What are asteroids? How real is the threat of them causing extinction of life? What strategies have been…

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

Ghissu Editorial · Accepted Answer

Asteroids are rocky remnants of the solar system's formation, and while an extinction-level strike like Chicxulub is very rare, smaller impacts such as Chelyabinsk are a real regional threat. NASA's DART mission proved in 2022 that a kinetic impactor can deflect an asteroid.

**Introduction**

NASA's DART mission shortened the orbit of the moonlet Dimorphos by about 32 minutes in 2022, proving that an asteroid like the one that ended the dinosaurs could be deflected.

**Asteroids and the Reality of the Threat**

1. **What asteroids are**: Rocky or metallic remnants of the solar system's formation 4.6 billion years ago, mostly in the belt between Mars and Jupiter; those over 140 m passing within 0.05 astronomical units of Earth's orbit are potentially hazardous.

SKETCH: spectrum | Impactor Size and Damage
left: Local damage
right: Mass extinction
- Chelyabinsk 20 m
- Tunguska 50 m
- 140 m regional
- 1 km global
- Chicxulub 10 km

2. **Extinction is rare**: The 10 km Chicxulub impactor ended about three-quarters of species 66 million years ago, but such strikes come once in tens of millions of years, and NASA has catalogued over 90% of near-Earth asteroids above 1 km.
3. **Smaller objects are the gap**: The unseen Chelyabinsk airburst of 2013 injured about 1,500 people, and 2024 YR4 briefly showed a 3% chance of hitting Earth in 2032.

**Strategies Developed for Planetary Defence**

1. **Detection**: Pan-STARRS, ATLAS, the Vera C. Rubin Observatory and the planned NEO Surveyor track threats years ahead.
2. **Deflection**: DART's kinetic impact, which ESA's Hera will measure on arrival, joins gravity tractor and nuclear stand-off concepts.
3. **Coordination**: The UN-endorsed International Asteroid Warning Network and Space Mission Planning Advisory Group, endorsed by the UN in 2013, share warnings.

**Way Forward**

1. **India's role**: Extend ISRO's NETRA to near-Earth objects and pursue its proposed Apophis mission for the 2029 flyby.
2. **Readiness**: Add impact scenarios to NDMA plans.

**Conclusion**

Extinction by asteroid is remote, regional damage is plausible, and sustained detection with proven deflection keeps the planet defended.

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

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