One of the most important ingredients needed for life as we know it is phosphorus – and the multitude of lightning strikes that took place when the earth was young 4 billion years ago may have unlocked the necessary amount of phosphorus to create the basis for life. .
Phosphorus is needed in the molecules that form basic cell structures and cell membranes and even form the phosphate backbone of DNA and RNA, said Benjamin Hess, study author and graduate student at Yale University in the Department of Earth and Planetary Sciences.
But this element was elusive on the early earth, trapped in minerals.
“Most of the phosphorus on the early earth was trapped in minerals that are essentially insoluble and unreactive, meaning they can not be used to make biomolecules necessary for life,” Hess said. “Lightning regions offer a new mechanism for creating phosphorus in a form that can make important connections for life.”
It has long been thought that meteorites provide the necessary elements to make life on earth appear. Meteorites are known to contain schreibersite, a phosphorineral that can be dissolved in water. If enough of them had crashed to the ground, that writing site could have provided the right amount of phosphorus.
However, life began between 3.5 and 4.5 billion years ago, and it was then that fewer meteorites affected the earth.
Schreibersite has another source in the spectacles called fulgurite, also known as the glass that forms when lightning strikes the ground.
Fulgurite contains phosphorus that is released from surface rocks – and it is soluble.
“Lightning is a mechanism that does not necessarily decrease over time as the generally accepted source, meteorites, does,” Hess added. “This mechanism could be very important for considering the formation of life on Earth-like planets after meteorite impact became scarce.”
Lightning was also a topic of interest to scientists when they think of life on the early earth, as it leads to the formation of gases such as nitrogen oxides, which also played a role in the origin of life.
Hess and his fellow researchers used this existing research to investigate and refine lightning speed on early Earth.
On Earth today, we experience approximately 560 million lightning flashes per year. On the early earth, it was between 1 and 5 billion annually, with 100 to 1 billion of those hitting the ground.
Over a billion years, this could lead to 1 million lightning strikes – and lots of phosphorus.
Lightning occurs earlier on Earth because there was more carbon dioxide in the atmosphere. Carbon dioxide contributes to global temperatures, and higher global temperatures cause frequent and intense thunderstorms, Hess said.
Carbon dioxide levels were raised on early Earth after a Mars-sized object struck the earth to create the moon 4.5 billion years ago. It also released many gases from within the earth, such as carbon dioxide – which was then trapped in the earth’s atmosphere and led to more lightning, Hess said.
“Our proposal to strike lightning as an important mechanism for creating reactive phosphorus is important to our understanding of the rise of life, because lightning attacks are relatively constant through time,” Hess said.
Understanding the role of lightning as a way to create useful phosphorus has implications in the search for life outside the earth.
“Our findings are likely to apply to any planet that has an atmosphere that generates lightning. As long as a planet has a significant amount of lightning, it will have a source of phosphorus needed for the emergence of life,” Hess said. said.