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Thursday, June 1, 2023

UC Davis, NASA study Chelyabinsk meteor’s impact

UC Davis Professor Qing-Zhu Yin of the Department of Earth and Planetary Sciences has collaborated with an international team including NASA’s preeminent meteor astronomers in the first ever study of the Chelyabinsk meteor. The research was published Nov. 7 in the journal Science. Studies of this type, which employ experts’ knowledge, highly-practiced sets of eyes and specialized technologies have allowed researchers to tell the life story of the meteor, from its cosmic birth billions of years ago, to its turbulent and high-speed conclusion in the frozen base of Lake Chebarkul.

On Feb. 15, a decaying remnant of the extra-terrestrial Chelyabinsk meteor plunged through Earth’s atmosphere at an estimated 41,000 miles per hour, roughly 40 times the speed of a triggered bullet. The resulting shock wave, which caused significant damage, passed through the city of Chelyabinsk, shattered windows, knocked locals to the ground and prompted nearly 1,500 people to seek hospitalization.

Although less than half of one percent of the meteor remained intact by the time it collided with an ice-capped lake bed in the Siberian foothills, the Chelyabinsk meteor represents one of the very first of its kind whose trajectory and descent to Earth was captured in detail on handheld cameras. The International Sensor Network, including Earth-viewing satellites and the Comprehensive Nuclear-Test-Ban Treaty Organization’s International Monitoring System were also responsible for tracking the meteor’s journey, according to Yin.

Trajectory analysis of the Chelyabinsk Meteor indicates that it likely originated from the Flora Asteroid Family, a fragmented population of a once vast asteroid that orbits between Mars and Jupiter. Coincidentally, this population of space-rubble remains the most plausible origination site of the Chicxulub Asteroid, one of the foremost suspected killers of the dinosaurs. The possibility of slingshotting one of these massive bodies through space is largely influenced by the gravitational activities of nearby Jupiter.

“Asteroids are not in perfect circular orbits, therefore they collide and break apart, aided by Jupiter’s immense gravitational influence,” Yin said in an email interview. “Any hiccup in Jupiter’s gravitational instabilities could perturb the otherwise fairly stable orbits of the asteroids and send them into the inner part of the solar system, eventually into the collisional course with the Earth, Moon and even the Sun.”

NASA meteor astronomer Peter Jenniskens and his research colleagues have estimated that the Chelyabinsk meteor embarked upon an estimated 1.2 million year journey from the Flora Family in the asteroid belt up until its fiery encounter with earth. Upon its entry into the atmosphere, the meteor weighed 13,000 metric tons.

In an initial celestial fragmentation event experienced billions of years ago, the entirety of the Chelyabinsk meteor saw the development of stress veins. These veins are tiny cracks throughout the rock that filled with metallic substances and helped to hold the rock together for the time being. In a fortunate turn of events for Earth, when the Chelyabinsk meteor entered the atmosphere, the structural integrity of the stress veins weakened, and the rock began to fragment, causing the deposition of energy and physical mass into the surrounding environment. The largest single chunk of meteorite that remained after descent weighed only 650 kilograms, roughly 0.04 percent of the original mass, numerical figures provided by Jenniskens.

“The shock wave originated from the fragmentation event, not the impact itself. Fragmentation is key to where the energy of motion is distributed — where the rock fragmented is where the energy is deposited,” Jenniskens said.

Furthermore, the Chelyabinsk meteor is hypothesized to have deposited the equivalent energy of nearly 600 kilotons of TNT into Earth’s atmosphere, a numerical figure provided by Yin. This massive energy expenditure is approximately 30 times greater than that of the Hiroshima atomic bomb, one of the larger devastating energetic events produced by man.

The Chelyabinsk meteor has been widely classified as a “wake up call” for the international scientific community. According to Yin, the UN General Assembly recently approved measures to coordinate detection and response efforts for asteroid strikes that have the potential to obliterate urban areas and potentially destroy civilization.

“Specifically, the agency voted to create an International Asteroid Warning Network made up of scientists, observatories and space agencies around the planet to share information about newly discovered asteroids and how likely they are to impact Earth,” Yin said.

Technology will be key in the tracking of potentially hazardous Chelyabinsk-like objects that Earth may encounter in the near and distant future. The Large Synoptic Survey Telescope (LSST), a device currently being developed by another international  team headed by UC Davis’ Experimental Physics and Cosmology Professor Anthony Tyson, may assist with hazard mitigation and planetary protection strategies.

“[In 2020] the LSST will provide a comprehensive census of our solar system, including potentially hazardous asteroids as small as 100 meters in size,” Tyson said in an email interview. “A recent U.S. National Academy of Sciences study showed that LSST is the most cost-effective solution to this need for early warning.“

The Chelyabinsk meteor is a motivating reminder that serious measures should be taken to track and predict potential collisions with traveling celestial bodies. Though there remains a winded debate regarding the existence of life beyond earth, there is absolutely no doubt that the natural forces existing beyond our own atmosphere are very much alive and are capable of determining the fate of mankind.

Scientists worldwide, led in part by experts residing at UC Davis and NASA, are at the forefront of rendering processes and technologies by which we may defend ourselves from future events like the Chelyabinsk meteor.