[ad_1]
Phosphorus could have been condensed into asteroids during the formation of the solar system. The asteroids would then have moved to the inner planets, impacting them and stripping phosphorus. Image credit: Gemini Observatory / AURA / Lynette Cook.
New research shows that phosphorus, vital for life but quite rare, is condensed inside the asteroids of the outer solar system before returning to the Sun, where some of them ended up on Earth .
Phosphorus is one of the six main building blocks of the human body and is an essential element for other organisms. However, unlike hydrogen, oxygen, carbon, nitrogen and calcium, phosphorus is rare. This is even rarer in the rest of the solar system.
Astrobiologists follow phosphorus in the hope that this will lead them to signs of another life.
Many meteorites contain phosphorus, and knowing how phosphorus is distributed in the solar system could help scientists determine the origin of meteorites, depending on the amount and type of phosphorus they contain. .
"Phosphorus is one of the key elements of biology," says Matthew Pasek, an astrobiologist and geochemist at the University of South Florida.
Unlike other essential elements of life, phosphorus is mainly in solid form, while hydrogen, oxygen and nitrogen are often used as gas. "[Studying phosphorus] keeps us anchored in real samples of hard rock. Unlike the others, there is no obvious form of gas, so it must come from rock sources, "says Pasek. "We hope to link this to biology and life."
His recent article in the scientific journal Icarus examines the distribution of gaseous phosphorus (or "volatile") in the early solar system and what it means for the current distribution of phosphorus.
Meteorites containing phosphorus could also have brought the essential element to life on Earth. Image credit: David A. Aguilar (CfA).
From the edge
Phosphorus is thought to form in the heart of exploding stars or supernovae. In the case of our first solar system, everything that was close to the sun was sprayed, explains Pasek. As the elements moved away from the sun, they cooled down and began to condense into solids.
The question behind the document was: "If phosphorus does not react to form a solid at these high temperatures, then it may be able to form a different type of solid in the cold," says Pasek.
Gaseous phosphine (PH3) is the main volatile phase of low temperature phosphorus. Two different groups have proposed that phosphine can play an active role in the chemistry of ice on the outer edges of the solar system.
Pasek's article aims to determine how quickly phosphorus reacts with solids – "very fast," says Pasek – and then how long it would take to cool down and be attracted to warmer environments. In the end, the goal was to determine the distribution of volatile forms of phosphorus, such as phosphine, and their distribution in the solar system.
According to a theoretical model combining thermodynamics, phosphorus reaction rates with metals, and gas diffusion models, Pasek's research has shown that most of the phosphorus should be in the solar system around Saturn. "Phosphorus has been depleted as volatile throughout the developing solar system, and volatile forms of phosphorus would have been minimal, even in the colder regions of the solar nebula," the article says.
Meteorites and phosphorus
Phosphorus should also exist in a form called schreibersite, a mineral containing nickel, iron and phosphorus, he says. "We find it constantly in meteorites and in the most cometary forms. This implies that virtually all the meteorites we collect, which contain a small amount of phosphide, must be formed in this region … This study implies that phosphorus for life comes from the solid form rather than the phosphorus of ice.
Mikhail Zolotov, a research professor at Arizona State University, specializing in volatile elements on other planets, notes that abundance and phosphorus species could affect biological activity.
It is clear from previous studies on meteorites that phosphorus is mainly present in minerals rather than in gases. "Previous models of condensation of hot solar gas showed the formation of phosphorus minerals in meteorites," Zolotov explains.
While he says that Pasek's study is a "decent work", it is controversial that the movement of gas to the Sun, which was not modeled in paper, could be faster than the diffusion of gas to the Sun. the outside of the Sun. "The available data on meteorites do not indicate a decrease in phosphorus away from the sun … [and this hypothesis] remains to be confirmed by data from outside materials in the solar system, such as comets, "he explains.
For Pasek, the next step in this research is experimenting with phosphine in the laboratory and moving it into a more practical area. "We're going to take pieces of metal and expose them to phosphorus-containing gas and see how long it takes to make these rocks," he says. He will then transmit this data to his models.
The work was supported by NASA's Emerging Worlds program. NASA Astrobiology provides resources for this and other research and analysis programs within the NASA Science Missions Directorate (SMD) that solicit proposals for research in astrobiology.
Publication: Matthew A. Pasek, et al., "Phosphorus Volatility in the Early Solar Nebula," Icarus, 2018; doi: 10.1016 / j.icarus.2018.07.011
[ad_2]
Source link
