How likely is it that life on Mars could prove deadly to our explorers? What should we worry about and how would we recognize non-terrestrial life? This lesson is written during a strange time for our planet… A microscopic replicating piece of bio machinery is rapidly killing some of the human inhabitants of the earth… Well over a million of our fellow Homo sapiens have perished… How is this possible? How can something incapable of any independent life cause so much death… And what are the possibilities for life on Mars? Let’s go from technology to biology for a minute today…because…when you get to Mars…you’ll need to know what to watch for…you could be the first person to find life off Earth… And if there is life…how much of a threat will it be to our explorers. Mars was once a very hospitable place for life… It is farther from the sun than the Earth…if we use the distance from the Earth to the sun as a measure, called an Astronomical Unit or AU then Mars is 1.5 AU from the sun… since we know that the power or flux of an energy source drops with the square of the distance then we should be able use the equation. Flux Mars = 1/1.5^2 or 1 / 2.25, which is 0.444 or 44.4%. The flux or energy from the sun, called the Luminosity is 3.9 x 10^26 Watts. The amount received at the orbit of the Earth is 1370 Watts/m^2. If we take our 44.4%, we get 608 W per square meter. This was still enough energy to allow for liquid water on the surface of Mars. Our orbital and rover evidence shows that Mars used to wet and warm. This time on Mars is called the Noachian Period and started between 4.1 and 3.7 billion years ago. Remember that our solar system is about 4.54 billion years old. The Earth at this time was going through its Hadean, just like it sounds basically, Hades…lava, carbon dioxide, methane and hydrogen, and later Archean eons. This is when we find evidence that life first rose on Earth. Life seems to have started almost as soon as the Earth cooled down enough for it to be possible and survived the late heavy bombardment…when asteroids disturbed from their orbits by the gas giants rearranging themselves from gravitational perturbations…but back to Mars… Mars was warm enough to have liquid water on its surface with oceans and lakes, weather and rain and lasted at least 400 million years…after that the core of Mars cooled, the magnetic field protecting it from the solar wind became too weak…and the atmosphere of Mars started to be stripped away… as the atmosphere became too thin to support liquid water it disappeared from the surface, surviving on the surface at the poles and as a type of permafrost in the ground… Life on Earth arose at least 3.77 billion years ago and perhaps as early as 4.28 billi ... https://www.youtube.com/watch?v=_1gexwigDDM