The Phoenix lander returned data showing Martian soil to be slightly alkaline and containing elements such as magnesium, sodium, potassium and chlorides such as Sodium Chloride or natural salt. These nutrients are found in gardens on Earth, and are necessary for growth of plants. Experiments performed by the Lander showed that the Martian soil has a basic pH of 8.3, and may contain traces of the salt perchlorate. Perchlorates are found in dry arid regions or in deserts this does not mean these chemicals are detrimental to life like NASA would like us to think.
Silicon Map of Mars
Evidence suggests that the planet was once significantly more habitable than it is today, and in all probability, living organisms once lived there and still do. The Viking probes of the mid-1970s carried experiments designed to detect microorganisms in Martian soil at their respective landing sites and had positive results, including a temporary increase of Carbon Dioxide production on exposure to water and nutrients. This sign of life was later disputed by some scientists (as usual), resulting in a continuing debate, with NASA scientist Gilbert Levin asserting that, Viking may have found life. A NASA re-analysis of the Viking data, in light of modern knowledge of extremophile forms of life, has suggested that the Viking tests were not sophisticated enough to detect these forms of life (and that is debatable). The tests could, however, have killed a life form.
Martian Meteorite ALH84001
At the Johnson space center lab, some fascinating shapes have been found in the Martian meteorite ALH84001. Some scientists propose that these familiar looking shapes could be fossilized microbes extant on Mars before the meteorite was blasted into space by a meteor strike and sent on a 15 million-year voyage to Earth. But no one knows the meteorite’s point of origin on Mars. Small quantities of methane and formaldehyde were recently detected by Mars orbiters, which indicates there is life on Mars. In conclusion this meteorite contains the fossilized remains of simple life forms that once lived on Mars.
Scientists think that the most abundant chemical elements in the Martian crust, besides silicon and oxygen, are iron, magnesium, aluminum, and calcium. These elements are major components of the minerals comprising igneous rocks. Hydrogen is present as water ice and in hydrated minerals. Carbon occurs as carbon dioxide in the atmosphere and sometimes as dry ice at the poles. An unknown amount of carbon is also stored in carbonates. Molecular nitrogen makes up 2.7 percent of the atmosphere. As far as we know today, organic compounds are present because of the methane detected in the atmosphere. That living organisms that live there today have went underground because of the changes that have occurred to the planet's atmosphere (there also seems to be some evidence that a few of these life forms have been seen on the surface of Mars occasionally).
The elemental composition of Mars is different from Earth's in several significant ways. First, Martian meteorite analysis suggests that the planet’s mantle is about twice as rich in iron as the Earth’s mantle. Second, its core is richer in sulfur. Third, the Martian mantle is richer in potassium and phosphorus than Earth’s, and fourth, the Martian crust contains a higher percentage of volatile elements such as sulfur and chlorine than the Earth's crust does. Many of these conclusions are supported by in situ analyses of rocks and soils on the Martian surface performed by the Martian rover still in operation there.
Mars Topographical Map
Mars Orbital Laser Altimeter (MOLA) colorized shaded-relief maps showing elevations in the western and eastern hemispheres of Mars. (Left): The western hemisphere is dominated by the Tharsis Bulge region (red and brown). Tall volcanoes appear white. Valles Marineris (blue) is the long gash-like feature to the right. (Right): Eastern hemisphere shows the cratered highlands (yellow to red) with the Hellas basin (deep blue/purple) at lower left. The Elysium province is at the upper right edge. Areas north of the dichotomy boundary appear as shades of blue on both maps. This dichotomy boundary was the shores of a huge ocean in the northern hemisphere of Mars.
The Northern Ocean on Mars
The northern and southern hemispheres of Mars are strikingly different from each other in topography. This dichotomy (division) is a fundamental global geologic feature of the planet. Simply stated, the northern part of the planet is an enormous topographic depression that was once a huge ocean. About one-third of the planet’s surface (mostly in the northern hemisphere) lies 3–6 km lower in elevation than the southern two-thirds indicating it was the basin of this ocean. The dichotomy is also different in two other ways: as a difference in impact crater density and crustal thickness between the two hemispheres.
Mars Plate Tectonics
Besides the volcanoes in and around the Tharsis Bulge, there is other evidence of plate tectonics on Mars. The Mars Global Surveyor (MGS) discovered magnetic stripes in the crust of Mars, especially in the Phaethontis and Eridania quadrangles. The magnetometer on MGS discovered 100 km wide stripes of magnetized crust running roughly parallel for up to 2000 km. These stripes alternate in polarity with the north magnetic pole of one pointing up from the surface and the south magnetic pole of the next pointing down. When similar stripes were discovered on Earth in the 1960s, they were taken as evidence of plate tectonics. However, there are some differences, between the magnetic stripes on Earth and those on Mars. The Martian stripes are wider, much more strongly magnetized, and do not appear to spread out from a middle crustal spreading zone. Because the area with the magnetic stripes is about 4 billion years old, it is possible that the global magnetic field probably lasted for two or three billion years of Mars' life. At that time, the temperature of the molten iron in the planet's core should have been high enough to mix it into a magnetic dynamo that would have produced Mars’ magnetic field. This would have been necessary to protect the planet’s atmosphere from being ripped away by the stellar wind and prevent harmful radiation from reaching the planet’s surface.
A Banded Magnetic Rock