On Aug. 16, a space rock the size of a car zipped past Earth at a distance too close for comfort – approximately 1,830 miles. What’s even more disconcerting is that NASA never saw it until after it had happened.
The report said the space rock, because of its size, most likely wouldn’t have posed any danger to people on the ground had it struck our planet. But it noted that “the close call is worrisome nonetheless, since astronomers had no idea the asteroid existed until after it passed by.”
“The asteroid approached undetected from the direction of the sun,” Paul Chodas, the director of NASA’s Center for Near Earth Object Studies, told Business Insider. “We didn’t see it coming.”
The space rock was first detected, about six hours after it flew by Earth, by the Palomar Observatory in California.
The record-breaking nature of the event was confirmed by Chodas: “Yesterday’s close approach is closest on record, if you discount a few known asteroids that have actually impacted our planet,” the report quoted.
According to the report, NASA is aware of only a fraction of near-Earth objects (NEOs) like this one, as many do not cross any telescope’s line of sight, and in recent years, several potentially dangerous asteroids have snuck up on scientists. If the wrong one slipped through the gaps in our NEO-surveillance systems, it could kill tens of thousands of people, the report noted.
This recent near-Earth asteroid, initially called ZTF0DxQ, is now formally known to astronomers as 2020 QG. The Business Insider report said it first learned about it from the creator of the website orbitsimulator.com, Tony Dunn.
Dunn tweeted on Monday: “Newly-discovered asteroid ZTF0DxQ passed less than 1/4 Earth diameter yesterday, making it the closest-known flyby that didn’t hit our planet,” the report quoted.
Business Insider reported that “early observations suggest the space rock flew over the Southern Hemisphere just after 4 a.m. Universal Time (midnight ET) on Sunday.” The report said, however, that the International Astronomical Union’s Minor Planet Center calculated a slightly different trajectory, suggesting the asteroid flew over the Pacific Ocean hundreds of miles east of Australia.
Not dangerous, but it is unnerving.
According to the report, 2020 QG wasn’t too dangerous, as far as space rocks are concerned.
“Telescope observations suggest the object is between 6 feet (2 meters) and 18 feet (5.5 meters) wide – somewhere between the size of a small car and an extended-cab pickup truck,” the report said. According to the “Impact Earth” simulator from Purdue University and Imperial College London, even if it was on the largest end of that spectrum and made of dense iron, as most asteroids are rocky, only small pieces of such an asteroid may have reached the ground, the Business Insider report cited.
Such an asteroid would have exploded in the atmosphere.
According to the report, an asteroid such as this one, would have exploded in the atmosphere, creating a brilliant fireball. The airburst unleashed would have been equivalent to detonating a couple dozen kilotons of TNT, or about the same as one of the atomic bombs the U.S. dropped on Japan in 1945. However, to people on the ground, the airburst, which would have happened about 2 or 3 miles above the ground, wouldn’t have sounded any louder than heavy traffic, the report said.
It doesn’t take a huge rock to create a big problem.
However, the report noted that it does not take a huge space rock to create a big problem. In February 2013, a roughly 66-foot-wide asteroid exploded without warning over Chelyabinsk, Russia, creating a superbolide event, which unleashed an airburst equivalent to 500 kilotons of TNT – about 30 Hiroshima nuclear bombs’ worth of energy, the report said. The explosion, which began about 12 miles above Earth, triggered a blast wave, shattering windows in six Russian cities and injuring about 1,500 people.
What is considered a “potentially hazardous” NEO?
“Potentially hazardous” NEOs are defined as space objects that come within 0.05 astronomical units and measure more than 460 feet in diameter, according to NASA.
NASA is actively scanning the skies for such threats, which Congress has required it to do since 2005. However, the report said “the agency is mandated to detect only 90% of “city killer” space rocks larger than about 460 feet (140 meters) in diameter.”
In May 2019, NASA said it had found less than half of the estimated 25,000 objects of that size or larger, the report cited.
Objects that come from the direction of the sun, meanwhile – like 2020 QG – are notoriously difficult to spot, the report said.
“There’s not much we can do about detecting inbound asteroids coming from the sunward direction, as asteroids are detected using optical telescopes only (like ZTF), and we can only search for them in the night sky,” Chodas said. “The idea is that we discover them on one of their prior passages by our planet, and then make predictions years and decades in advance to see whether they have any possibility of impacting,” the report quoted Chodas.
NASA has a plan.
According to the Business Insider report, NASA has a plan to address these gaps in its asteroid-hunting program, and is in the early stages of developing a space telescope able to detect asteroids and comets coming from the sun’s direction. Nearly $36 million has been allotted in NASA’s 2020 budget for that telescope, called the Near-Earth Object Surveillance Mission. It could launch as early as 2025, if funding continues.[embedded content]
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