Panspermia

Panspermia comes from the Greek word panos, which means everything and sperm is a seed.
This hypothetical cause of life on Earth is called panspermia. It is believed that it is the cause of the “spores of life” – the simplest microorganisms that are in a “closed” state. Meteoroids and comet nuclei can act as “carriers” of spores, which are undoubtedly present not only in the Solar System, but also move in interstellar space from star to star. If the “spores of life” from outer space hit the Earth, they could lead to the development of the entire biosphere of the planet. However, this hypothesis does not yet have convincing evidence.
Technogenic panspermia requires the closest attention to itself.
This possibility takes place in two aspects: it is the possibility of “infection” by microorganisms of the atmosphere and surface of other planets of the Solar System from Earth, as well as Mars, where there are conditions for the existence of terrestrial life, when landing spacecraft on these bodies. There is also a danger that the simplest life existing there may die under the influence of our planet. And the fact is that, once on Earth, microorganisms can create completely unexpected and sometimes dangerous forms of living organisms in a relatively short period of time. In order to avoid such situations, all spacecraft that will be sent to space bodies whose conditions at least remotely resemble those on Earth are sterilized – chemical and radiation destruction of terrestrial microorganisms.
Thirdly, there is a risk to the Earth’s biosphere in the case of the delivery of soil samples from other space bodies. Despite the fact that biological life on the Moon is excluded by all indications, the most serious precautions were taken during the study of soil from the Moon to avoid direct contact of its samples with objects of terrestrial nature. These samples are still in sealed vessels, despite the fact that their absence of any life has been absolutely confirmed.