The gradual wearing away of rocks through time is the process that gives rise to new deposits of sand on Earth. However, powerful asteroid impacts are likely to play a significant part in the production of fresh sand on Mars.
According to the findings of a recent study, approximately one quarter of the sand on Mars is made up of spherical fragments of glass that were formed by the high heat generated by impacts. According to Purdue University planetary scientist Briony Horgan and her colleagues, this discovery reveals how asteroid impacts contribute to shaping Mars, even long after the collisions occur. Since windblown sand sculpts the Martian landscape, this discovery reveals how asteroid impacts contribute to shaping Mars.
Horgan and his team of researchers looked at various wavelengths of visible and infrared light that were reflected from the surface of Mars using data that was obtained by satellites that were orbiting the planet. This allowed them to determine the minerals that were present in Martian sand. The research team discovered traces of glass all around the globe, notably in the more northern regions.
The combination of magma and water during volcanic eruptions is known to result in the formation of glass, therefore this could be one reason for all of that glass. The researchers point out that the region of Mars with the highest concentration of glass, which is located in the planet’s northern plains, is notably devoid of volcanoes. This eliminates the possibility that volcanic eruptions were to blame for the damage in that area and instead points to the possibility that much more devastating occurrences, such as asteroid impacts, were to blame.
Steven Goderis, a geochemist at the Vrije Universiteit Brussel in Belgium who was not engaged in the research, thinks that is a plausible hypothesis. He was not part in the research. “Mars is frequently thought of as a planet with active volcanoes. However, there is also a very significant impact component, and this is something that is sometimes ignored.
When an asteroid traveling at several kilometers per second collides with a rocky planet like Mars, the tremendous amount of energy released by the collision causes adjacent rocks to melt and be propelled into the atmosphere. This molten shrapnel breaks apart and creates pieces around the size of sand grains that are roughly spherical in shape. These fragments of glass, which are known as impact spherules, will eventually fall back down onto the surface of the planet (SN: 3/31/21).
According to the calculations made by Horgan and her colleagues, asteroid strikes over the course of the past 3 billion years are likely to have covered the surface of Mars with a layer of impact spherules measuring almost half a meter in thickness. All of that stuff ended up contributing to the sand that naturally formed on Mars as a result of erosion. According to Horgan, “impacts helped deliver sand to the surface continually over the course of time.”
In the future, scientists might have the opportunity to examine spherules that were created by impacts on Mars. The NASA rover known as Perseverance is now collecting samples of Martian sand and rocks to bring back to Earth at some point in the future (SN: 9/10/21). That, according to Horgan, is really thrilling. “The history of all of this can be found written in the sand.”