The 2013 Chelyabinsk meteorite caused a series of shock waves that damaged 7,200 buildings, broke windows, and hurt 1,500 individuals.
Its characteristics may assist to discuss specific inconsistencies in the category of near-Earth asteroids.
When the Chelyabinsk fireball blew up over the Russian sky in 2013, it left a rather unusual sort of meteorite on Earth. What identifies the Chelyabinsk meteorites and others like them is the existence of dark veins triggered by a process called shock darkening. Until recently, planetary scientists have actually not been able to recognize a nearby asteroid source of these specific meteorites.
Researchers from the University of Arizona identified an asteroid called 1998 OR2 as one likely source of shock-darkened meteorites in a current paper that was released in the Planetary Science Journal. About 1 1/2 miles wide, the near-Earth asteroid passed by Earth in close distance in April 2020. Meteorites are asteroid fragments that break off into space and crash down on Earth.
The RAPTORS system atop the Kuiper Space Sciences Building at the University of Arizona was utilized to collect information for this research study. Credit: Vishnu Reddy/University of Arizona
” Shock darkening is a modification procedure caused when something affects a planetary body hard enough that the temperatures partially or fully melt those rocks and alter their appearance both to the human eye and in our data,” stated lead study author Adam Battle, a UArizona graduate student studying planetary science. “This process has actually been seen in meteorites lot of times however has actually only been seen on asteroids in a couple of cases method out in the main asteroid belt, which is discovered between Mars and Jupiter.”
Lead author and college student studying planetary sciences Adam Battle. Credit: University of Arizona
Professor of planetary sciences Vishnu Reddy, Battles consultant and co-author of the work, discovered shock darkening on primary belt asteroids in 2013 and 2014. Together with engineering professor Roberto Furfaro, Reddy co-directs the Lunar and Planetary Laboratorys Space Domain Awareness laboratory. Battle has been operating at the lab because 2019.
” Impacts are very common in asteroids and any solid body in the planetary system because we see effect craters on these items from spacecraft images. But impact melt and shock-darkening effects on meteorites stemmed from these bodies are rare. Finding a near-Earth asteroid controlled by this process has ramifications for effect danger assessment,” Reddy stated. “Adams work has actually shown that regular chondrite asteroids can look like carbonaceous in our category tools if they are impacted by shock darkening. These 2 products have various physical strengths, which is essential when trying to deflect a dangerous asteroid.”
Fight, Reddy, and their colleagues gathered data on the surface area structure of 1998 OR2 using the RAPTORS system, a telescope atop the Kuiper Space Sciences structure on campus, and identified that it appeared like a normal chondrite asteroid. Chondrite asteroids have a lighter appearance and include the minerals olivine and pyroxene.
But when the group ran the information through a classification tool, it recommended the asteroid was rather a carbonaceous asteroid, a kind of asteroid that is relatively featureless and typically dark.
The Chergach meteorite studied by the scientists reveals evidence of shock-darkening. Credit: Adam Battle/University of Arizona
” The mismatch was one of the early things that got the task going to investigate prospective causes for the discrepancy,” Battle stated. “The asteroid is not a mixture of common chondrite and carbonaceous asteroids, but rather it is certainly an ordinary chondrite, based upon its mineralogy, which has actually been changed– likely through the shock darkening process– to appear like a carbonaceous asteroid to the classification tool.”
When the fireball over Russia produced meteorites with shock-darkened qualities, shock darkening was hypothesized in the late 1980s but didnt acquire traction and went unstudied until 2013.
Researchers, consisting of Reddy, started getting more interested in shock darkening, and Reddy soon discovered shock-darkened asteroids in the main asteroid belt. On Earth, 2%, or roughly 1,400 of about 60,000 regular chondrite meteorites have undergone some degree of shock or impact process, Battle stated.
Scientists were able to eliminate a lot of other possible reasons 1998 OR2 seemed a carbonaceous asteroid instead of a common chondrite. One possible cause for the inconsistency could be area weathering, in which direct exposure to the area environment causes changes to the asteroids surface, however if that were the case, the asteroid would appear to be a little redder in color than it is. Shock darkening is a procedure that can reduce the appearance of olivine and pyroxene while also darkening the asteroids surface to look like a carbonaceous asteroid.
Recommendation: “Physical Characterization of Near-Earth Asteroid (52768) 1998 OR2: Evidence of Shock Darkening/Impact Melt” by Adam Battle, Vishnu Reddy, Juan A. Sanchez, Benjamin Sharkey, Neil Pearson and Bryn Bowen, 4 October 2022, The Planetary Science Journal.DOI: 10.3847/ PSJ/ac7223.
Scientists from the University of Arizona recognized an asteroid understood as 1998 OR2 as one probable source of shock-darkened meteorites in a current paper that was published in the Planetary Science Journal. Teacher of planetary sciences Vishnu Reddy, Battles advisor and co-author of the work, discovered shock darkening on main belt asteroids in 2013 and 2014. “Adams work has revealed that regular chondrite asteroids can appear as carbonaceous in our category tools if they are impacted by shock darkening. One possible cause for the disparity could be space weathering, in which exposure to the area environment causes modifications to the asteroids surface, but if that were the case, the asteroid would appear to be somewhat redder in color than it is. Shock darkening is a process that can suppress the appearance of olivine and pyroxene while also darkening the asteroids surface to look like a carbonaceous asteroid.
