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

GS 3

Science & Technology

2024

15 Marks

Subject: Science & Technology

Asteroids are rocky, airless remnants left over from the Solar System’s formation ≈ 4.6 billion years ago. Ranging from meter-sized boulders to dwarf-planet–scale Ceres (≈940 km), most orbit in the main belt between Mars and Jupiter, though thousands follow Earth-crossing paths and are classified as near-Earth objects (NEOs)

Assessment of Extinction-Level Threats

The discovery of 2,818 near-Earth asteroids in 2023 highlights the ongoing identification of potential threats.
Asteroids larger than 1 kilometer can cause global catastrophes through:
- Impact winter causing prolonged darkness and cooling.
- Massive tsunamis and earthquakes.
- Release of harmful gases and debris into the atmosphere.

Planetary-defense strategies

Approach	Principle & status	Merits	Limitations
Early detection	Global surveys such as NASA’s NEO Observations Program, ESA’s Flyeye, LSST, and India’s NETRA track orbits years–decades in advance.	Buys time; low cost per life saved	Coverage gaps for small, faint objects
Kinetic impactor	Hit the asteroid with a high-speed spacecraft to nudge its orbit; proven by NASA’s DART (2022), which shortened Dimorphos’ orbital period by 33 min.	Technology-ready; scalable for 50 m–500 m targets	Less effective on rubble-pile or very large bodies
Gravity tractor	Station a massive spacecraft nearby; mutual gravity slowly drags the asteroid off course (concept tested in simulations).	Gentle, precise; preserves object intact	Requires years–decades of lead time
Nuclear standoff blast	Detonate device near surface to vaporize material, creating a rocket-like plume that alters trajectory; modeled extensively, retained as last resort.	Works on large or short-warning threats	Political, legal, and debris-fragmentation risks
Civil-defense planning	Evacuation drills, impact-forecast communication protocols under UN-backed International Asteroid Warning Network (IAWN).	Saves lives if deflection fails	Only mitigates, doesn’t prevent impact

Continued investment in sky surveys, technology demonstration missions, and multinational response frameworks will convert a low-probability but high-consequence danger into a manageable natural hazard rather than an existential threat.

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