Mars has inspired our imagination over the centuries, and has been the
focus of intense scientific interest for many years. Mars has shown itself
to be the most Earth-like of all the planets; it has polar ice caps that
grow and recede with the change of seasons, and markings that appear to
be similar to water channels on Earth. It is a small rocky planet that
developed relatively close to the Sun and has been subjected to some of
the same planetary processes associated with the formation of the other
"terrestrial" planets like Mercury, Venus, and Earth. Martian
tectonics-the formation and change of a planet's crust--differs from Earth's.
Where Earth tectonics involve sliding plates that grind against each other
or spread apart in the seafloors, Martian tectonics seem to be vertical,
with hot lava pushing upwards through the crust to the surface. Mars has
some remarkable geological characteristics including: the largest volcanic
mountain in the solar system, Olympus Mons (27 km high and 600 km across).
Volcanoes in the northern Tharsis region are so huge they deformed the
planet's shape. There is also a gigantic equatorial rift valley called
the Vallis Marineris which is a canyon system that stretches a distance
equivalent to the distance from New York to Los Angeles.
The average temperature at
surface of Mars is approximately -86oC to -5oC and the atmosphere is
composed primarily of carbon dioxide, nitrogen, and argon. From this we
find that Mars' atmosphere is now too thin and its temperature too cold
to allow liquid water. However, Mars certainly had surface water and groundwater
once; liquid water shaped the valley networks in the highlands and the
huge flood channels that cut from the highlands to the northern lowlands.
How much water was there? Estimates range from the equivalent of an ocean
10 meters deep covering the entire surface to the equivalent of a layer
kilometers deep. Where did the water go? It could be underground in pools
of groundwater, either small or huge depending on how much water Mars
started with. Or it could have escaped to space and been lost completely
- the hydrogen from water can escape easily through Mars's low gravity
and small magnetic field.
A huge deposit of the mineral hematite extends over 300 miles on the rocky
planet. It has led to speculation that there was water on Mars long enough
for life to form. The hematite mineral deposit "is really the first
evidence we have that hot water was around long enough for a geological
period of time so that potentially life could have had an opportunity
to form," said Arizona State University Prof. Phil Christensen. Hematite
is an iron oxide mineral that forms by a variety of ways that often involve
water. The coarse-grained hematite spotted on Mars occurs on Earth around
volcanic regions such as Yellowstone National Park. It is evidence that
a large-scale hydrothermal system may have operated beneath the Martian
surface. Why is this important? "If you want to find out about possible
life on Mars, the deposit is a good place to start," Christensen
said. "You've got water, you've got heat, got energy."
In April new information was discovered about the planet's north polar
cap and its surrounding features, including dune fields that share similar
properties to North Africa's sand dunes. The presence of high altitude
clouds above the polar cap was also revealed. During the winter, the polar
cap was noted as expanding. This suggests that liquid water may or may
not be present at certain times of the Martian year.
In addition, a new composite photograph of a crater 25 miles wide and
1 to 1½ miles deep about 3,600 miles south of the Martian equator
has been released to the public. The deep, dark area near the middle of
the crater appeared to be a frozen pond and there was evidence of water
seepage as well. All of this evidence of water and mineral deposits comes
into play in our search for answers concerning the mysterious planet Mars.