How could life appear on earth?

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

Last week, Japanese scientists reported that during the experiment, a colony of deinococcus bacteria spent three years in outer space and survived. This indirectly proves that microorganisms are able to travel from planet to planet together with comets or asteroids and populate the most distant corners of the Universe. This means that life could get to Earth in this way.

Interplanetary wanderers

In 2008, researchers from the University of Tokyo (Japan), studying the lower layers of the stratosphere, found the bacteria Deinococcus at an altitude of 12 kilometers. There were several colonies of billions of microorganisms. That is, they multiplied even in conditions of powerful solar radiation.

Subsequently, scientists tested them for endurance several times. But neither the sudden changes in temperature - from minus 80 to plus 80 degrees Celsius in 90 minutes, nor strong radiation did not damage the persistent bacteria.

The final test was open space. In 2015, dried Deinococcus units were placed on the outer panels of the International Space Station's Kibo experimental module. Samples of various thicknesses spent one, two and three years there.

As a result, bacteria died in all aggregates thinner than 0.5 mm, and in large samples - only in the upper layer. Microorganisms in the depths of the colony survived.

According to the calculations of the authors of the work, bacteria in a granule with a thickness of more than 0.5 millimeters can exist on the surface of a spacecraft from 15 to 45 years. A typical colony of Deinococcus, about a millimeter in diameter, will last eight years in outer space. In the case of at least partial protection - for example, if you cover the colony with a stone - the term is increased to ten years.

This is more than enough for a flight from Earth to Mars or vice versa. Consequently, interplanetary travel of living organisms on comets and asteroids is quite real. And this is a strong argument in favor of the panspermia hypothesis, which also assumes that life came to Earth from space.

Inosystem guest

In 2017, the Pan-STARRS1 panoramic imaging telescope and rapid response system in Hawaii recorded an unusual space body. It was mistaken for a comet, but then reclassified as an asteroid, since no signs of cometary activity were found. We are talking about Oumuamua - the first interstellar object to arrive in the solar system.

A few months later, researchers at the Harvard-Smithsonian Center for Astrophysics (USA) showed that such interstellar bodies could be trapped in the solar system due to the gravity of Jupiter and the Sun. It is estimated that thousands of extrasolar asteroids are already flying around our star, potentially capable of bringing us life from another planetary system.

Most likely, such gravitational traps occur in most stars in the planetary system of which there are gas giants, the researchers note. And some, like Alpha Centauri A and B, can even capture free-flying planets that have left orbit around the parent star. This means that the interstellar and intergalactic exchange of life components - microorganisms and chemical precursors - is quite real.

It all depends on a number of factors. First of all, it is the speed and size of the potential carrier of bacteria and their survival. According to the model built by the researchers, such seeds of life from every inhabited planet spread through space in all directions. When faced with a planet with suitable conditions, they bring microorganisms onto it. Those, in turn, can gain a foothold in a new place and begin the process of evolutionary development.

Therefore, it is possible that traces of living organisms will be found in the atmosphere of exoplanets closest to the Earth in the future.

Life-giving meteorites

According to Canadian and German researchers, life on Earth originated from meteorites. Most likely, 4, 5-3, 7 billion years ago, these cosmic bodies bombarded the planet and brought with them the building blocks of life - the four bases of RNA.

By this time, the Earth has already cooled down enough for stable warm water bodies to form on it. When a lot of scattered RNA fragments got into the water, they began to stick together into nucleotides. This was facilitated by a combination of wet and relatively dry conditions - after all, the depth of these ponds was constantly changing due to the changing cycles of sedimentation, evaporation and drainage.

As a result, self-replicating RNA molecules were formed from different particles, which subsequently evolved into DNA. And those, in turn, laid the foundation for real life.

According to Scottish researchers, this is not meteorite meteorite, but cosmic dust. However, experts note: although it could contain the necessary building blocks, they most likely were not enough to form an RNA molecule.