What are asteroids? How real is the threat of them causing extinction of life? What strategies have been developed to prevent such a catastrophe? (UPSC 2024, 15 Marks, )

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Asteroids

Asteroids are rocky bodies orbiting the Sun, primarily found in the asteroid belt between Mars and Jupiter. They vary in size and composition and have been a subject of scientific study due to their potential impact on Earth.

• Characteristics:
• Sizes range from small pebbles to hundreds of kilometers in diameter.
• Composed mainly of metals and rocky material.
• Some have their own moons.

How real is the threat of them causing extinction of life?

• Historical Evidence:
• The most notable example is the asteroid impact 66 million years ago, which caused the extinction of dinosaurs and 75% of Earth's species.
• Such events are rare but have catastrophic consequences when they occur.
• Walter Alvarez and Luis Alvarez (1980s):
• Proposed the Alvarez Hypothesis, which links the extinction of dinosaurs to an asteroid impact.
• They discovered a global layer of iridium-rich clay (a marker of extraterrestrial origin) at the Cretaceous-Paleogene boundary, pointing to a massive asteroid impact 66 million years ago.
• Current Threat Level:
• NASA monitors Near-Earth Objects (NEOs) that pose potential threats.
• The probability of a large asteroid striking Earth is low but not negligible. Smaller asteroids may cause localized damage, while large ones could have global effects.
• David Morrison, a NASA scientist who has extensively studied the threat of Near-Earth Objects (NEOs). He advocated for public awareness and the importance of monitoring and deflecting potential impactors.
• Potential Consequences:
• Massive tsunamis, wildfires, and "impact winter" due to dust blocking sunlight.
• Collapse of ecosystems and potential loss of human civilization.

What strategies have been developed to prevent such a catastrophe?

• Detection and Monitoring:
• NASA's Planetary Defense Coordination Office (PDCO) monitors asteroids and comets near Earth.
• Telescopes like Pan-STARRS and space missions such as NEOWISE track NEOs.
• Deflection Techniques:
• Kinetic Impactor: Spacecraft collide with an asteroid to change its trajectory (e.g., NASA's DART mission successfully tested this in 2022).
• Gravity Tractor: A spacecraft exerts gravitational pull over time to alter an asteroid's course.
• Nuclear Explosions: Potential use to deflect or fragment asteroids, though this carries risks of multiple impacts.
• Global Coordination:
• International organizations like the United Nations' Space Mission Planning Advisory Group (SMPAG) develop coordinated response plans.
• Collaboration between space agencies like NASA, ESA, and others to share data and resources.
• Public Awareness and Preparedness:
• Educating the public about asteroid threats and encouraging research funding for planetary defense systems.
• United Nations Office for Outer Space Affairs (UNOOSA): Established frameworks like the Space Mission Planning Advisory Group (SMPAG) to coordinate planetary defense strategies globally.

While the threat of an asteroid causing mass extinction is real, it is relatively low due to the infrequency of large impacts. Ongoing monitoring and research are essential to mitigate potential risks and ensure the safety of life on Earth.