upon October 19, 2017an astronomer with Pan-STARRS survey We detected the first interstellar object (ISO) passing through our solar system. 1I/2017 U1 This object, known as ‘Oumuamua, has stimulated significant scientific debate and remains controversial.
One thing everyone could agree on was that the detection of this object indicates that ISOs are regularly intruding into our solar system. Furthermore, subsequent research revealed that some of these objects sometimes come to Earth as meteorites and impact the surface.
This raises a very important question. If ISOs have been coming to Earth billions of years ago, could they have brought the ingredients of life with them?
in recent papersA team of researchers considered the effects of ISO in causing panspermia, the theory that the seeds of life exist throughout the universe and are distributed by asteroids, comets, and other celestial bodies.
According to the results, ISO could potentially seed hundreds of thousands (or perhaps billions) of Earth-like planets throughout the Milky Way.
The team was led by University senior David Kao. Thomas Jefferson High School of Science and Technology (TJSST). He was joined by Peter Pravchanis an associate professor of physics and astronomy at George Mason University (GMU) and director of the Mason Observatory. michael summersprofessor of astrophysics and planetary science at GMU.
Their paper, “Impact of ‘Oumuamua on panspermia” was recently posted online and is being reviewed for publication by the American Astronomical Society (AAS).
To briefly summarize, panspermia is the theory that life was brought to Earth by objects from the interstellar medium (ISM). According to this theory, this life took the form of extremophile bacteria that could survive in the harsh conditions of space.
Through this process, life is distributed throughout the universe until objects pass through the ISM and reach and impact potentially habitable planets. For this reason, panspermia is very different from competing theories about how life on Earth began (also known as abiogenesis). The most widely accepted theory is RNA world hypothesis.
This hypothesis states that RNA preceded DNA and proteins in evolution and ultimately led to the first life (i.e., indigenously originating life) on Earth.
But as Cao told Universe Today via email, panspermia is difficult to assess.
“Panspermia is difficult to assess because it has to incorporate so many different factors, many of which are open-ended and unknown. For example, the physics behind panspermia (the earliest fossilized evidence We need to take into account the number of objects that hit the Earth before our lifetime? ), biological factors (can extremophiles survive supernova gamma rays?), etc.
“In addition to each of these factors, there are questions that we don’t yet have answers to or can’t model effectively. For example, if an object containing life were to collide with Earth, would it actually reach Earth?” such as the number and probability of extremophiles.These factors, combined with other factors such as changes in the rate of star formation and the recent detection of several rogue planets, make it difficult to assess panspermia.Panspermia Our understanding of the validity of is constantly changing.”
The detection of ‘Oumuamua in 2017 was a major turning point for astronomy, as it was the first time that ISO had been observed.
The fact that it was detected indicates that such objects are statistically significant in the Universe, and that ISOs are likely to have passed through the Solar System on a regular basis (some of them probably to still be here).
Two years later, a second ISO was detected entering the solar system (2I/Borisov), but this time there was no mystery about its nature. As it approached the Sun, 2I/Borisov formed a tail, indicating it was a comet.
Subsequent research revealed that some of these objects meteorite hitting the earth’s surface, some have been identified.This too CNEOS 2014-01-08A meteorite that collided with. Pacific in 2014 (and it was the subject of research) galileo project).
As Cao explained, the detection of these interstellar visitors also has implications for panspermia and the ongoing debate about the origins of life on Earth.
“Oumuamua serves as a new data point for the panspermia model. Its physical properties, in particular its mass, size (sphere radius), and implied ISM number density, can be used to calculate the number density of objects in the interstellar medium. These models can be used to estimate the magnetic flux density and mass flux of objects in the interstellar medium, and the total number of objects that have impacted the Earth over 800 million years. It can be estimated (this is the hypothetical period of time until Earth’s formation and earliest evidence of life).
“Knowing the total number of impact events on Earth during that 800 million year period is critical for panspermia, because the higher the number of impact events with interstellar objects during that period, the higher the probability of panspermia.” This is because it means that.
“In short, the physical properties of the interstellar ‘Oumuamua allow us to create a mathematical model that determines the authenticity of panspermia.”
In addition to a mathematical model that takes into account the physics behind panspermia: number density, mass density, total impact events, etc., Cao and his colleagues biological model This represents the minimum object size necessary to protect extremophiles from astrophysical phenomena (supernovae, gamma-ray bursts, large asteroid impacts, passing stars, etc.).
As discussed in the previous article, according to recent research, Cosmic rays erode all but the highest ISO before reaching another star system.
These additional considerations ultimately influence the number of celestial bodies (those not sterilized by astrophysical sources) that impact Earth and the plausibility of panspermia.
“To derive the minimum object size, we applied a variety of models, including the sphere-packing method, which roughly estimates the distance from the ejecta to the nearest supernova progenitor. (using Orion A), the gamma rays that reach that ejecta, and the attenuation coefficient (the amount of radiation that the ejecta absorbs) based on the most likely chemical composition of the ejecta (water ice),” Cao said. Stated.
Using a combination of physical and biological models, the researchers came up with an estimate of the number of ejecta that hit Earth before life arose. According to the earliest fossil evidence (from Archean rocks) found in western Australia, the earliest forms of life appeared around 1950. 3.5 billion years ago. Cao Cao said:
“We conclude that the maximum probability that panspermia gave rise to life on Earth is on the order of 10-5, or 0.001 percent. Although this probability seems low, under the most optimistic conditions So there could be a total of 4 x 109 habitable zone exoplanets, and our galaxy could exhibit a total of 104 habitable worlds with life.
“Furthermore, although we limited our analysis to the first 800 million years of Earth’s history, before the earliest fossilized evidence of life, life can seed at any point in a planet’s life. Because the habitable lifespans of planets are quite long (up to 5 years – 10 billion years), we have increased our estimate of the total number of habitable worlds with life in our galaxy by an order of magnitude. ”
From this, Cao and his colleagues came up with about 105 potentially habitable planets in the galaxy. However, these estimates are based on the most optimistic predictions of the planet’s habitability.
In other words, it assumes that all Earth-sized rocky planets orbiting within the habitable zone are capable of supporting life. That means they have thick atmospheres, magnetic fields, liquid water on their surfaces, and all life-bearing ejecta that survives entry into the atmosphere. Microorganisms may adhere to the surface.
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As Cao summarized, their results neither prove panspermia nor settle the debate about the origin of life on Earth. Nevertheless, they provide valuable insights and constraints on the possibility that life came here via objects like ‘Oumuamua.
Either way, these discoveries could have significant implications for astrobiology, an increasingly diverse field.
“Research on panspermia, the origin of life, incorporates physics, biology, and chemistry, but it is rare to find such a diverse range of themes in one research field. Astrobiology is more interdisciplinary. I think it’s a positive trend because it allows experts from all backgrounds to advance astrobiology.
“Our research could contribute to this trend. As for our findings regarding panspermia, it is unlikely that panspermia gave rise to life on Earth, but it is possible that it could lead to life in our galaxy. The number of habitable zone planets inhabited is quite large.”
“Future astrobiology research may use these findings to build on our work on panspermia. However, we are concerned about the It does not incorporate or even know all the factors.
“We believe our findings open new research areas to build on future panspermia research by updating models and incorporating additional elements.
“One potential area of research should we find evidence of life on other worlds in the future, whether in our solar system or through biosignatures in exoplanet atmospheres, is the potential for life to arrive via the panspermia mechanism. , to consider experimental and observational tests to distinguish life arrived at by the panspermia mechanism from life that evolved and arose on its own.”
This article was first published today’s universe.read original article.