How far and quickly can dust particles spread life throughout the Universe
According to some studies, life can spread throughout the Universe with the help of cosmic dust. Scientists have long found out that life arose on Earth approximately 3.5 billion years ago. Research also confirms the presence of primitive life on Earth just 500 million years after its formation. However, the question of whether life arose spontaneously at the earliest stage of the Earth remains open.
New research conducted by Z.N. Osmanov, a teacher at the Faculty of Physics at the Free University of Tbilisi, is considering the possibility of panspermia – propagation of life through cosmic dust. This idea is not new, but Osmanov in his work suggests assessing how quickly this method of life transfer could have spread.
A study entitled «Possibility of panspermia in deep space using planetary dust grains» includes analysis that some dust particles can escape the gravity of their planet and travel outside the star system under the influence of radiation pressure.
The idea that life itself could travel through space on comets and ??asteroids has been around for a long time. It is believed that when these objects collide with planets, life can arise on them. However, for space dust to carry life, it must come from a planet that has life, and this can happen under certain circumstances. Research shows that dust particles from Earth in the upper atmosphere can mix with cosmic dust particles. Thus, one of the 2017 works showed that cosmic dust can interact with terrestrial dust, and a small part of planetary dust particles can be accelerated enough to escape the planet's gravity.
Freed from the gravitational grip of the planet, the dust is influenced by the pressure of stellar radiation. Scientists suggest that if a similar process occurs in other stellar systems, then particles of planetary dust can leave their system under the influence of radiation pressure, spreading life throughout the Universe.
However, life, being on specks of dust in interstellar space, must be very hardy in order to survive in the harsh conditions of space. Complex molecules or organisms, the precursors of life, must withstand the effects of radiation and other negative factors.
It is also important how quickly dust particles can spread life. Osmanov points out that in 5 billion years, dust particles can reach 10^5 star systems. According to the statistical approach and the Drake equation, the entire galaxy will eventually be filled with planetary dust particles. From this we can assume the existence of a huge number of planets with primitive life.
Osmanov refers to studies of panspermia and how it can occur in the vicinity of our galaxy: «In particular, it is noted that due to the pressure of solar radiation, small dust grains containing living organisms can reach the nearest solar system within nine thousand years & ;mdash; Alpha Centauri». Modern powerful rockets such as the Space Launch System and Falcon Heavy would take more than 100,000 years to complete such a journey.
Osmanov calculated that a significant number of dust grains would survive interstellar travel, preserving life or complex molecules: «It is natural to assume that the number of planets with primitive life should be enormous». This may be a natural assumption, but there is little evidence for its truth. Using a statistical approach to the Drake equation, Osmanov writes that the number of planets on which life arose “should be on the order of 3×10^7».
«This value is so huge that if dust particles can travel a distance of several hundred light years, then we can conclude that a space with a diameter of 100,000 light years must be full of complex molecules» — explains Osmanov. However, as the author notes, it is still unknown how life appears and how widespread it is throughout the Universe. There are many variables, studying these processes is difficult, and at the moment there is not enough convincing evidence for the existence of any organisms on other planets.
One can only imagine how far and how quickly life can spread. But to make progress in understanding these processes, further research and empirical data are required to better understand the nature of life and its ability to spread throughout the Universe.