‘Surprise’ Asteroid Gets Scary Close To Earth 12 Days After Discovery


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Andrew Follett Energy and Science Reporter
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NASA scientists say they’d need at least three years to prepare an intercept mission to an asteroid like the one that passed Earth a few days ago.

The 108 foot-wide asteroid, 2017 HX4, missed Earth by a distance equivalent to four times the distance between our planet and the moon. Scientists call it a close call that could not have been averted with just 12 days of warning.

Predicting its precise orbit would be nearly impossible if the asteroid had come closer to Earth, and there wouldn’t have been enough time to launch a mission to redirect it.

“On longer timescales I am not sure that it is possible to predict where, when or even if such an object would strike the Earth given the above uncertainties,” Dr. Joseph A. Nuth, a senior asteroid scientist at NASA’s Goddard Space Flight Center, told The Daily Caller News Foundation.

“If we did plan to stop an incoming body with a spacecraft designed to carry a nuclear device and with the equipment and software to intercept a very fast moving body we would need at least 3 – 4 years to build it without cutting too many corners prior to launch,” Nuth said.

If the asteroid hit Earth, the impact could have destroyed a city depending on its trajectory.

“The worst case scenario that I can think of would be a scenario where the very last portion of the entry track passed through a highly built up city (Manhattan, Chicago, Singapore, etc.) such that it cut through skyscrapers as it came down causing enormous secondary damage as well as the terminal impact itself in a densely populated area,” Nuth said.

Former NASA administrator Charles Bolden told reporters in 2013 that the only response to this type of “surprise” asteroid on a collision course with Earth is to “pray.”

“An asteroid estimated to be 15 to 30 meters [33 to 108 feet] in size, depending on composition, could be expected to do more damage at the surface than the Chelyabinsk Event, but certainly less than Tunguska in 1908,” Lindley Johnson, NASA’s Planetary Defense Officer([PDCO), told TheDCNF.  “It would most likely create an airburst between 10 and 20 kilometers above the Earth’s surface and do moderate damage to light structures (wood framed housing) and wooded areas.  It probably would not survive enough to create a crater on the surface, but a lot of windows would get blown out if it occurred in or near populated areas.”

The Tunguska event was an airburst of a comet or asteroid over Russia in 1908 that released 1,000 times more energy than that of the atomic bomb dropped on Hiroshima. The blast knocked down an estimated 80 million trees over an area of 830 square miles, creating a shock wave measuring a 5.0 on the Richter magnitude earthquake scale.

2017 HX4 and other small objects are dangerous because they’re hard to spot in advance and can behave unpredictably. The sheer number of these asteroids means it is unlikely they will ever all be located and 13 new objects have been discovered this month so far. Global asteroid detection programs have identified 16,202 near-Earth objects of all sizes, according to International Astronomical Union.

“This is the type of object that is not very likely to be detected more than a few weeks (at most) in advance depending on its albedo, though it is detectable at longer range,” Nuth said. “There are just so many of this size range that it is unlikely that we can ever find all of them. In addition, given the effects of YORP & Yarkovsky, [how sunlight strikes the asteroid] their orbits will be extremely difficult to predict.”

The asteroid was detected on April 26 by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii. It made its closest approach to Earth on May 8. Other rocks have slipped through the gaps in NASA’s survey grid before. In February, NASA spotted one only hours before a potential impact.

“NASA’s current detection network obviously did detect this particular asteroid and will detect many similar sized objects in the future,” Nuth said. “The PDCO would like to get an infrared detection system into orbit that would not only work full time on detection (no clouds, no daytime, etc.) but would also yield a much better estimate of the object’s size than is currently possible with ground-based, visible wavelength systems. An orbital system can look in directions that cannot be observed by ground-based telescopes.”

If the rock had been on a collision course, NASA likely wouldn’t attempt to intercept it. Instead, the space agency would warn any cities in the asteroid’s path to brace for impact and potentially evacuate.

“So for this size object – in fact for any object predicted to be less than about 50 meters in size – we would just want to detect it far enough out before impact to be able to warn population centers that might be impacted to shelter in place, much as would be done for a large tornado,” Johnson said. “However, we would have an advantage in this case if we detected a week or two before impact in that we’d be able to know the exact time, and possibly the exact location, of the impact if enough observations could be taken in the days before the event.”

In recent war games, NASA and other federal agencies were unable to deflect a simulated asteroid on course to hit Earth with four years of warning.

The “city-killer” asteroid, comparable in size to 2017 HX4, ended up landing off the Southern California coast in the simulation. Federal Emergency Management Agency (FEMA) personnel coordinated a simulated mass evacuation of the Los Angeles area to mitigate the damages of a potential tsunami.

In the event a real asteroid does hit Earth, NASA’s Planetary Defense Coordination Office would work with FEMA, the Department of Defense and other agencies to coordinate disaster responses.

Congress approved $50 million for near-earth object observations and planetary defense in 2016, up from just $4 million in 2010. This money will be spent improving NASA’s ability to detect asteroids, hopefully allowing for more warning.

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