The risk of Earth colliding with another celestial body, such as a meteorite, is a topic that has been of great interest and concern for many decades. The potential for such an event is a significant threat to all life. Assessing and understanding the likelihood of such a catastrophic occurrence is essential. However, it is challenging to calculate the risk of an event that may occur once in several thousand years or even centuries. Scientists have made tremendous strides in identifying near-Earth objects (NEOs) and developing methods to mitigate their potential impact. Still, the risk of collision remains, and it is essential to continue research to understand the risks and develop strategies to protect our planet.
What is the actual risk?
The probability of an asteroid impact occurring is determined by several factors, including the number of asteroids present in our solar system, their trajectories, and the likelihood of their intersecting with Earth’s orbit. One of the challenges of assessing this risk is that there is still much to learn about the number of objects orbiting our sun that could potentially intersect with Earth. Scientists have identified over 25,000 NEOs, with new things being discovered regularly. However, many objects remain undiscovered, particularly smaller ones that could cause significant damage upon impact.
Several strategies can be used to estimate the risks posed by NEOs. One approach is calculating the average time between significant impact events on Earth based on the geological record. This data indicates that Earth experiences a massive impact event once every 100,000 years. However, this is only an average, and a collision is still possible at any time. Another approach is to use telescopes and other observation tools to monitor the skies for potentially hazardous objects and track their orbits to determine the likelihood of their intersecting with Earth’s orbit. This approach has led to identifying many NEOs and helped researchers better understand the risks posed by these objects.
Historically, humans have dealt with the risk of asteroid impacts through sheer luck. Our planet has been moved numerous times, resulting in massive extinction events and significant environmental damage. However, the dangers posed by these impacts have become increasingly apparent in modern times, and there has been a concerted effort to devise methods to mitigate these risks. One of the most promising methods is to deflect an incoming asteroid away from Earth using kinetic impactors, gravity tractors, and nuclear detonation techniques. These methods are still experimental and require further research and development to ensure their efficacy.
Several initiatives are underway to understand better and mitigate the risks posed by NEOs. The National Aeronautics and Space Administration (NASA) has established the Planetary Defense Coordination Office to coordinate efforts to monitor and track NEOs and develop methods to mitigate the risks posed by these objects. The office collaborates with other international space agencies to share data and coordinate responses to potential impact events. Additionally, private organizations such as the B612 Foundation are working to raise awareness of the risks posed by NEOs and develop technologies to protect Earth from potential impacts.
Much future work must be done to mitigate the risks posed by NEOs entirely. While current methods show promise, there is a need to develop new technologies and approaches to deflect or destroy asteroids that may be on a collision course with Earth. Additionally, there is a need to continue monitoring the skies for potentially hazardous objects and develop early warning systems that can provide enough time to enact mitigation strategies. Continued research and investment in these areas are essential to protecting our planet and ensuring the survival of all life on Earth.
The closest known hit-and-miss regarding a catastrophic asteroid strike in modern times occurred in 2013 when a meteorite burst over the Russian city of Chelyabinsk. The meteorite was estimated to be around 20 meters in size and entered Earth’s atmosphere at about 60 times the speed of sound, releasing energy equivalent to about 500 kilotons of TNT, about 30 times the energy of the atomic bomb dropped on Hiroshima.
The explosion caused widespread damage to buildings and injured over 1,500 people, mainly from broken glass caused by the shockwave. Although this event was not catastrophic on a global scale, it served as a wake-up call to the potential dangers of asteroids and the need to track better and mitigate the risks they pose.
Even more alarming, the closest known miss regarding a catastrophic asteroid strike occurred in 2019 when a previously undetected asteroid passed within 73,000 km of Earth, more intimate than many of our communication satellites in orbit. The asteroid, estimated to be about 100 meters in size, was only detected a few days before its closest approach, highlighting the need for better detection and tracking capabilities.
Fortunately, this asteroid was not on a collision course with Earth, but it could have caused significant damage and loss of life if it had been. These close encounters with asteroids serve as a reminder of the ongoing risk that Earth faces from these cosmic objects and the importance of continued vigilance and investment in asteroid detection and mitigation strategies.
Ultimately, the threat of a catastrophic impact from an asteroid is real and requires ongoing attention and investment from the global scientific community to minimize the risks and ensure the safety and survival of all life on Earth.
We are not doomed
Providing an exact number for the risk of a catastrophic asteroid strike within the next 100 years is challenging. However, based on current estimates, the probability of a significant impact event is around 1 in 50,000 to 1 in 100,000.
In closing, the risk of a catastrophic impact on Earth from a celestial body such as a meteorite cannot be ignored, as the consequences could be devastating for all life on our planet. While the likelihood of such an event occurring in our lifetime is low, we must continue to invest in research and technology that can help us better detect and track potentially hazardous objects in our solar system and develop mitigation strategies to minimize the impact of any potential impact. By working together to address this risk, we can increase our planet’s resilience and ensure all species’ survival for generations.
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This is an original article published exclusively by Space Expert. You may cite it as:
"Assessing Earth’s collision risk" in Space Expert, 2023