Fri, Jun 22, 2018 - Page 7 News List

US stepping up protection from asteroids, comets

EARTH DEFENSE:Scientists have found 95% of larger nearby objects, but smaller rocks could still inflict big damage, and those from the day side are hard to detect


A meteor streaks through the sky over Chelyabinsk, Russia, on Feb. 15, 2013, in a dashboard video screengrab.

Photo: AP

The US government is stepping up efforts to protect the planet from incoming asteroids that could wipe out entire regions or even continents.

The US National Science and Technology Council on Wednesday released a report calling for improved asteroid detection, tracking and deflection.

NASA is participating, along with federal emergency, military, White House and other officials.

For now, scientists know of no asteroids or comets heading our way, but one could sneak up on us, and that is why the US government wants a better plan.

Scientists have found 95 percent of all near-Earth objects measuring 1km or bigger, but the hunt is still on for the remaining 5 percent and smaller rocks that could still inflict big damage, NASA planetary defense officer Lindley Johnson said.

NASA has cataloged 18,310 objects of all sizes. Slightly more than 800 are 140m or bigger.

There is no quick solution if a space rock is suddenly days, weeks or even months from striking, Johnson said, but added that short notice would at least give the world time to evacuate the area it might hit.

Ground telescopes are good at picking up asteroids zooming into the inner solar system and approaching from the night side of Earth, Johnson said.

What are difficult to detect are rocks that have already zipped past the Sun and are heading out of the solar system, approaching from the day side.

That is apparently what happened in 2013, when an asteroid about 20m in size suddenly appeared and exploded over Chelyabinsk, Russia, damaging thousands of buildings and causing widespread injuries.

An asteroid double or even triple in size exploded over Tunguska, Russia, in 1908, leveling 2,000km2 of forest.

According to the report, casualties could be in the millions if a similar event struck New York City.

A giant space rock wiped out the dinosaurs when it smacked into Mexico’s Yucatan Peninsula about 65 million years ago.

It would take years to attempt to turn away a potential killer asteroid — several years to build a spacecraft then another few years to get it to the target, Johnson said, adding that ideally, he would like at least 10 years’ notice.

A mission to defend the Earth could involve hitting the asteroid or comet with big, fast-moving robotic spacecraft in the hopes of changing its path; or in the worst case, launching a nuclear device not to blow up the asteroid, but to superheat its surface and blow off enough material to divert it.

All that involves current technology, Johnson said.

“Part of what this action plan is about is to investigate other technologies, techniques for both deflection and disruption of the asteroid,” he told reporters.

Most of the extra work can be done with existing funds, White House Office of Science and Technology Policy senior policy adviser Aaron Miles said, adding: “This is more about figuring out how to use those resources smartly.”

The bottom line is that the US government wants to be prepared to decide which action is best if needed, officials said.

Scientists hope to learn a lot more about asteroids from a pair of missions currently underway. NASA’s Osiris-Rex spacecraft is to reach the asteroid Bennu later this year and return samples in 2023, and Japan’s Hyabusa 2 is closing in on the asteroid Ryugu, with samples to be returned in 2020.

Forget about sending astronauts, Hollywood style.

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