A massive meteor enters the Earth’s atmosphere, creating powerful shockwaves. This stunning 3D science illustration depicts a mass extinction event.
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NASA, together with the European Space Agency (ESA) and other organizations, has been dedicated to identifying and documenting all the near-Earth asteroids (NEAs) that may pose a threat to humanity and other species.
Recent data from ESA indicates that they are nearing their goal, with over 95 percent of the projected number of “planet-killer” asteroids, measuring over a kilometer in diameter, already identified. However, the situation is quite different for smaller yet more abundant space rocks. These may not cause global devastation but could still have a profound impact on major cities if they collide directly.
“There are still many potential city-killer asteroids (~100 m) that remain undiscovered in the NEA population,” explains Seth Jacobson, a professor of planetary science at Michigan State University.
Astronomers estimate that there are around 30,000 NEAs between 100 and 300 meters in diameter falling into this category. Currently, only about 7,000 asteroids of this size have been detected near Earth, indicating that over 75 percent are yet to be discovered as they orbit the sun, potentially intersecting with our planet’s path.
ESA also suggests that there are over 600 larger NEAs, measuring between 300 and 1,000 meters, that remain unknown.
However, it’s important to note that the city killers and planet killers are just a fraction of the near-Earth asteroids. They represent only a small portion.
According to ESA’s latest figures, there could be a million nearby asteroids between 30 and 100 meters in diameter, and almost 98 percent of them have yet to be identified.
Historically, we experience asteroid impacts of this size approximately once every century. The most recent incident occurred in 2013 when a bolide exploded over Russia, causing widespread damage and injuries.
A more destructive impact, resulting in an airburst, occurred in 1908 when a massive asteroid hit Siberian forest near the Tunguska River. While the area is remote, it is believed to have caused three deaths.
Recent research suggests that our modern era has experienced a relative lull in NEA impacts, and we should anticipate more frequent impacts occurring every few decades.
Increasing Surveillance
The Chelyabinsk bolide, estimated to be within the 30 to 100 meter range, demonstrated the potential damage a city-killer asteroid can cause. It may not be large enough to destroy an entire city, but a direct impact could still result in significant damage and casualties.
Now, you might be wondering if the Chelyabinsk meteoroid had already been detected. The resounding answer is no. It went completely undetected until the moment it exploded and disintegrated in the atmosphere over central Russia. Moreover, it came from the direction of the sun, which is currently a major blind spot in our NEA detection system.
An illustration of NASA’s NEO Surveyor spacecraft.
NASA
NASA aims to address this critical vulnerability in our planetary defense strategy by launching the NEO Surveyor spacecraft in the coming years. The mission’s objective is to eliminate the risk posed by all unknown asteroids wider than 140 meters, as well as most asteroids in the 100 meter range.
“Additional missions or spacecraft extensions will be necessary to achieve a comprehensive understanding of all NEAs down to the size range of the Chelyabinsk event,” explains Jacobson.
In the meantime, we can find solace in statistics. Large asteroid impacts occur approximately once every century, or perhaps once every few generations in the worst-case scenario. Fortunately, the majority of our planet’s surface is covered by oceans and wilderness, significantly reducing the risk of casualties from medium-sized NEAs.
However, it would undoubtedly be reassuring to have a more comprehensive understanding of the asteroids currently orbiting our planet. The dinosaurs would surely have agreed.
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Jessica Irvine is a tech enthusiast specializing in gadgets. From smart home devices to cutting-edge electronics, Jessica explores the world of consumer tech, offering readers comprehensive reviews, hands-on experiences, and expert insights into the coolest and most innovative gadgets on the market.
