Asteroids are rocky celestial bodies orbiting the Sun, and their potential to cause catastrophic impacts poses a significant threat to life on Earth. While the likelihood of an extinction-level event remains low, strategies such as tracking, deflection technologies, and international collaborations have been developed to mitigate this risk.

Q16. What are asteroids? How real is the threat of them causing extinction of life? What strategies have been developed to prevent such a catastrophe?

Model Answer:

Introduction

India Space Research Organisation plans to send its spacecraft or collaborate with other space agencies to study asteroid Apophis. Asteroids are small rocky bodies that orbit the Sun, primarily found in the asteroid belt between Mars and Jupiter. They vary in size from a few meters to hundreds of kilometers across and are remnants from the early solar system.

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Threat of Asteroids in causing extinction of life

• Extinction of Dinosaurs: Recently, a study published in Journal Science confirmed that the asteroid causing the dinosaur extinction 66 million years ago originated beyond Jupiter’s orbit. 
• Chelyabinsk Meteor Explosion: In 2013, an asteroid exploded about 30 km above a Russian town, releasing energy equivalent to 26 to 33 times released by the atom bomb that detonated over Hiroshima. While most of this energy was absorbed by the atmosphere, shock waves traveled to the ground, flattened trees, damaged buildings, and injured many people.
• The potential threat of asteroids causing extinction events primarily revolves around larger bodies, particularly those greater than 1 kilometer in diameter. 
• Potential Consequences: An impact could cause widespread fires, tsunamis, and a “nuclear winter” effect from dust and debris blocking sunlight, disrupting ecosystems and agriculture.
• Less likelihood but catastrophic Impact: While the likelihood of such an impact is low in any given year, the consequences of a significant impact could be catastrophic, potentially leading to mass extinctions.
• Changing Orbits: The orbits of asteroids can be changed by Jupiter's massive gravity – and by occasional close encounters with Mars or other objects. Stray asteroids and asteroid fragments have slammed into Earth and the other planets in the past, playing a major role in altering the geological history of the planets and in the evolution of life on Earth.

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Strategies to Prevent Catastrophe

Several strategies have been developed and proposed to mitigate the threat posed by asteroids:

• Surveys: Various space agencies, including NASA and ESA, actively monitor NearEarth Objects (NEOs) using telescopes and radar.
• Early Warning Systems: The goal is to detect potential threats well in advance, ideally years or decades before a predicted impact.
• Kinetic Impactor: This involves sending a spacecraft to collide with an asteroid to change its trajectory. The successful test of NASA’s DART (Double Asteroid Redirection Test) mission demonstrated this approach.
• Gravity Tractor: A spacecraft could hover near an asteroid for an extended period, using its gravitational pull to slowly alter the asteroid’s path.
• Nuclear Disruption: In extreme cases, a nuclear device could be detonated near an asteroid to either deflect or disrupt it, though this approach raises significant safety and ethical concerns. 
• Global Efforts: Organizations like the United Nations and various space agencies work together to share data and coordinate responses to potential threats.
• Planetary Defense Conferences: These events bring together scientists, policymakers, and engineers to discuss strategies and share knowledge.

Conclusion

While the threat posed by asteroids is real, ongoing advancements in detection and deflection strategies significantly enhance our ability to prevent potential catastrophes. NASA has been actively monitoring the asteroid's path to prevent any potential mishaps. using large observatories like PanSTARRS, the Catalina Sky Survey, and NASA's NEOWISE mission, the space agency vigilantly tracks these celestial objects. Additionally, planetary radar efforts, such as  JPL's Goldstone Solar System Radar Group, are instrumental in NASA's NEO Observations Program. Continued investment in planetary defense research and international cooperation will be crucial in addressing this challenge effectively.

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