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Mars Exploration: From Ancient Times to Present Day

The planet Mars has long fascinated mankind, and our view of the planet has changed greatly over time. Both the scientists’ and the populations’ knowledge of Mars has increased enormously due to years of study and exploration of the planet.

Mars has fascinated people since the ancient Babylonians, Romans, and Greeks noticed that some of stars were "wanderers" and moved relative to the background stars. Because the planets orbit the Sun and are much closer to us relative to the stars in our galaxy, we can see their movement around the Sun over time. As seen in the night sky, planets do not twinkle like stars do, because planets are very close compared to stars and the reflected sunlight coming from them is very bright. The stars that we can see from Earth are many trillions of miles away and, as their faint light enters our thick atmosphere, their light becomes distorted and "twinkles." The ancient people did not know that the stars were suns located very far away. They believed the wandering stars (planets) were "gods" and named them such. The distinct red color was observed by stargazers throughout history. The Romans gave Mars its name in honor of their god of war. Other civilizations have had similar names. The ancient Egyptians named the planet Her Descher meaning the red one.

In 1609, the Italian astronomer Galileo Galilei observed Mars with his primitive telescope. In 1610 he wrote a friend describing Mars as a "spherical body illuminated by the Sun." He noted that it went through phases like the Moon. It is believed that Galileo was the first person to use the newly invented spyglass to look at the heavens. He believed in Copernicus’ theory that the planets moved around the Sun, but the Catholic Church made him recant his beliefs. For hundreds of years astronomers used telescopes to explore Mars. They made sketches and tried to deduce what Mars was really like. They looked at the white patches and thought there might be ice. They looked at the dark patches and thought there might be vegetation. In 1659, a Dutch astronomer, Christiaan Huygens, drew the first sketch of Mars. Huygens used a telescope of his own design, which had a magnification of 50 times, much stronger that of previous telescopes. He recorded the first feature on Mars, a large dark spot, most likely Syrtis Major, that was named the "Hourglass Sea." Observing the spot over time, he approximated a 24-hour Martian day. The Sytris Major region of Mars is now known to be not one dark feature but a series of dark streaks leading away from a number of small craters. In 1666, Gian Domenico Cassini made sketches of Mars and determined a day length of 24 hours 40 minutes. Cassini also saw the polar caps. In 1813, Honeré Flaugergues, a French amateur astronomer, noticed rapid melting of the ice caps on Mars. He also noted the presence of "yellow clouds" on Mars, later identified as dust clouds.

In the 1800s, observatories with larger and larger telescopes were built around the world. Still, because of the obscuring effects of the Earth's atmosphere, even the best groundbased telescopes could only resolve features no smaller than about 300 kilometers across when Earth and Mars were closest to one another. In 1877, Giovanni Virginio Schiaparelli, director of the Brera Observatory in Milan, began mapping and naming areas on Mars. He named the Martian "seas" and "continents" (dark and light areas) with names from historic and mythological sources. He saw channels on Mars and called them "canali." Canali means channels, but it was mistranslated into "canals" implying intelligent life on Mars. In 1894, Percival Lowell made his first observations of Mars from his private observatory, Lowell Observatory. He decided that the canals were real and ultimately mapped hundreds of them. Lowell believed that the straight lines were artificial canals created by intelligent Martians and were built to carry water from the polar caps to the equatorial regions. In 1895, he published his first book on Mars with many illustrations and, over the next two decades, published two more popular books advancing his ideas. Lowell's theories influenced the young English writer H.G. Wells, who in 1898 published The War of the Worlds. In this novel, Wells created an invasion of Earth by deadly aliens from Mars and launched a whole new genre of alien science fiction. In 1911, "A Princess of Mars", the first of eleven science fiction novels by Edgar Rice Burroughs, was published. Burroughs used Schiaparelli's names for regions on the planet and gave his Martians green skin. On Halloween in 1938, Orson Welles and The Mercury Theater on the Air broadcast a radio version of The War of the Worlds. The story, presented as a series of "live" news bulletins, panicked thousands of listeners who believed that America was being attacked by hostile Martians. Most experienced astronomers never saw the Martian "canals" and for a good reason. We now know that they never existed. The network of crisscrossing lines covering the surface of Mars was only a product of the human tendency to see patterns, even when patterns do not exist. When looking at a faint group of dark smudges, the eye tends to connect them with straight lines. This has been demonstrated by many laboratory and field experiments.

In 1965, America began a series of robotic Mariner missions to Mars. The Mariner 4 spacecraft made the first successful flyby of Mars, transmitting 22 close-up pictures of Mars, showing features as small as 50 kilometers. Mariners 6 and 7 followed in 1969. Images of Mars obtained by the Mariner missions showed a surface containing craters made by meteorite impacts and naturally occurring channels, but no evidence of artificial canals or flowing water. These images led scientists to believe that Mars was like the Moon. In 1971-72, Mariner 9 mapped the surface of the planet in greater detail. Mars was almost totally obscured by dust storms for 1 month when Mariner 9 arrived. But after the dust cleared, Mariner 9 revealed that Mars had huge volcanoes and a grand canyon stretching 4,800 kilometers across its surface. To the surprise of all, ancient riverbeds were discovered on the dry and dusty planet. Mariner 9 mapped 100 percent of the planet's surface and took the first close-up photographs of the tiny Martian moons, Deimos and Phobos.

Many more new discoveries were made about Mars with the two Viking missions of 1976. Vikings 1 and 2 each consisted of an orbiter and a lander. The Viking Orbiters produced detailed images and global maps of Mars. The images from the Viking spacecraft revealed a wide range of geologic features on the planet including massive volcanoes and rift valleys, and evidence of catastrophic flooding in Mars’ past. The Viking landers provided the first images of the surface of Mars. The Viking landers carried out a variety of experiments designed to search for chemical signs of life on the surface of Mars. The three biology experiments aboard the landers discovered unexpected and enigmatic chemical activity in the Martian soil, but provided no clear evidence for the presence of living microorganisms in the soil near the landing sites. These experiments led scientists to believe that Mars was a cold, barren, desert-like world. The weather instruments on the landers determined that the coldest temperature was –85 degrees Celsius and the warmest temperature was –30 degrees Celsius. (We now know that it gets colder and warmer at other spots on the planet.) The wind speeds were about 11 mph with gusts up to 56 mph. Dust storms completely obscured the lander’s view and darkened the sky for several days.

The Mars Pathfinder spacecraft landed on Mars on July 4, 1997, and successfully deployed the first robot vehicle ever placed on Mars, the Sojourner rover. The Pathfinder spacecraft took many photographs of the surface of Mars. Pathfinder made many new discoveries about Mars including evidence that weather processes and flowing water helped create the surface of Mars. That points to a planet that may have been a lot like Earth when it was young. In September 1997, a second spacecraft, the Mars Global Surveyor, was placed in orbit around the planet. It has been mapping the surface of the planet in detail and has taken hundreds of photographs. One of the things that Global Surveyor is looking for is evidence that water may have existed on Mars. The Viking and Surveyor spacecraft have photographed many dry river channels. Some scientists believe that an ocean may have covered the northern plains of Mars 2 to 3 billion years ago and may continue to exist frozen under the surface.

As our exploration continues we move closer towards such exciting ideas as human exploration and even colonization of Mars. Our image of the planet has come a long way, from a god to a possible home, and anything is possible in the future.

Sources:

www.solarviews.com/eng/mars.htm

cass.jsc.nasa.gov/publications/slidesets/msurvey.html

aerospacescholars.org/scholars/earthmars/unit1/Index.htm

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