The Chelyabinsk Meteor
What was Learned From the Chelyabinsk Meteor Strike?
By: Chantelle Macleod, Ashleigh Arcand, Michaelin Hammond, Dylan Mortensen
Figure 1. A picture captured on February 15th, 2013 of the Chelyabinsk meteor in the Earth’s atmosphere. Source: https://www.google.ca/url sa=i&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwiVgOidiavhAhXIITQIHd6DDOMQjRx6BAgBEAU&url=http%3A%2F%2Fasteroidhit.com%2Fimpact%2Fchelyabinsk-meteor&psig=AOvVaw1ZOGA60gH1yHCUSs2diRZD&ust=1554076439238684
On February 15th, 2013 an event occurred in Chelyabinsk, Russia. A asteroid entered Earth’s atmosphere and the explosion from it allowed for the development of techniques and methods to determine the composition of meteorites and what other meteors may be composed of, using x-ray fluorescence analysis (XRF). The Chelyabinsk meteor was found to be an LL5 ordinary chondrite which is characterized by low total iron and other metal concentrations. The Chelyabinsk meteor went undetected before it entered the Earth’s atmosphere which led to the development of methods to determine the trajectory of meteors including radar observation, analyzing low-frequency sound waves, and data from geostationary satellites. With the impact of the meteor the Near Earth Objects, NEO, observations program gained more popularity and more focus was given to the program. The program focuses on locating asteroids 460 feet or larger that could potentially impact Earth and cause catastrophic damage. Not only is the NEO in place but recently the National Near-Earth Object Preparedness Strategy and Action Plan were developed to allow for plans to be made and attempts to divert the object from entering Earth’s atmosphere.
The Meteor Strike
The Chelyabinsk meteorite is actually quite small in the grand scale of our solar system; however, it still went unnoticed until it reached Earth’s atmosphere. This was a real eye-opener for both the general public and scientists alike, drawing attention to the fact that more needs to be done to detect any sized asteroid far before it collides with Earth. Upon its entry, the meteorite caused a sonic boom, a blinding flash and shattered glass of homes in the town of Chelyabinsk, Russia in 2013. The asteroid itself was about 17 meters in diameter and weighed approximately 10,000 metric tons. Utilizing the available scientific understandings scientists were able to estimate that the meteor was traveling at roughly 40,000 mph and began to fragment roughly 12 to 15 miles above the Earth’s surface. The energy of the explosion was estimated to have potentially exceeded 470 kilotons of TNT.¹
Composition of the Chelyabinsk Meteor
In order to discover the components of the meteorite X-ray fluorescence analysis (XRF) was used. XRF is the method where wavelength-dispersive spectroscopic principles are used to analyze geological materials and what elements they are composed of. The XRF method works because of the behavior of atoms when they interact with radiation. When exposed to the radiation the atoms become ionized and energy is released. The energy that is released is released by a photon. The emitted photon is characteristic of a transition between specific electron orbitals in a particular element, so this allows scientists to determine what elements are present in the sample.2 The composition of the Chelyabinsk meteor fragments depended on whether the chondrite was the light gray chondrite or the black chondrite. The black chondrite was found to have higher amounts of nickel, sulfur, and iron then the light gray chondrite fragments.3
|Chemical Compound||Light-Gray Chondrite||Black Chondrite|
Table 1. Numbers are expressed as a percent of total weight from the sample. Data adapted from Composition and Structure of Chelyabinsk Meteorite.3
The composition of the meteorite is how they are classified into different categories. The Chelyabinsk meteor is an LL5 ordinary chondrite. LL chondrites have low total iron and low metal concentrations. Ordinary chondrites are a class of stony chondritic meteorites. They comprise 87% of all finds which is why they are considered ordinary. Its composition is made of about 10% meteoric iron and olivine and sulfides.3 It is estimated that the meteor was 4,452 million years old and last went through a significant shock event about 115 million years after the solar system was formed.4 Scientists concluded that the Chelyabinsk meteor came from the Flora asteroid family in the asteroid belt. In modern age understanding composition of a meteorite is a major achievement however in our thirst for more knowledge the Chelyabinsk meteorite provided more information that needed to be studied.
As we have discussed, the Chelyabinsk meteor is the largest object we have witnessed enter Earth’s atmosphere in our lifetimes, giving us reason to learn from the event. Scientists came to the conclusion that some pieces of the original meteor were formed within the first four million years of the history of the solar system, adding size and pieces until the day it came into contact with another object which led the Chelyabinsk meteor to Earth.5 This allowed scientists to come to the conclusion that there are many more threats that could be close to our atmosphere that could do way more damage. Perhaps the most important is the planet needs to “wake up” when it comes to the possibility of objects entering the atmosphere. With the meteor being roughly the size of a six-story building, it went unnoticed for far too long as it entered our atmosphere.
This led NASA to develop a team dedicated to detecting these threats and using models created from the explosion of the meteor, it allows them to predict path’s, sizes, and possible damage of other objects.6 As they continued to research the event, scientists found that most of the damage from the meteor came from the air blasts of the debris, instead of the impact of the debris itself. For example, glass shards from exploding windows. Scientists should look into different compositions of windows to attempt to reduce this threat. Scientists utilized every ounce of information provided by this meteorite this also allowed them to confirm and tuning methods of predicting meteorite entry.
Predicting Entry of Meteors
The most important piece of information that scientists learned from the event is the possibility of something like this happening again is higher than we think, and something needs to be put in place for a catastrophe to be avoided. Scientists have learned patterns, compositions, and the history of meteors from the event, which gives viable information regarding other objects that could enter our atmosphere.
There are different types of methods used by scientists to determine the trajectory of meteors and some of the ones used for the Chelyabinsk meteor include radar observation, analyzing low-frequency sounds waves known as infrasound, optical data as well as data from geostationary satellites. All have their strengths and weaknesses.
Radar Observation Method
The first method is radar observation which provides measurements of the range and azimuth between a ground station and the meteor so giving the meteor’s position, and the Doppler shift in the returning signal can be used to estimate speed. Multiple observations can provide accurate estimates for meteor trajectory.7 Although, there are many regions not covered by radar and therefore no observations will be available for a meteor if it falls in such an area.7
Another approach is analyzing low-frequency sound waves (infrasound) produced by the passage of a meteor through the atmosphere. Data from infrasound stations can be used to estimate the meteor’s kinetic energy and by using multiple microphones and several stations, helps provide data on the meteors trajectory.7 Since stations can be and are spread out across the planet, there a greater chance to detect a meteor using infrasound than by radar.
There are still uncertainties about infrasound measurements, and the computed orbital elements will be more uncertain as well, particularly as it is hard to estimate the trajectory unless combining infrasound with a secondary source of data.7 Although, in many cases, this is not possible, which means the trajectory estimate will either be very inaccurate or entirely missing.7 Therefore, while infrasound is helpful there remain disadvantages to using infrasound.
Optical Data Method
The other approach is optical data which has been used for the Chelyabinsk meteor and this approach uses data from images or videos to estimate trajectory. If two or more cameras capture images of a meteor, than the camera positions and meteor azimuth and elevation within the images can be used to triangulate the meteor’s position.7 As with infrasound, the second set of measurements at a different time can be used to estimate the velocity. The optical data method was used by quite a few people because of the number of videos and images captured from bystanders during the Chelyabinsk event. This method is appealing because it doesn’t require specialized equipment and a number of source cameras can be used. Along with everyday use of cameras, there are numerous professional camera networks that are specifically designed to capture images of objects that enter the atmosphere.
Geostationary Satellite Method
Another method was used from geostationary satellites that typically generate images of Earth across multiple wavelengths, both in visible and infrared regions of the spectrum with a relatively frequent image capture time between 5 & 30 minutes.7 Each pixel within a satellite image is ‘geolocated’ so that it corresponds to a particular latitude and longitude on the Earth.7 This is useful when analyzing the land surface but problematic when examining features at high altitudes because the parallax effect means that geolocation for these features will be incorrect.7 The apparent position of the feature will be shifted relative to its actual position by an amount proportional to its altitude and the angle between it and the point directly below the satellite.7 Parallax correction tools exist for the use within meteorological analysis of satellite image that use an estimate of cloud height to correct for this shift and display the cloud at its correct location above the Earth.7
The trail of the meteor was visible from 3 of the Meteosat Second Generation (MSG) series of satellites.7 Two clear identifiable points on the trail were picked out in these images and used for determining the meteor’s position with the parallax correction method.7 This helped pinpoint the Chelyabinsk azimuth and slope as it moved through the atmosphere. By understanding the trajectories of meteorites we were able to further utilize this information to devise strategies to prevent and prepare for another potential meteor strike.
Future Prevention and Preparation
After an Earth-shaking event such as the Chelyabinsk meteor strike the top priority has become how to prevent it from happening again. Events such as this and many others directly influenced the development of protocols, theories, and plans in order to monitor and handle situations dealing with near-Earth objects. NASA has been at the forefront of this critical system development. At roughly the same time as the Chelyabinsk meteor event, NASA’s near-earth object (NEO) observations program was growing in popularity due to the increased awareness of the risk of an asteroid impact.8 This NEO observations program focuses on locating asteroids 460 feet and larger that could potentially impact Earth and cause catastrophic damage. The intention behind this program is to locate the majority of asteroids early enough to permit deflection or at least allow preparations for impact mitigation.8
The Planetary Defense Coordination Office
In early 2016 NASA established the Planetary Defense Coordination Office (PDCO) whose sole responsibility is to ensure early detection of potentially dangerous NEO. This is a very mild description of the PDCO their job is actually a lot more than just location NEO that poses a hazard of impacting Earth. They also are tasked with “Characterizing those objects to determine their orbit trajectory, size, shape, mass, composition, rational dynamics, and other parameters, so that experts can determine the severity of the potential impact event, warn of its timing and potential effects, and determine the means to mitigate the impact;”9 Furthermore they are also responsible for planning the appropriate action that would be necessary to deflect or disrupt NEO that is on a collision course with Earth and also implement this plan. If the NEO’s course cannot be altered they are also responsible to mitigate the effects of the collision and protect lives.9 The Planetary Defense Coordination Office plays a large role in keeping the Earth safe from near-earth objects by detecting the impending collision early enough better preparation can be conducted and possible deflection measures can be taken.
The National Near-Earth Object Preparedness Strategy and Action Plan
Even though we don’t hear much about asteroids and meteors colliding with Earth in the past couple years this doesn’t mean that advancement’s and protocols aren’t being developed. In June 2018 the National Science and Technology Council released a National Near-Earth Object Preparedness Strategy and Action Plan. This document depicted five main objectives for protecting Earth from NEO’s, this would hopefully increase accuracy, decrease uncertainty and allow for effective decision-making when NEO’s pose a threat to Earth.
In summary of the document, the first objective is to hopefully recruit any existing or planned telescope programs in hopes to improve detection and tracking through an increased volume and quality of data stream. The second objective is to improve modeling, prediction, and information integration across multiple agencies, this would potentially aid in locating if, when, and where an asteroid could strike and hopefully allow emergency service teams to be prepared for the impending collision. The third goal was a direct request to NASA to develop new ways to deflect asteroids on a collision course to Earth, specifically developing new technology for rapid response NEO reconnaissance missions; this would hopefully redirect asteroids from their impending collision course. The fourth objective is to bring together the world and create better cooperation between countries thus ensuring the safety of the planet as a whole. Finally, the last objective is directed to policymakers in the United States to develop an emergency protocol in case a large asteroid is going to strike Earth.10 Periodic advancements is needed to better prepare the world for impending asteroid strikes, this issue breaks the boundaries of nationality, religion, and culture, letting science do what is best for humanity as a whole.
An undetected space rock struck Chelyabinsk, Russia on February 15th, 2013 bringing scientists to the forefront to explain, characterize, and prevent this event from happening again. After analyzing the findings from this meteor strike, what we have found effectively answers the question: What was learned from the Chelyabinsk meteor strike? The Chelyabinsk meteorite rivalled that of a nuclear explosion drawing attention to the fact of how little is known about asteroids. The composition told us an exciting story of the possible origin and age of the asteroid, utilizing X-ray fluorescent analysis scientists provided answers to the story. Teams that were formed to study the event generated accurate models of this meteorite, these methods are used to predict asteroid size, impact power, and trajectories. These teams specifically worked on techniques such as infrasound, radar observations, and geostationary satellites. Utilizing information provided by these improved methods society created plans and groups for the future protection of the Earth. The Planetary Defense Coordination Office and NASA’s near-earth object (NEO) observations program are just two examples of societies motivation on this topic. Although the Chelyabinsk meteorite was devastating in its own right, what was gathered from the event has provided information to help us better prepare for what could potentially be out there in our universe.
- E. Howell. Chelyabinsk Meteor: A Wake-Up Call For Earth.https://www.space.com/33623-chelyabinsk-meteor-wake-up-call-for-earth.html (Assessed 24 February 2019)
- K. Wirth, A. Barth. X-Ray Fluorescence (XRF).https://serc.carleton.edu/research_education/geochemsheets/techniques/XRF.html (Assessed 25 February 2019)
- V. A. Koroteev, S. V. Berzin, Yu. V. Erokhin, K. S. Ivanov, and V. V. Khiller, Doklady Earth Sci, 451 , part 2 839 (2013)
- UC Davis. First Study results of Russian Chelyabinsk meteor published.https://phys.org/news/2013-11-results-russian-chelyabinsk-meteor-published.html (Assessed 25 February 2019)
- Radio Free Europe, Radio Liberty. Explainer: What have scientists learned from the Chelyabinsk meteor? https://www.rferl.org/a/explainer-meteor-russia/25161323.html(Assessed 26 February 2019)
- R. Naeye. Lessons from the Russian Meteor.https://www.skyandtelescope.com/astronomy-news/lessons-from-the-russian-meteor-blast/(Assessed 26 February 2019)
- S.R Proud. Reconstructing the orbit of the Chelyabinsk meteor using satellite observations.https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/grl.50660 (Assessed 13 March 2019)
- NASA. Five Years after the Chelyabinsk Meteor: NASA leads Efforts in Planetary Defense.https://www.nasa.gov/feature/five-years-after-the-chelyabinsk-meteor-nasa-leads-efforts-in-planetary-defense (Assessed 24 February 2019 )
- NASA. Planetary Defense Frequently Asked Questions.https://www.nasa.gov/planetarydefense/faq (Assessed 24 February 2019)
- H. Weitering. This is NASA’s New Plan to Detect and Destroy Asteroids Before They Hit Earth. h ttps://www.space.com/40943-nasa-asteroid-defense-plan.html (Assessed 24 February 2019)