Mars

Statistics: 

 History of Observations
 Moons of Mars
 Robotic Exploration
 Life on Mars?
 Human Mars Missions?
 

History of Observations:

Mars has long been an object of interest and fascination to both scientists and non-scientists.  The bloody, reddish appearance of Mars in the night sky led the Romans to name it for their god of war.  In recent times (since the 19th century), the planet Mars has become a place of ever-increasing awe and speculation for the inhabitants of the Earth.  In 1877, the Italian astronomer Giovanni Schiaparelli made public the results of a numerous series of telescopic observations that he'd made of the Red Planet for quite some time.  One of the most interesting observations that Schiaparelli reported was that he had seen what he called canali criss-crossing the surface of the planet.  These canali were incorrectly translated to be Martian "canals"* that were reported by many scientists earlier this century to have been constructed by intelligent life forms on Mars.
 

 
Comparison of Early and Modern Observations of Mars
 
There were many debates about the exact nature of the "canals".  Finally, upon closer examination of the Martian surface with better telescopic instruments it was determined that the Martian canals did not really exist; they were, in fact, no more than an optical illusion.  The trick is that the human eye would notice features on the surface of Mars and the viewer's mind would unconsciously connect these features into a pattern.  For example, look at the following figure:  there are two green circles that appear to have a black bar laying atop them; however, do you actually see the black bar between the two circles?  Of course you don't because there is no black bar, it just appears that there is one.  This is the same type of illusion that fooled many of the early observers of Mars into thinking that canals existed on the surface of the Red Planet.
 

Another such optical illusion that plagues the surface of Mars is the so-called Face on Mars.  At first glance, the feature on the surface really does look like a huge human face.  This has led some people to speculate that there was (or is still) a race of intelligent creatures living on Mars trying to communicate with Earthlings; another popular theory is that an advanced race of humans (or near-humans) existed at one time on Mars.  The "Face" is really a rock formation that happened to be caught in just the right light so that it's shadows were projected in such a manner so as to suggest that the feature appears very face-like.  This is the same optical illusion that makes people think that they're seeing familiar objects (such as faces, bugs, and cars) in cloud formations.
 

 
Martian Moons:

Mars is the only other inner planet to have moons besides the Earth.  However, unlike our own moon, the moons of Mars are extremely small.  They are called Phobos and Deimos, named for the companions of Ares, the Greek god of war.  Phobos and Deimos are very small for moons, with Phobos being 27 kilometers across and Deimos being only 15 kilometers across.  They are so small that they're gravitational fields are not strong enough to pull them into a spherical shape.  Some scientists think that these Martian moons are no more than unfortunate asteroids that strayed too close to Mars and got snatched up by Mars' gravity.
 

 
The Moons of Mars:  Phobos (left) and Deimos (right)

Robotic Missions to Mars:

Among the most successful of robotic planetary exploration missions were those of Vikings 1 & 2, which were both launched in the summer of 1976.  The Viking probes consisted of two primary pieces:  an orbiter and a lander.  The Viking landers separated from the orbiters upon arrival at the Red Planet, and the landers then descended onto the Martian surface, each at a different location on the planet's surface.  Among some of the discoveries of the orbiters were that Mars had numerous features of geologic interest.  Some of these included volcanoes as high as 15 miles, vast canyons the size of the continental United States, and northern & southern poles composed of carbon dioxide and water ice!  However, perhaps the most interesting discovery made by the orbiters was that the Martian surface bears many signs of once having had liquid water flowing there!  Here are some images to back up this claim...
 

  
 
This evidence for great amounts of liquid water having once flowed over the Martian surface has lead to many questions as to whether or not there once existed (or still exists) any life on Mars.

In addition to the geologic features, the Viking orbiters also discovered that the Martian atmosphere, though very thin and cold, is very active.  Numerous dust storms were photographed over a period of years; it was also determined that these Martian dust storms are seasonal in nature.

On July 20, 1976 the first Viking lander set down on the surface of Mars in a flat plain known as Chryse.  Shortly afterwards, the first images of Mars as seen from it's surface were returned to Earth.
 

 
Views from the Viking 1 and 2 Landing Sites
 
The object in the lower right-hand corner of the image is the landing pad of the Viking 1 lander.  It was revealed by the landers that the Martian surface is very much like some of the more remote deserts of Earth... it is a dry, rocky, cold, and barren place.  The atmospheric pressure at the surface of Mars is a measly one percent that of atmospheric pressure on the Earth.

A more recent mission to Mars, the Mars Pathfinder mission, set down a lander and remote control rover on the surface of Mars on July 4th, 1997.  Since that time, the Mars Pathfinder lander and rover have gathered a wealth of information concerning the chemical and geologic makeup of Mars.  For more information on this most recent mission to the Red Planet, click here.

Life on Mars?

One of the goals of the Viking missions was to determine whether or not there existed life on Mars.  Each Viking lander was equipped with a shovel-like device that would scoop up a sample of the Martian soil; the soil was then deposited into an on-board laboratory that performed three experiments that would hopefully determine if any life forms inhabited the Martian soil.  The results of the experiments were proposed by NASA scientists to have been inconclusive at best.  Thus, the hope that Earthlings may have had neighbors inhabiting a nearby planet seem to have been dashed; however, in the last few years, hopes have been renewed that there might have existed (or still exists) microscopic life forms on Mars.

In 1984, scientists uncovered a meteorite in Antarctica that has been determined to have originated from Mars.  Researchers claim to have discovered bacteria-like structures within the Martian meteorite.  However, there is still much debate in the scientific community as to whether or not these structures are really ancient Martians or just the geologic results of exotic chemical reactions within the Martian crust.
 

Ancient Martian Bacteria???
 
For more information on the discovery and analysis of the Martian meteorite, check out the following web page that was assembled at Purdue's astronomy website.  This link also provides more links to more detailed and technical information on this potentially amazing discovery.

Human Missions to Mars?

Of all of the planets that occupy our Solar system, Mars is the most Earth-like of them all.  The Martian day is just barely over that of an Earth day, Mars undergoes seasonal changes very similar to Earth's (though longer in scope), and Mars is the only planet besides Earth that exhibits signs of liquid water.  These factors and the proximity of Mars to Earth (comparatively speaking, Mars is easy to get to) make Mars an ideal prospect for exploration by human hands.

NASA has accepted a plan to place humans on the surface of Mars within the next 20 to 25 years.  It is hoped by some that these missions could eventually lead to the human colonization of the Red Planet.  Some scientists look at Mars as the cosmic stepping stone that will make the human race a truly space-faring civilization.  For more information on the plan to have humans explore Mars, check out Robert Zubrin's "Mars Direct" website.


*Reference William Sheehan's work for more information on early explorations of Mars.

 
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-- M. Lowry, 12-16-97