mission looking for asteroids from space.

The announcement: we can breathe easier, WISE's findings have led NASA to adjust the estimate for near-Earth asteroids to about 20,000, down from over 35,000. Yes, that's still a lot of asteroids out there but that's 50% less than the old estimates.

The caveat: there could be thousands more yet to be discovered.

Rightnow, there are millions of known asteroids (and untold numbers more undiscovered) floating around the solar system, mostly in the Main Asteroid Belt, which is safely between the orbits of Mars and Jupiter. Of the millions of asteroids, over 20,000 (down from 35,000) are classified as near-Earth. Of the near-Earth objects, just over 1,100 are considered as "potentially hazardous," which is defined as an object over 500 feet in diameter that can come within 4.6 million miles of Earth.

Obviously, a metallic space rock 500 feet across traveling at up to 15 miles per second could do an immense amount of damage. For comparison, the object (most likely a comet) that caused the Tunguska Incidentwas probably less than 100 yards (300 feet across) but still leveled forests for over 1,000 square miles.

Needless to say, if such an object (even a small one) were to hit a populated area, the death toll would be apocalyptic. Large impactor? Worldwide devastation and possibly an end to civilization as we know it, all the more reason to keep looking and working on planetary defense systems.

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