According to the hypothesis of Panspermia, life exists through the universe, and is dispersed among planets, stars and even planetary systems by comets, meteors and planetoids. In this regard, life started on Earth around 4 billion years prior after microorganisms on a meteor hit the earth. Throughout the years, many scientists have been dedicated towards showing that the different parts of this hypothesis function.

The most recent one is from the University of Edinburgh, where Professor Arjun Berera presents different way for the movement of life-bearing molecules. In his current research, he claims that space dust that occasionally comes into contact with Earth’s atmosphere could be what transported life to our planet billions of years ago. According to this, life could be spread all over the galaxy in this way.

For his research, which was lately released in Astrobiology titled “Space Dust Collisions as a Planetary Escape Mechanism”, Prof. Berera analyzed the likelihood that spaced dust could help the escape of molecules from Earth. These incorporate atoms that show the existence of life on Earth (otherwise known as. biosignatures), as well as microbial life and atoms that are vital to life.

The theory of Panspermia states that life is distributed throughout the Universe by microbes traveling on objects between star system. Credit: NASA/Jenny Mottor

Space dust effect hit Earth’s atmosphere all the time, at a daily rate of around 100,000 kg (110 tons). The dust has mass from 10-18 to 1 gram, and can travel with up to 10 to 70 km/s (6.21 to 43.49 mps). Accordingly, it can hit Earth with sufficient force to hit atoms out of the atmosphere and into space.

They would comprise to a great extent of those that are available in the thermosphere. At this level, those molecules would comprise mostly of chemically disassociated elements, for example, molecular nitrogen and oxygen. However, even at this height, there are also bigger particles –like the ones that could contain microscopic organisms or organic molecules. As Dr. Berera states in his research:

Molecules that comprise the thermosphere or higher or get there from the ground, if they clash with this space dust, they can be dislocated, changed in form or taken by incoming space dust. This could affect weather and wind, but most fascinating is the probability that such clashes can give molecules in the atmosphere the required escape speed to get away from Earth’s gravity.

But, escaping from our atmosphere is not that easy. First of all, it is necessary that there be enough upward force that cans speed up these molecules to escape speed rate. Then, if they are sped up from insufficient height (i.e. in the stratosphere or below), the atmospheric density will be sufficiently big to slow down the escaping particles.

Photo of an aurora taken by astronaut Doug Wheelock from the International Space Station on July 25th, 2010. Credit: Image Science & Analysis Laboratory, NASA Johnson Space Center

Furthermore, because of their fast upward movement, these molecules would endure huge warming to the point of vaporization. So while wind, lighting, volcanoes, and so forth could create great forces at lower heights, they could not speed up particles as to reach escape speed. However, in the upper levels of the mesosphere and thermosphere, molecules would not endure much drag or warming.

All things considered, Berera infers that only molecules and atoms in the higher atmosphere could be pushed into space by space dust clashes. First they are flung into the lower thermosphere or higher in some way and after that pushed much harder by fast space dust clashing.

Berera inferred that particles that are at a height of 150 km (93 mi) or higher over Earth’s surface would be hurled above the Earth’s gravity. Then they would be in space close Earth, where they could be taken by passing astronomical objects, for example, comets, space rock or other Near-Earth Objects (NEO) and transported to other planets.

But then we would have to ask if these life forms could survive in space. However, according to Berera, earlier researches have proven the probability of microorganisms to survive in space. Such are bacterial spores which left outside the International Space Station at height ~400km have survived 1.5 years.

The tiny Tardigrade (aka. “water bear”), which could be the toughest creature on Earth. Credit: Katexic Publications, unaltered, CC2.0)

There is also the unusual case of tardigrades, micro -creatures with eight-legs called “water bears”. Earlier tests have demonstrated that they can survive in space, and are resistant s to radiation and lack of water. Thus it is likely that such creatures, if they were chased out of Earth’s upper atmosphere, could survive sufficiently long to reach another planet with some astronomical object.

Finally, according to these discoveries big space rock hits might not be the main transport means of life between planets, as defenders of Panspermia believed. It is likely that microorganisms that have fled from Earth’s atmosphere have been transported and survive on other planets.


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