Mars is the fourth planet from the Sun and sometimes is called the Red Planet. The rocks, soil and sky of Mars have a distinct red color, which has been observed by stargazers for thousands of years. The ancient Romans named Mars in honor of their god of war. Other cultures have had similar names for this planet. The ancient Egyptians, for example, named the planet Her Descher, which means "the red one".
The atmosphere of Mars is very different from Earth's atmosphere. It contains mostly carbon dioxide (C02) gas, with small amounts of other gases. Martian air contains only 1/1000 as much water as our air, but even this small amount can form clouds that ride high in the atmosphere or swirl around the tops of giant volcanoes. There is evidence that in the past Mars had a much denser atmosphere that allowed water to flow on the planet. Mars has features which resemble shorelines, gorges, riverbeds and islands. These features suggest that there were great rivers on Mars millions of years ago.
Before space exploration, Mars was considered the best candidate for having extraterrestrial life. When astronomers looked at Mars through a telescope, they could see changes in the color of the planet, which they thought were caused by changes in the seasons. Astronomers thought that there was a bloom of green plants during the warmer months and that the Martian vegetation became dormant in winter months. Scientists thought they saw straight lines crossing its surface. This led to the belief that canals for irrigation had been constructed on Mars by intelligent creatures.
In 1938, the American film director Orson Welles made a radio drama in New York city. The drama was based on a book called The War of the Worlds by H.G. Wells. When people listened to the radio story, many people belived that Martians were attacking Earth, and enough people believed in the story of invading Martians to cause a panic. The recent American movie Independence Day, where aliens attempt to conquer the Earth and are defeated by a computer virus, also appears to be based on this famous story.
In 1975, the American space probe Mariner 4 visited Mars and sent back 22 close-up pictures to Earth. The photographs showed a surface with many craters and naturally occurring channels but no sign of artificial canals or flowing water. In July and September 1976, Viking 1 and 2 landed on the surface of Mars. The three biology experiments aboard each space probe discovered unexpected and puzzling chemical activity in the Martian soil, but showed no clear signs of life. Many biologists believe the combination of solar radiation that saturates the surface, the extreme dryness of the soil and the soil chemistry make it impossible for living organisms to survive in the Martian soil. It is possible, however, that there was life on Mars at some time in the distant past.
The exploration of Mars by scientists from Russia and the United States continues. The Mars Pathfinder was launched by the USA in December, 1996, and will arrive at Mars on July 4, 1887. When the Pathfinder lands on Mars, it will release a small mobile car which will travel around Mars, taking pictures and gathering data and sending it back to Earth.
In the United States and other countries, however, there is a growing debate about whether or not a manned mission to Mars should take place in the near future. In the US and in other countries, organizations such as the Students for the Exploration and Development of Space (SEDS), Space Frontier Foundation, the Deep Space Exploration Society and the First Millennial Foundation are lobbying governments everywhere to attempt a manned mission to Mars within the next few years. Such a mission would be very costly, much more so than the Apollo lunar landing program. By some estimates, it would cost as much as 7 trillion Won ($100 billion US) to conduct a manned mission to Mars. Some scientists and entrepreneurs, however, believe it could be undertaken for much less cost. They believe that humankind should undertake a large-scale, long-term committment to explore, colonize and terraform the Red Planet.
According to NASA Administrator Daniel Goldin, "we must accomplish at
least four objectives before we are prepared for a Mars mission. We must
successfully build and operate the planned international
Space Station, gain working-level experience with other nations in space
cooperation, develop an affordable mission scenario that can be accomplished
in about one decade, and allow time for the world economy to improve substantially". With these goals in mind, NASA currently plans to operate the Space Station for at least the first decade of the next century, sending astronauts back to the Moon or on to Mars during the second decade of the new century. This time frame could change with technological breakthroughs.
"The dream of human exploration of Mars is intimately tied to
the belief that new lands create new opportunities", says Dr. Michael Duke of the
NASA Johnson Space Flight Center. "In human history,
migrations of people have been stimulated by overcrowding, exhaustion of
resources, the search for religious or economic freedom, competitive
advantage, and other human concerns. Rarely have humans entered new
territory, then completely abandoned it. In the past, there have always
been a few people who were adventurous enough to adopt a newly-found
territory as their home. Most of these settlements have eventually
become economically self-sufficient, and have enlarged the genetic and
economic diversity of humanity. The technological revolution of the 20th
Century, with high speed communication and transportation and integrated
economic activity, has reversed the trend toward human diversity; however,
settlement of the planets can once again enlarge the sphere of human action
"The settlement of Mars presents new problems and challenges.
Principal among these is the absence of a livable natural environment.
That, and the current high cost of transportation are the main barriers
to human expansion there. The fact that humans, once on Mars, can not
easily return to the Earth, and then only at specified times
approximately 26 months apart, makes it necessary to develop systems with
high reliability and robustness. The creation of a livable, artificial
environment, is technically feasible. The high cost of transportation
will ultimately be reduced.
"The human exploration of Mars will be an enterprise that confirms
the potential for humans to leave their home planet and make their way
outward into the cosmos", says Duke.