A landscape on Mercury known as the "chaotic terrain" may have released volatile material that has been stored underground.
Ever since the Mariner 10 probe approached Mercury in 1974, planetary scientists have been puzzled by a particular region that was discovered opposite a massive crater, the Carolris Basin. In the image obtained by Sailor 10, the land looks like a cluttered area of hills and uneven ground. Scientists call it "chaotic terrain."
Pictured: "Chaotic Terrain" on Mercury
Image credit: Sailor 10 captured the view of the "chaotic terrain" for the first time when it flew over Mercury in 1974 and 1975.
For decades, the main point of view about how this "chaotic terrain" was formed was related to the impact that caused the large Carolis Basin. The huge seismic waves generated by the impact may have resonated with this area, causing a large-scale earthquake, and then such a terrain was formed.
But a new study offers a different view. Alexis Rodriguez (Institute for Planetary Sciences) and his colleagues believe that this may be due to the volatile material stored in the ground volatilizing over time and gradually becoming chaotic.
"We found that the 'chaotic terrain' looked like they had suffered a significant 'loss', like you might have a mountain and all of a sudden, half of it was gone," Rodriguez explained. "But it's not sinking into the terrain: it's just 'disappearing.'"
He added that given that Mercury is a dry, airless world, the matter has nowhere to go — it must have turned into gas and evaporated.
A turbulent world
Image: "Chaotic Terrain" on Mercury
NASA's Courier spacecraft later captured close-up views of the "chaotic terrain" as it orbited Mercury between 2011 and 2015.
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution in Washington
The new study is based on observations made by NASA's Courier spacecraft, which orbited Mercury between 2011 and 2015, presenting us with a topographic map of Mercury in unprecedented detail. The probe also determined the chemical makeup of Mercury's surface, and also found many volatile elements on its surface, such as sulfur, chlorine and potassium.
The presence of these elements surprised planetary scientists, who thought that because of the proximity to the sun, mercury should have been gone with the volatile material it carried when it formed. Now, new research suggests that layers of strongly volatile material may have been around much longer than we expected under Mercury's surface.
The researchers found evidence to support their claims in craters and ejecta rays. Counting the number of craters present in the "chaotic terrain" can deduce the age of this terrain. The researchers calculated that the terrain was about 1.9 billion years old — at least 2 billion years younger than the Carolris Basin.
In addition, ejecta rays from recent craters disappeared in some areas of the "chaotic terrain". This suggests that until recently, Mercury's surface has been releasing gas and constantly changing, Rodriguez explains.
The team also found that the "chaotic terrain" was not limited to the area opposite the Carolris Basin. Areas with similar textures appear to be independent of large impacts and are distributed from both poles to the equator. It is possible that the entire crust of Mercury has highly volatile material.
"It's a fascinating study, and I think it will spur others to do more relevant research." Geochemist David Brevett (from the Johns Hopkins University Applied Physics Laboratory) said.
Redefine habitability
So, what are these layers of strongly volatile substances? Rodriguez and his team considered several possibilities, one of which included a mixture of water.
"We're not talking about ice formed by water (although it may be at some point), but water that may be contained in phytosilicates, or hydrated salts (brine)." This doesn't mean there might be lakes or caves filled with water here, it means that the water may already be trapped in minerals.
If his team can prove the presence of water on Mercury, even in minerals, this could have an impact on the definition of habitability. "Habitability and the existence or absence of life are two different concepts," he adds, "I don't think life has appeared on Mercury, but prebiotic matter is more likely to exist." ”
The same principle may apply to exoplanets, especially asteroids orbiting longer-lived stars such as red dwarfs. "Life may have a chance to emerge because during this time, planetary systems are stable." Rodriguez said, "Stable planetary systems are more likely to produce life, of course, this cannot be determined, but it certainly increases the likelihood of life existing." ”
"Yes." Brevett retorted, "But you know, Mercury has no atmosphere. It didn't have an atmosphere when it formed. And, above it, it seems unlikely that there would be a place of water and life. ”
If there were, the Bipicolombo detector would prove the existence of strong volatile minerals. The spacecraft will arrive on Mercury in 2025 (after flying past Earth next week). The Bipi Colombo will carry instruments capable of surveying Mercury, which the Courier cannot do; and the Bipi Colombo will give the final proof of the new idea.
BY: JAVIER BARBUZANO
FY: Twenty-five Joe
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