Q. 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:

Asteroids

Asteroids are rocky, metallic objects orbiting the Sun, primarily found in the asteroid belt between Mars and Jupiter. They range from a few meters to hundreds of kilometers in diameter and are remnants from the early solar system formation.

The threat of extinction due to asteroid impact:

• The impact of a large asteroid (>1 km diameter) could cause global catastrophe through:
– Immediate destruction at impact site
– Tsunamis if impact occurs in ocean
– Global climate change due to dust and aerosols in atmosphere
– Disruption of food chains and ecosystems

• Historical context: The Chicxulub impact 66 million years ago, linked to dinosaur extinction, demonstrates the potential for mass extinction.

• Current risk: While impacts of smaller objects occur regularly, large impact events are rare. NASA estimates the chance of a civilization-ending impact in the next century at less than 0.01%.

Strategies to prevent catastrophic impacts:

• Detection and tracking:
– Near-Earth Object Observation Program by NASA
– Pan-STARRS and Catalina Sky Survey for asteroid discovery
– Development of space-based telescopes for improved detection

• Deflection methods:
– Kinetic impact: DART (Double Asteroid Redirection Test) mission successfully demonstrated this technique.
– Gravity tractor: Using spacecraft’s gravitational pull to alter asteroid’s trajectory
– Nuclear devices as a last resort for large, imminent threats

• International cooperation:
– UN-mandated International Asteroid Warning Network
– Space agencies’ collaborative efforts (NASA, ESA, JAXA) for planetary defense

• Policy measures:
– National near-Earth object preparedness strategy
– Increased funding for asteroid detection and mitigation research

Conclusion: Continued vigilance, research, and international cooperation are crucial to mitigate the rare but potentially catastrophic threat of asteroid impacts.