Mars | Research & Encyclopedia Articles

Mars

Before the invention of the telescope, Mars was just another of the "wanderers" that traveled through the sky. Its only distinguishing characteristic was its reddish color, which produced associations with war and fire. The Chaldeans called it Nergal, their god of the dead and battles. To the Persians it was the Celestial Warrior, and to the Greeks it was Ares, meaning "disaster" or "vengeance." The Romans named it Mars after their god of war.

The first drawings of Mars which show any surface features that correspond to real ones were made by Christiaan Huygens in 1659 and 1672. One sketch clearly shows Syrtis Major, while the Martian ice cap at the south pole is visible in another drawing.

Huygens was able to see such details with inferior telescopes because Earth and Mars are not always the same distance apart. Every twenty-six months Earth overtakes Mars in its orbit; especialy good viewing is possible during this time of opposition, as it is called. Huygens also established the period of rotation as nearly that of the Earth: 24 hours.

Another early observer, Giacomo Filippo Maraldi (1665-1729), also observed Mars closely during these oppositions. By 1702 he had determined the rotation of Mars to be closer to 24 hours and 39 minutes. He also noticed changes on Mars, but he wasn't sure if these were due to clouds or surface markings. In 1719 he discovered that the white polar regions did not coincide with the geographical poles of the planet. The ice caps of Mars are eccentricities to the poles, which is also true of the Earth. Interestingly, the polar eccentricities of Earth had not been discovered yet, so Maraldi learned something about another world that was not yet known about his own planet.

The late 1700s saw William Herschel turn his attention to Mars. He proposed that the white polar areas were really accumulations of snow and ice. He believed the planet had an atmosphere and, as a result, probably had conditions similar to the Earth. He was the first to notice color changes on Mars, and he also established the beginning of spring, and he measured the tilt of the axis. Herschel even came up with a more sophisticated measurement of the planet's rotation period: 24 hours, 39 minutes, and 21.67 seconds.

The opposition of 1877 brought a solution to one problem but created another. For years astronomers had been drawing Mars and christening features they saw with the names of astronomers. Therefore, it is easy to see how conflicts could arise: for example, English astronomers tended to use the names of fellow countrymen, as did the Italians, French and Germans. One man named no less than four major features after an astronomer from his own country. This tower of Babel was torn down when the Italian astronomer Giovanni Schiaparelli (1835-1910) discarded these names. Schiaparelli gave Latin names to all features, thus antagonizing no nation or individual. For example, the so-called Kaiser Sea became Syrtis Major.

In solving the issue of naming the features of Mars, however, Schiaparelli created another problem, however, for which Mars will be eternally famous. Schiaparelli made maps that showed lines connecting dark areas on the planet's surface. He called these lines canali, an Italian word that meant "grooves" or "channels." The second meaning reflected his belief that the markings were possibly natural connections between the dark areas, supposedly seas as they were thought of at the time. The problem came when the word canali was translated to "canal," which suggested artificial waterways. This issue prompted worldwide interest in Mars and sparked a flood of publications addressing Mars, many of which speculated on the implications of man-made canals on Mars. In 1892 a book appeared that described the struggle of Martian engineers to fight off the encroaching desert by using massive canals to transport water to the thirsty inhabitants. Schiaparelli drew the canals again in 1879. This time, they appeared straighter. He also discovered that some of his previously drawn canals now looked like they were really two separate ones: optical illusions seemed to be at work here. He showed a Mars with definite seasonal color changes: the dark areas grew darker during the Martian spring and lighter during the Martian winter. To his credit, Schiaparelli never pushed the idea that intelligent life had created the canals.

The most outspoken advocate of life on Mars being responsible for the canals was Percival Lowell (1855-1916). He founded an observatory in Flagstaff, Arizona, from which he made detailed observations of Mars. Lowell developed the idea that Mars was an old planet running low on atmosphere and water with an environment growing more hostile for its inhabitants. He believed the dark areas were vegetated lowlands surrounded by deserts of higher elevation. Others tried to explain the canals without reference to intelligent design. Some said the canals simply did not exist. Others said they were optical illusions caused by small dark spots on Mars that formed patterns, making the eye see lines where none existed. There were other explanations for the canals: they were natural waterways, they were strips of vegetation, they were natural cracks in the planet's surface.

The end to the canal controversy came after the American space probes Viking 1 and Viking 2 landed on Mars in 1976. They revealed a cratered planet with little oxygen, a lack of liquid water, and high ultraviolet radiation that could easily destroy microbes. They also sent back pictures and data indicating Mars is a barren, desolate world. The experiments on board could not completely rule out the possibility of life, but Mars appears as devoid of life as the Moon. The most interesting features are Olympus Mons, a huge inactive volcano some 15 miles (24 km) high, and Valles Marineris, a vast canyon stretching over 2,000 miles (3,218 km) in length. There are also what appear to be dried-up riverbeds and flash-flood channels, indicating that subsurface ice, melted by heat from occasional volcanic activity, comes to the surface and produces a brief flash flood as the water boils away due to the low atmospheric pressure.

Several unmanned missions were directed toward mars in the 1990s, as successors to the phenomenally successful Viking missions, but for a while the red planet seemed determined to keep its secrets. In 1992, NASA's billion-dollar Mars Observer was successfully launched, reached Mars in late August of 1993, and disappeared without a trace, never to be heard from again. The Russian-led Mars 96 mission, laden with a large number of complex experiments, did not even get on course for Marc, crashing unceremoniously into the Pacific Ocean in November 1996. Finally, two successful missions were launched. The Mars Global Surveyor lifted off shortly after the Mars 96 crash and reached Mars in September 1997, where it would perform exhaustive mapping of the Martian surface, as well as analysis of the planet's atmosphere and magnetic field. In July 1997, NASA's Mars Pathfinder mission landed on Mars and deployed the robot crawler Sojourner. Sojourner earned immediate fame as the first mobile craft to be delopyed on the surface of another planet. It studied the Martian soil and rocks, but returned no evidence of life.

The scientific community was rocked in 1996, when scientists announced that the Allan Hills meteorite, discovered in 1984 in Antarctica and determined to have originated on Mars, possibly contained evidence of formerly living organisms. A storm of debate arose, and some researchers published analyses indicating that the organic material in the meteorite actually originated on Earth, not Mars. As of mid-1998, the debate had not been resolved, and the question of whether Percival Lowell was right or wrong remained unanswered.