According to the findings of a new study conducted by physicists at the University of Colorado in Boulder, the uneven surface of asteroids may be the consequence of dust producing a “popcorn-like effect.” The effect, when it has had enough time to work, helps to clean up smaller asteroids by making them lose dust and appear more rugged and rough from space. Recent research published in Nature Astronomy may provide a roadmap for understanding the processes that cause asteroids to undergo dramatic form shifts or travel dangerously close to Earth.
According to Science Daily, the investigation started with the sharing of a few photographs by NASA in the year 2020. These photographs were taken by a spacecraft called OSIRIS-REx, which had traveled more than one billion miles to make contact with the asteroid (191055) Bennu. In contrast to what was expected, the surface of this asteroid was not smooth but instead resembled the texture of gritty sandpaper. Additionally, large rocks were seen strewn about the exteriors of the buildings.
The discovery inspired the researchers at the University of Colorado Boulder to construct a computer simulation or models, and to conduct laboratory tests, in order to investigate the mystery of the rough surfaces of asteroids. According to Hsiang-Wen (Sean) Hsu, the lead author of the study, his team revealed that forces comparable to static electricity may be responsible for kicking the tiny grains of dust off the asteroid and into space, leaving only larger boulders behind.
For the purpose of the study, the scientists carried out a number of computations that examined the physics of the regolith on two fictitious asteroids. The calculations followed the possible formation and subsequent movement of dust over a period of hundreds of thousands of years. One of those asteroids measured close to half a mile across, while the other measured several kilometers. According to the research, when smaller grains of dust leapt onto the larger asteroid, they were unable to pick up sufficient speed to escape the larger asteroid’s gravitational pull. On the more manageable one, however, this was not the case.
Even though they appear to be locked in time, asteroids really undergo a process of change over the course of their lives. Researchers observed that Bennu and other asteroids undergo a continuous rotation that subjects their surfaces to sunlight, darkness, and sunlight once more. They said that the frequent exposure is what triggers the phenomena. The never-ending cycle of heating and a cooling effect puts strain on the enormous boulders that cover its surface; as a result, these rocks gradually develop cracks over the course of time, which allows tiny grains of dust to escape. The individual specks of dust that are kicked up into the air can reach speeds of more than 20 miles per hour. The researchers think that this phenomenon may not be unique to the asteroid Bennu, and that comparable physics may be taking place on other airless worlds such as the moon and perhaps the rings of Saturn.