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

Asteroids are rocky, airless remnants from the early solar system, primarily orbiting between Mars and Jupiter in the Asteroid Belt. There are around1.3 millionknown asteroids, and in recent years, tracking efforts have intensified due to the potential threats they pose to Earth.

## Threat of Asteroids Causing Extinction

• In NASA’s fifth biennialPlanetary Defense Interagency Tabletop Exercise, it has found that a potentially hazardous asteroid has a 72% chance of hitting Earth, highlighting potential gaps in Earth’s preparedness to prevent such an event.


• Historical Evidence:asteroid impact caused the extinction of dinosaurs 66 million years ago, as seen in Chicxulub crater in Mexico.


• Near-Earth Objects (NEOs):According to NASA (2023), over 30,000 NEOs have been discovered with about 2,300 classified as “potentially hazardous.”


• Impact Consequences:Even small asteroids (e.g., 20 meters wide) can cause significant damage. Eg- IfBennuimpacted Earth, it would release the energy equivalent to the detonation of 1.4 billion tons of TNT.


• Extinction-Level Threat:Asteroids over 1 km in size can cause global climatic effects. However, NASA estimates such impacts occur every 500,000 years, making the risk relatively low but not negligible.


• Disasters:The kinetic energy from an asteroid impact can cause earthquakes, tsunamis, and hurricanes, which can be global in impact.

## Counter Argument

• Atmospheric Protection:Earth’s atmosphere provides a natural shield, burning up most smaller asteroids before they reach the surface.


• Astronomical and Statistical Odds: The chances of a civilization-ending asteroid (larger than 10 km) hitting Earth areone in several million per year.

## Strategies developed to prevent such a catastrophe:

• Early Detection Systems:

• NASA’s Near-Earth Object Observations (NEOO)program and ESA’s Space Situational Awareness Program continuously monitor potential threats.


• ISRO has launched the Network for Space Object Tracking and Analysis (NETRA),which tracks space debris and NEOs.


• Deflection Techniques:

• DART Mission (2022): NASA’s Double Asteroid Redirection Testsuccessfully altered the orbit of an asteroid, demonstrating the feasibility of deflection.


• Gravity Tractorwhere a spacecraft can use gravitational attraction over time to gradually change an asteroid’s trajectory.


• Planetary Defense Coordination:International collaboration under the United Nations fosters information-sharing and readiness through bodies like the International Asteroid Warning Network (IAWN).

The findings from the OSIRIS-REx mission will provide valuable insights not only into the nature of asteroids but also into the broader context of planetary defense and the importance of continued vigilance in monitoring the skies.

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