What will we ultimately find on Mars?
This is another hot topic among astronomers these days, especially with what has been discovered by all of the probes that NASA has sent there.
You don't have to go back that far to the time when humans thought that Mars was a planet with Martians. Think of H.G. Wells' War of the Worlds and Ray Bradbury's Martian Chronicles. This was an idea promulgated by the astronomer Giovanni Schiaparelli when he supposedly discovering canals on Mars. Actually, he called them canali in Italian, which means channels or grooves, but the press translated it into canals, a suggestion that they were waterworks. Subsequent observations proved his canals were illusions. I can attest to the fact that astronomical observation of Mars is difficult even when it's in opposition (closest approach to Earth). It looks like a reddish ball with white spots on the top and bottom. The reason it's so hard to make out anything is that it's smaller than Earth and 40 million miles away at the closest.
So, what have we found on Mars? The answer is a supposedly dead planet with a very thin carbon dioxide atmosphere and no signs of water except that which is frozen at the poles. NASA has said that they see evidence in the topography of Mars that suggests that it once had liquid water on the surface, which would suggest that it had a better atmosphere. The theory is that Mars was once like Earth, had life, and this life in the form of bacterial found its way to Earth from a meteor collision. The large object knocked a lot of Mars out into space and if wondered into Earth orbit where it eventually fell to the surface.
The reason why Mars doesn't have much of an atmosphere and no liquid water is because the planet lost its magnetic field and the solar wind blew the atmosphere away, causing the water to evaporate into space. The reason Mar's magnetosphere went away is because it's molten iron core solidified. Keep in mind that Mars has a radius only slightly more than half that of Earth. The surface gravity is only 0.37 that of Earth.
What have all those probes to Mars discovered? Mars soil is called regolith, and is mostly igneous basalt, a volcanic rock that contains a lot of silica and iron oxide, which gives it the reddish color. This varies depending where one looks. The soil does contain water but it's locked up in compounds, such as hydrated calcium sulfate, and would be hard to get at.
The permanent polar caps contain frozen water and solid carbon dioxide. Each polar cap contains an estimated 1.6 million cubic kilometers of ice, so there is plenty of water, and some scientists suggest that there is frozen water beneath Mar's surface.
The more important question is: is there life on Mars?
First evidence: A meteorite found in Antarctica has structures that suggested the presence of remains of fossilized bacteria. This find has been criticized.
Second evidence: Curiosity found a rock that contains sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon, elements needed for life. The probe also found minerals that contained relatively fresh water, and later found organic matter in the form of chloro-methanes (methyl chloride). This isn't direct evidence for life, but it sure points to its possibility. At least all of the things needed for it are present on Mars.
Third evidence: This must wait until humans actually go to Mars. Life there won't be easy because Mars has neither a magnetic field nor an atmosphere to protect against the sun's radiation. Since Mar's atmosphere contains no oxygen, that will have to be either generated from the soil or formed from water by electrolysis. The pressure of the atmosphere is extremely low and the temperature is very cold necessitating a space suit.
The theory is that life formed on Mars before Earth and was transported to Earth in a meteorite. So, that means that we're Martians. All we had to do was look at ourselves to see Martians.
Thanks for reading.