Scientists would have to search underneath the surface of Mars if they want to find any sign of life. All Mars explorations have always searched signs of life on its surface, in areas that contain remnants of bodies of water. Until now, there is still no evidence of life in any of them, but there could be abundant Martial microbes gathering underground.
Decades of study have proven the existence of a deep biosphere on Earth. This deep biosphere is an environment rich in microorganisms. Scientists speculate that the same zone thrives underneath Martian soil.
It is known that billions of years ago, the surface of Mars was similar to that of Earth’s. Yet it transformed dramatically when it was exposed to a bombardment of intense radiation. This would have made living on Mars’ surface very difficult.
The subsurface of Mars is a promising section for those who want to search for alien microbes. It is far more habitable than the deep biosphere of the Earth. The more porous subsurface rocks create pockets for gas exchange and nutrients. The core of Mars, even if it’s molten, gives a more favorable temperature for microscopic organisms that live in deep parts of soil and rock.