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

Paper	GS Paper 3
Word Limit	250 words
Syllabus Topic	Awareness in the Fields of Space Technology

Model Answer

Asteroids are small rocky or metallic bodies that orbit the Sun. Most lie in the main asteroid belt between Mars and Jupiter. They are leftovers from the birth of the solar system. Those whose orbits come close to Earth’s are called Near-Earth Objects (NEOs).

How Real Is the Threat?

Real, because:

• The Chicxulub impact about 66 million years ago is linked to the extinction of dinosaurs.
• The Tunguska event (1908) flattened a huge forest area in Siberia.
• The Chelyabinsk meteor (2013) injured about 1,500 people in Russia.

But low probability, because:

• Extinction-level impacts by bodies over 1 km wide happen only once in millions of years.
• Most such large near-Earth asteroids have already been found and tracked.
• Apophis will pass close to Earth in 2029 but will not hit it.

So the threat is low-probability but high-impact. Smaller, city-killer asteroids are the bigger worry.

Strategies to Prevent a Catastrophe

• Detection: Sky surveys and NASA’s Planetary Defense Coordination Office track NEOs.
• Kinetic impactor: NASA’s DART hit the moonlet Dimorphos in 2022 and shortened its orbit by about 32 minutes.
• Follow-up: ESA’s Hera mission (2024) will study the DART impact site.
• Other ideas: Gravity tractor, laser ablation and nuclear deflection as a last resort.
• Global cooperation: The UN-endorsed International Asteroid Warning Network (IAWN) shares threat data.
• India: ISRO’s NETRA project builds space situational awareness.

Conclusion

Asteroids are a rare but real risk to all life. With early detection and tested deflection, humanity can avoid the fate of the dinosaurs. Planetary defence is a true global public good.

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