Origin of life on Earth | Panspermia theory | Origin of life-1

The most mysterious question in human's history is "how life began on earth". 20% of the scientists believe that the life on Earth is actually originated in space.

How did the life came from space?

To know about this in detail, we must know about the Panspermia theory.

Panspermia
By Silver Spoon Sokpop - Own work; For the proto-bacteria I used an adapted version of File:Bacteria-.svg by JrPol and for the DNA I used an adapted version of File:DNA chemical structure.svg by Madprime. Earth from File:Earth Flag.svg by Himasaram, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=8047074

According to Panspermia, the life on Earth is originated from microorganisms present in outer space and these microorganisms are carried by comets, asteroids, meteoroids etc.,

Panspermia is classified into several types based on different explanations and theories.

1. Radio Panspermia:

According to Radio Panspermia, microorganisms exists throughout the universe and these microorganisms travelled for a long time and reached planets due to the radiation pressure of stars. From this single cell organisms started to grow and after billions of years, they divided and converted into several life forms on Earth.

2. Litho Panspermia:

According to Litho Panspermia, one of the planet may have life on it, but due to asteroid impacts or volcanic eruptions, the microorganisms on that planet are carried into outer space by rocks and reach other planets.

But scientists believe, this theory is not the actual reason, because rocks need more that 20 GPa pressure to reach outer space by volcanic eruptions or asteroid impacts. From estimations, the biggest volcanic eruption on Earth is occurred on Sarusas in Brazil (130 million years ago). It released 1 GPa of pressure, which is not at all sufficient for the microorganisms to reach outer space.

3. Pseudo Panspermia:

According to Pseudo Panspermia, life originates from organic compounds like Amino acids, Nucleic acids etc., These organic compounds formed when the stars & planets were formed and these organic compounds are carried by asteroids, comets, meteoroids and reached Earth by impacts. Many scientists agree with this theory.

4. Extra-terrestrial life & directed Panspermia:

According to Extra-terrestrial & directed Panspermia, many intelligent life forms began on many planets after millions of years from big bang. These advanced civilizations started sprinkling the microorganisms over other planets and this caused the life to began on Earth. Some of the scientists agree with this theory.

Let's explore some of the proofs behind the theories:

• In December 1984, researchers found one meteorite in Antarctica. Researchers from NASA made some observations on it and concluded that it came from Mars. Researchers also noticed bacteria fossils in that meteorite. From Carbon dating, researchers also concluded that it came to Earth at about 13000 years ago. But bacteria fossils on it are 18000 years old, which means it contains bacteria before it reaching Earth. This evidence strengthens Panspermia theory.
• In 2001, two researchers from University of Naples studied one meteorite. They founded bacteria inside the meteorite and concluded that the bacteria is not from Earth.
• In 2001 & 2005, ISRO has done 2 experiments on air taken from Earth's atmosphere (20-80 kms height) and tested in laboratory. They founded 12 types of bacteria in which 3 types of bacteria are never seen before on Earth. They survived even from UV radiation, which means they can also survive in space.
• In ISS, Russian Cosmonauts noticed bacteria on metal outside the ISS. Everyone got a doubt that how can bacteria be formed and survived in space.

EURECA_deployment
Image credit: NASA

Space programs like Exobiology Radiation Assembly, Biosatellites, Tanpopo etc., were specifically designed to do research on existence of life in space. These missions take microorganisms from Earth and do research on them in space. Astonishingly some of them were surviving.

Many asteroids and comets contains water, ice & Amino acids on the surface. So, these strong evidences made us to believe that life also exist in outer space. Panspermia theory have some evidences to show life exist in outer space, but we don't know the exact reason behind the origin of life on Earth.

If we think the Panspermia is right, then the extra-terrestrial life also exists because every star system has asteroids, comets and other building blocks to began life.

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