Asteroid Bennu: New Insights on Impact Probability and Risks
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Chapter 1: Understanding Asteroid Bennu
The asteroid Bennu, a rare target of human exploration, has been closely studied by NASA's OSIRIS-REx mission for over two years. This extended observation has led to more precise modeling of its trajectory. Unfortunately, the findings indicate a slightly increased chance of Bennu colliding with Earth compared to earlier assessments. However, the positive aspect is that it is still much more probable that it will avoid us.
Bennu, a carbon-rich asteroid first identified in 1999, is typically regarded as the second most hazardous near-Earth asteroid. This classification played a significant role in NASA's decision to focus the OSIRIS-REx mission on it. Recent research suggests that Bennu may have a structure resembling a "rubble pile," held together by its own modest gravitational pull. Despite its relatively small size of approximately 500 meters, a collision with Earth could result in catastrophic damage.
The OSIRIS-REx mission successfully collected samples last year and has since left Bennu's orbit to return to Earth. Scientists anticipate the samples will arrive in 2023, but the mission has already yielded valuable insights about Bennu, including its elevated risk of impacting our planet.
In 2135, Bennu will make a close approach to Earth, but it is not expected to pose a threat at that time. However, advancements in our understanding of its orbit indicate that there is a possibility it could pass through a "gravitational keyhole." This phenomenon could potentially alter its trajectory, leading to a future impact in the late 23rd century. According to the latest simulations, NASA estimates a 1 in 1,750 (0.057 percent) chance of Bennu colliding with Earth before 2300. The most probable date for such an impact is September 24, 2182, with a 1 in 2,700 likelihood (approximately 0.037 percent).
What Would Happen If Asteroid Bennu Hit Earth?
This video explores the potential consequences of an asteroid impact, detailing the devastation that could ensue from a collision with Bennu.
Now, astronomers are tasked with refining Bennu’s trajectory for its 2135 approach. Even minor forces, such as the thermal cycling of the asteroid’s surface—known as the Yarkovsky effect—could influence whether Bennu enters a keyhole. Insights gained from the OSIRIS-REx samples may enhance our predictive models and prepare us for the potential outcomes if Bennu were to strike Earth.
In a worst-case scenario, while Bennu would not annihilate human civilization, it could lead to widespread destruction. A land impact might create a six-mile-wide crater and cause immediate damage across hundreds of miles. The resultant dust cloud could also disrupt the climate significantly. A collision with an ocean could trigger a tsunami, severely impacting coastal areas. Although these scenarios are distant, proactive measures are essential to mitigate potential risks.
Will Asteroid Bennu Hit Earth? NASA Explains
In this video, NASA clarifies the ongoing research regarding Bennu's trajectory and the implications of its potential impact on Earth.