World Asteroid Day: Are asteroids truly a severe threat to humanity? By Heer Patel

The concept of an asteroid impact has often been depicted in numerous cinematic pieces, including movies and TV shows. The prospect of an asteroid impact in movies and TV shows tends to provide a tangible simulation of a probable outcome of such a scenario. Although celestial objects do enter Earth’s atmosphere, minor celestial objects often tend to enter the stratosphere, where they very frequently disintegrate harmlessly without causing any damage.  The potential threat of a significantly larger celestial body entering the Earth's atmosphere has led to sophisticated planetary defense strategies being developed.

The severity of an asteroid impact is largely correlated with its composition and size. Small objects usually around several meters in diameter, such as the meteor that had air-bursted in Chelyabinsk in 2013, had generated minor effects via its atmospheric shock waves and thermal energy without posing a significant global risk. However, objects that are approximately 50 meters in diameter, such as the one responsible for the 1908 Tunguska event, have the capacity for a large regional devastation due to their atmospheric overpressure and enormous thermal flux, leading to large forested areas being destroyed. The largest concerns are with asteroids tending to be larger than 1 km, which have historically caused extinction-level events such as the Cretaceous-Paleogene impact 66 million years ago. The impact of this magnitude would lead to a large catastrophic global phenomenon, such as mass firestorms, while impacts in the ocean would lead to immense tsunamis. Additionally, a significant amount of particulate matter and aerosols would be injected into the stratosphere, leading to global cooling. Phil Groves, the producer of the “Asteroid Hunters” documentary, had largely emphasized the destruction tied to an asteroid impact. 

In response to this large and unique vulnerability, the international scientific community has spearheaded various agencies, such as NASA's Planetary Defense Coordination Office (PDCO), due to their significant advancements in recent decades. The main element of planetary defense is the precise orbital tracking of asteroids as well as their comprehensive detection. The objective was to identify hazardous near-Earth objects (NEOs) with sufficient time to implement precise mitigation measures. Dr. Nahum Melamed from The Aerospace Corporation underscored the imperative of NEO cataloging as with future missions such as NASA's NEO Surveyor playing a large role via the usage of infrared detection which is often used due to it being less affected by asteroid albedo and can often detect objects from solar elongations which could be difficult for ground-based optical telescopes to detect. Collaborative works including the International Asteroid Warnings Network (IAWN) and the Space Mission Planning Advisory Group (SMPAG) are coordinating towards large global detection efforts for potential hazardous collisions. 

Following large threat identification, the subsequent mitigation strategies mainly validated and the currently preferred method of avoiding hazardous asteroid collision is the kinetic impactor.  This method often uses a spacecraft and directs it towards colliding with an asteroid in which transferring momentum and altering its orbital path: the Double Asteroid Redirection Test (DART) mission (also the image of this article). Dr. Andrew Rivkin, who worked on this mission, explained how this technology had modified the orbital period of Dimorphos. The post-impact analysis has shown a momentum transfer providing an augmented impulse on the asteroid, validating its use for a potential deflection of asteroids. 

Additionally, Dr. Melamed had envisioned a “toolbox” of mitigation strategies by analyzing the diverse physical properties of the asteroid, such as determining its potential tensile strength and the rotation state of the asteroid. He often advocated for a global coordination “fire station” for planetary defense, which would be a unified framework capable of rapid responses towards asteroid threats. New modern concepts in avoiding asteroid collisions are deploying solar sailing nanobots, which would revolutionize asteroid reconnaissance and enable a cost-effective method towards frequent characterization missions for asteroids, in which aerospace engineer Joe Carroll places it as being “cheaper by the dozen.” Furthermore, University of Southern California Professor Madbu Thangavelu explains the potential use of “LOSSOL” (Line of Sight Speed of Light) directed energy concept. This high-powered space laser approach offers a continuous propellantless thrust in changing the trajectory of the asteroid as it vaporizes the surface material of the asteroid, and allowing for precise, rapid deflection.

Although asteroids do represent a high-consequence long-term threat to humanity, there are currently proactive endeavors in the scientific engineering communities towards a commitment to global safety. These significant advancements have been achieved towards asteroid deflection, empirical validation of deflection capabilities, and orbital prediction. These concentrated efforts of dedicated researchers and engineers via international global collaboration and continuous technological innovations have led to humanity progressing forward by establishing the capability to prevent a potential celestial catastrophe posing a threat to mankind.

Today, June 30, World Asteroid Day serves as a powerful reminder of the potential dangers our planet faces from celestial threats. At EcoAero, our commitment to aerospace sustainability extends beyond protecting the environment — it encompasses safeguarding Earth and humanity from catastrophic risks like asteroid impacts. We hope that the day never comes when these planetary defense systems are called into action. But if it does, we are confident that the innovations and technologies developed by the global aerospace community will rise to the challenge and protect our shared future.

Image courtesy of NASA. Used for editorial purposes only. No commercial use.