Sudden flyby of asteroid by Earth shows blind spot in threat detection

The discovery of an asteroid the size of a small truck just days before it passed close to Earth on Thursday (26), while posing no threat to humans, highlighted a blind spot in our ability to predict those that might actually be able to. cause harm, say astronomers.

For years, the US special agency, NASA, has prioritized the detection of asteroids much larger and more threatening than 2023 BU, the small space rock that passed 3,500 kilometers from the Earth’s surface, closer than some satellites.

Had it been heading toward Earth, the asteroid would have been pulverized into the atmosphere, with only small fragments possibly hitting the ground.

But 2023 BU is at the smaller end of a large group, asteroids 5 to 50 meters in diameter, which also include those as large as an Olympic swimming pool.

Objects of this size are difficult to detect until they are much closer to Earth, complicating any preparedness efforts for one that could impact a populated area.

The probability of an impact on Earth by a space rock, called a meteor when it enters the atmosphere, in this size range is quite low, scaling according to the size of the asteroid: it is estimated that a 5-meter rock hits Earth once a year, and a 50-meter rock once every thousand years, according to NASA.

But with current capabilities, astronomers cannot see when such a rock hits Earth until days before it happens.

“We don’t know where most of the asteroids are that could cause local to regional devastation,” said Terik Daly, a planetary scientist at the Johns Hopkins Applied Physics Laboratory.

The nearly 20-meter meteor that exploded in 2013 over Chelyabinsk, Russia, is an event that occurs every 100 years, according to NASA’s Jet Propulsion Laboratory.

The fragment generated a shock wave that shattered tens of thousands of windows and caused $33 million in damage, and no one saw it coming before it entered Earth’s atmosphere.

Some astronomers feel that relying solely on statistical probabilities and estimates of asteroid populations is an unnecessary risk when improvements could be made to NASA’s ability to detect asteroids.

“How many natural hazards are there that we could actually do something about and prevent for $1 billion? There aren’t many,” said Daly, whose work focuses on defending Earth from dangerous asteroids.

Asteroid detection took on greater importance last year after NASA launched a refrigerator-sized spacecraft at an asteroid to test its ability to divert a potentially dangerous space rock from a collision course with Earth.