THE DAY THE NASA INTENDS TO ANNOUNCE
THAT
THERE IS A LIFE ON MARS
BY: IZAKOVIC
CREATED 12-28-2000
2. ARE SALTY
Generally speaking, Martian atmosphere contains 95 % carbon dioxide, 2,7 % nitrogen, 1,6 % argon, 0,2 % oxygen, and trace amounts of water vapor, carbon monoxide, and other noble gases.
It is said that the average atmospheric pressure at the surface is close to 0,006 bar, which is 0,6 % of that on Earth. Surface pressure fluctuates by about 30 % due to the seasonal cycle of the polar caps.
Surface temperatures vary with time of day, season, and latitude. Maximum summer temperatures may reach 17 ºC, but average daily temperatures at the surface do not exceed -33 °C. Due to the thinness of the atmosphere, daily temperature variations of 100 ° C are common. Above 50 °lat. temperatures remain cold enough (less than -123 °C) throughout winter for the atmosphere's major constituent, carbon dioxide, to freeze into the white deposits that make up the polar caps.
So far it would seem that Mars surface consists of rocks and sand, occasional water spouts, wet/ frosted crater bottoms, carbon dioxide polar caps, permafrost layers, and at least one lake.
As far as water spouts are concerned there were lots of them near the Mars southern pole, at 121.91°W and 85.25°S, in October 1999, when this image was taken.
Image t is tilted 27 º to the right as is the source image linked to it. Details part of much larger area of obviously fluvial character, showing innumerable water spouts in light Martian wind.
From the physics is known that, at average atmospheric pressure on the Earth's surface (1 bar), water saturated with diluted kitchen salt (NaCl) can have freezing point as low as -21 °C. If right ratio of calcium chloride salt (CaCl) is used, freezing point goes down to -55 °C. At lower atmospheric pressure, for example equal to that which is average on Mars (0,006 bar) water evaporates at 0,04 ºC.
Therefore, if water was present on Mars during long period of time, it is logical to presume that it has deeply penetrated every pore and cavity of the ground and that, over the time, has accumulated largest available content of various salts. Martian sea, as any other lowest level standing water or sea on any planet or moon, must have been rich with salts. Such water can remain liquid at very low temperature and still not evaporate at very low atmospheric pressure. Therefore the presence of liquid, salty water in the craters and canyons which are shielded form the Sun and whose upper surface is heated by the Sun could be expected.
That this is indeed the strong case indicates the latest discovery made by NASA's Galileo spacecraft whose data suggest that Jupiter's largest moon, Ganymede, may possess a huge salt-water ocean beneath its frozen, crusty surface. This information was announced by Margaret Kivelson of the University of California at Los Angeles on 16 December 2000, during the meeting of the American Geophysical Union held in SAN FRANCISCO.
However, there is a small problem with the above image.
The presence of all those geysers indicate that the heat, which is necessary to make and keep the water liquid and to build the pressure allowing the water to gush out of the ground, cannot be generated from the above, by the Sun irradiation. If this was the case than the surface should melt and evaporate first, especially if it consists of the frozen, easily volatile, and thermally low conductive carbon dioxide ice only. Although large part of polar cap evaporates during the Summer, it's water ice part always persists.
Little
is known about the interior of Mars. Planet's relatively low mean density and
absence of global magnetic field indicate that Mars cannot have an extensive
nor fluid metallic core. Judging from its ability to support such massive
topological features as Tharsis, the crust of Mars may be as thick as 200 km,
five to six times as thicker than that of Earth. In
geological sense it is, basically, a dead planet. Only perceivable internal heat
source of natural origin, which could generate heat energy in required
quantities could be that from the decoy of radioactive minerals on surface or
still hot rock in planet's interior. Considering so far available evidence of widespread liquid water
presence, Mars should be globally rather radioactive place.
To check on this the Mars Surveyor 2001 Orbiter is scheduled for launch on April 7, 2001. It will carry three instruments, the Thermal Emission Imaging System (THEMIS), the Gamma Ray Spectrometer (GRS), and the Mars Radiation Environment Experiment (MARIE).
According to the JPL, THEMIS will map the mineralogy and morphology of the Martian surface using a high-resolution camera and a thermal infrared imaging spectrometer. The GRS will achieve global mapping of the elemental composition of the surface and determine the abundance of hydrogen in the shallow subsurface. The GRS is a rebuild of the instrument lost with the Mars Observer mission. The MARIE will characterize aspects of the near-space radiation environment as related to the radiation-related risk to human explorers.
Full details of the Orbiter ant its mission are available at the JPL page linked to the above Orbiter image.
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All of the above images are the courtesy of NASA/ JPL/ Malin Space Science Systems.
file:
mars1.htm