- 3536 - METEORS - will we know they are coming? Astronomers are keeping an eye on Near-Earth Objects. Managed for NASA at the Jet Propulsion Laboratory, the “Center for Near Earth Object Studies” (CNEOS) accurately characterizes the orbits of all known near-Earth objects, predicts their close approaches with Earth, and makes comprehensive impact hazard assessments.
--------------------- 3536 - METEORS - will we know they are coming?
- Near-Earth objects are asteroids and comets with orbits that bring them to within 120 million miles of the Sun, which means they can circulate through the Earth’s orbital neighborhood. Most near-Earth objects are asteroids that range in size from about 10 feet to nearly 25 miles across. The Sun is 93 million miles from Earth.
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- The orbit of each object is computed by finding the elliptical path through space that best fits all the available observations, which often span many orbits over many years or decades. As more observations are made, the accuracy of an object's orbit improves dramatically, and it becomes possible to predict where an object will be years or even decades into the future and whether it could come close to Earth.
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- The majority of near-Earth objects have orbits that don’t bring them very close to Earth, and therefore pose no risk of impact, but a small fraction of them, called “potentially hazardous asteroids” require more attention.
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- These asteroids are defined as asteroids that are more than about 460 feet in size with orbits that bring them as close as within 4.6 million miles of Earth’s orbit around the Sun. CNEOS continuously monitors all known near-Earth objects to assess any impact risk they may pose.
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- The Center for Near-Earth Object Studies is home of the Sentry impact-monitoring system, which continuously performs long-term analyses of possible future orbits of hazardous asteroids. There is currently no known significant threat of impact for the next hundred years or more.
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- The Center also maintains the Scout system that continually monitors brand-new potential near-Earth object detections, even before they have been confirmed as new discoveries, to see whether any of these generally very small asteroids might pose a threat of possibly imminent impact.
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- CNEOS also supports NASA’s planetary defense efforts by leading hypothetical impact exercises to help educate national and international space and disaster response agencies on the issues they would face in an actual asteroid impact scenario.
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- For more information about the Center for Near-Earth Object Studies and to access close approach and impact-risk data for all known near-Earth objects, see: ------------------
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------------------------------- https://cneos.jpl.nasa.gov/
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- The last significant asteroid to pass Earth created the blast that was the second largest of its kind in 30 years, and the biggest since the fireball over Chelyabinsk in Russia six years ago. It went largely unnoticed until now because it blew up over the Bering Sea, off Russia's Kamchatka Peninsula.
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- The space rock exploded with 10 times the energy released by the Hiroshima atomic bomb. At about noon local time on 18 December, the asteroid barreled through the atmosphere at a speed of 20 miles per second , on a steep trajectory of seven degrees.
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- Measuring several meters in size, the space rock exploded 25.6 kilometers above the Earth's surface, with an impact energy of 173 kilotons. That was 40% the energy release of Chelyabinsk, but it was over the Bering Sea so it didn't have the same type of effect or show up in the news.
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- This fireball came in over an area not too far from routes used by commercial planes flying between North America and Asia. So researchers have been checking with airlines to see if there were any reported sightings of the event.
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- In 2005, Congress tasked NASA with finding 90% of near-Earth asteroids of 460 feet in size or larger by 2020. Space rocks of this size are so-called "problems without passports" because they are expected to affect whole regions if they collide with Earth. But scientists estimate it will take them another 30 years to fulfill this congressional directive.
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- Once an incoming object is identified, NASA has had some notable success at calculating where on Earth the impact will occur, based on a precise determination of its orbit. In June 2018, the small 10ft asteroid was discovered by a ground-based observatory in Arizona eight hours before impact.
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- The Center for Near-Earth Object Studies at Nasa's Jet Propulsion Laboratory (JPL) then made a precision determination of its orbit, which was used to calculate a probable impact location. This showed the rock was likely to hit southern Africa.
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- Just as the calculation suggested, a fireball was recorded over Botswana by security camera footage on a farm. Fragments of the object were later found in the area.
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- This event over the Bering Sea shows that larger objects can collide with us without warning, underlining the need for enhanced monitoring.
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- A more robust network would be dependent not only on ground telescopes, but space-based observatories also.
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- A mission concept in development would see a telescope called “NeoCam” launched to a gravitational balance point in space, where it would discover and characterize potentially hazardous asteroids larger than 140 meters. If the mission did not launch, projections suggested it would take us many decades to get there with the existing suite of ground-based surveys.
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- But, if you have an IR-based infrared telescope, it goes a lot faster.
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April 6, 2022 METEORS - will we know they are coming? 3536
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