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Asteroid 2024 Yr4
Context:
A newly discovered asteroid, designated 2024 YR4, has caught the attention of astronomers and space agencies worldwide. With a potential impact date of December 22, 2032, the asteroid has a 1.3% chance of colliding with Earth. While this probability might seem low, it has raised questions about the potential risks and necessary precautions.
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- The asteroid measures between 40 to 100 meters across, roughly the size of a football field.
- It came closest to Earth on Christmas Day 2023, passing within 800,000 kilometres, about twice the distance to the Moon.
- The asteroid will not be visible again until 2028, and scientists have until mid-April 2024 to study it before it fades from view.
What are asteroids?
- An asteroid is a relatively small, inactive body orbiting the Sun.
- Asteroids are typically composed of rocky, dusty, and metallic materials.
- Most orbit within the main asteroid belt, between the orbits of Mars and Jupiter.
- Some follow paths that circulate into the inner solar system (including near-Earth asteroids), while others remain outside the orbit of Neptune.
What is 2024 YR4?
- 2024 YR4 is estimated to be between 40 and 90 meters (130 to 300 feet) in diameter.
- It was discovered on December 27, 2024, by the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Chile.
- The asteroid is currently rated a 3 out of 10 on the Torino Impact Hazard Scale, indicating a need for monitoring but not an immediate concern. This is similar to the initial rating of the Apophis asteroid before it was later downgraded.
Impact Risk and Destruction Potential
- 2024 YR4 has a 1% chance of crashing into Earth in 2032, with a 99% chance of missing.
- If it crashes, it could release 8 to 10 megatons of energy. While not as large as the asteroid that wiped out the dinosaurs (66 million years ago), it could still cause significant localised damage.
- For comparison, the Chelyabinsk asteroid (half the size of 2024 YR4 but still caused extensive damage and injured 1,500 people) that struck Russia in 2013 released energy equivalent to 500 kilotons of TNT—about 30 times more than the Hiroshima atomic bomb.
Frequency of Asteroid Impacts
- Thousands of small asteroids enter Earth’s atmosphere daily, most burning up and causing little damage.
- Larger asteroids capable of causing significant damage, like the Chicxulub asteroid that contributed to the extinction of dinosaurs, are much rarer, with impacts expected about once every 260 million years.
- A smaller asteroid, such as 2024 YR4, could cause widespread damage to a city depending on its size, speed, and angle of entry.
Scientific Challenges in Studying Asteroids
- Determining the exact size of asteroids like 2024 YR4 is challenging, as astronomers measure their brightness, which depends on their reflectivity.
- A larger asteroid can appear dimmer if its surface is dark, or a smaller one might appear brighter if its surface is highly reflective. This complicates the estimation of its true size.
Monitoring and Mitigation Efforts
- The International Asteroid Warning Network (IAWN) and the Space Mission Planning Advisory Group (SMPAG) are actively monitoring 2024 YR4.
- These groups are responsible for coordinating global efforts to track and potentially mitigate asteroid threats. As more data is collected, the probability of impact may decrease, as is common with newly discovered asteroids.
- NASA is working on planetary defence systems to prevent asteroid collisions with Earth.
- The Double Asteroid Redirection Test (DART) was a key mission in this effort. In 2022, a DART spacecraft successfully altered the trajectory of the Dimorphos asteroid, demonstrating a method of asteroid deflection.
- Although Dimorphos was not a threat to Earth, the mission proved that altering the path of an asteroid is a viable strategy for planetary defence.
- The Indian Space Research Organisation (ISRO) aims to be involved in planetary defence missions focusing on the closest approach of the Apophis asteroid to Earth on April 13, 2029. ISRO’s involvement in monitoring and potential mitigation strategies highlights its growing role in planetary defence efforts.
