Mars - Early Telescopic Views Of Mars, Giovanni Schiaparelli, Asaph Hall, Percival Lowell, Inhabited Or Not?
Mars moves through our skies in its stately dance, distant and enigmatic, a world awaiting exploration.
—Astronomer Carl Sagan, 1967
Mars has been a mystery to humans for thousands of years. Although we know much about it now, there is still much more to learn. Mars is the fourth planet from the Sun, and the planet most like Earth in the solar system. It is named after the mythical god of war whom the Romans called Mars and the Greeks called Ares. Mars is also known as the Red Planet, because it looks reddish from Earth. Mars is a dusty, cold world. The average temperature is −64° Fahrenheit. Rays of ultraviolet radiation beat down on the surface continuously. The atmosphere is nearly all carbon dioxide.
People on Earth have always been fascinated with the idea of life on Mars. Ancient people could see Mars as a pale reddish light in the nighttime sky. They believed that it was stained with the blood of fallen warriors. Once telescopes were invented people had a better view of the planet, but many still thought it was inhabited. Patterns of straight lines could be seen on the surface. To some these were evidence of water canals dug into the ground by hard-working Martians. The notion lingered for decades in the public imagination.
At the dawn of the Space Age, humans sent robotic probes to Mars to settle the question once and for all. These probes found a frozen wasteland of fine powdery dust. Neither canals nor Martians could be located. There was some water vapor in the atmosphere and some frozen water at the planet's poles. Where there is water, there is potential for life similar to that found on Earth. Scientists continue to send probes to search for water and life.
In January 2004 President George W. Bush proposed that astronauts travel to Mars and explore the planet. It will be expensive and difficult. It takes six months to fly to Mars. The United States will need new rockets and spacecraft and some clever ways to keep astronauts healthy and happy on such a long journey. These are great challenges, but the idea is tantalizing—humans standing on another planet. Finally, there would be some life on Mars.
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The Italian astronomer Galileo Galilei (1564–1642) was probably the first to see Mars through a telescope. He noticed that sometimes it appeared larger than at other times. He believed that its distance from Earth was changing over time. During the seventeenth century Johannes Kepler (1571–1630) studied Mars's movement for years. His observations helped him to develop the laws…
During the late 1800s Mars became the topic of a debate that would go on for decades. The controversy was sparked by the observations of an Italian astronomer named Giovanni Schiaparelli (1835–1910). He created some of the first maps of the planet and assigned names to prominent features. Schiaparelli's naming system relied on place names taken from the Bible and ancient mythology. S…
In August 1877 the American astronomer Asaph Hall (1829–1907) discovered that Mars has two moons. Centuries before him, Johannes Kepler guessed that Mars had two moons, but this had never been verified. Hall reported that the moons were very small and orbited close to the planet's surface. This had made them impossible to see before. Hall made the discovery using a powerful new teles…
Percival Lowell (1855–1916) was a mathematician and amateur astronomer who greatly popularized the idea that Mars was inhabited by intelligent beings. In 1894 he founded the Lowell Observatory in Flagstaff, Arizona. Perched at an altitude of 7,000 feet, the observatory provided one of the best views yet of the cosmos, including Mars. For fifteen years Lowell studied the Red Planet and wrote…
Lowell's ideas were not shared by most astronomers of the time. In 1908 the distinguished journal Scientific American noted that "Lowell is practically alone in the astronomical world in believing that he has proven that Mars is inhabited." Scientists pointed out that artificial canals would have to be hundreds of miles wide to be visible from Earth. Furthermore, Mars was beli…
Around the turn of the nineteenth century Mars became a popular topic of science fiction. Before that time there is little mention of the Red Planet. One notable exception is a fanciful story published in 1726 by the Irish writer Jonathan Swift (1667–1745). Gulliver's Travels mentions the discovery of two Martian moons by astronomers living on the fictional island of Laputa. Oddly en…
Mars is a small planet. Its diameter is about half that of Earth. Mars is twice as large as Earth's moon. A Martian day lasts twenty-four hours and thirty-nine minutes and is called a sol. It takes Mars 687 days to travel around the Sun. The planet has different seasons throughout its orbit, because it is tilted, just like Earth. During a Martian winter, at the poles the temperature can dro…
After the Moon the planet Mars was the destination of choice during the early days of space travel. The Soviet Union was particularly eager to reach the Red Planet before the United States. A historical log of all Mars missions is presented in Table 7.1. Historically, spacecraft have had a difficult time making it to Mars in working order and staying that way. As shown in Table 7.1, more than half…
The Mariner program included a series of spacecraft launched by NASA between 1962 and 1973 to explore the inner solar system (Mercury, Venus, and Mars). These were relatively low-cost missions conducted with small spacecraft launched atop Atlas-type rockets. Each spacecraft weighed between 400 and 2,200 pounds. They were designed to operate for several years and collect specific scientific data ab…
Within only four years NASA went from orbiting Mars to a landing on the planet. In 1976 the Viking mission was the first American spacecraft to land safely on Mars. For the mission NASA built two identical spacecraft, each containing an orbiter and lander. The two spacecraft entered orbit around Mars and released their landers to descend to the planet's surface. The spacecraft launched only…
During the 1980s NASA was busy running the space shuttle program. There was no money to send spacecraft
to Mars. Luckily, a piece of Mars turned up on Earth. On December 27, 1984, a meteorite hunter found a four-pound rock on the Allan Hills ice field in Antarctica (the South Pole). The rock was grayish-green and covered with pits and gouges. It was given the designation ALH84001. The National Sc…
More than twenty years passed between the launch of the highly productive Viking missions and another successful mission to Mars. In November 1996 the Mars Global Surveyor took off from Cape Canaveral, Florida, atop a Delta II rocket. The spacecraft arrived near the planet ten months later. To save on fuel the Global Surveyor was put into its final Martian orbit very slowly through a process calle…
Mars Pathfinder was a mission conducted as part of NASA's Discovery program. This was the agency's "faster, better, cheaper" approach to space science. The mission was developed in only three years and cost $265 million. On December 4, 1996, the spacecraft launched atop a Delta II rocket from the Cape Canaveral Air Station in Florida. Pathfinder traveled for seven month…
In 1895 Percival Lowell said "If Mars be capable of supporting life, there must be water upon his surface; for to all forms of life water is as vital a matter as air. To all organisms water is absolutely essential. On the question
FIGURE 7.2 The Sojourner rover "Sojourner Rover," in NASA Facts: Mars Pathfinder, National Aeronautics and Space Administration, Jet Propulsion La…
Scientists all over the world knew that 2003 was going to be a good year to go to Mars, because Mars would be in opposition to Earth. On August 28, 2003, the Sun, Earth, and Mars were going to line up in a row. This happens every twenty-six months. The opposition of 2003 was special, because it was going to occur while Mars was at its closest point to the Sun. This configuration is known as a peri…
The Mars Express mission is the first mission to Mars by the European Space Agency (ESA). It was timed to put the spacecraft in flight near the time of Mars's perihelic opposition. In June 2003 the spacecraft was launched toward Mars from the Baikonur launch pad in Kazakhstan. A Russian Soyuz-Fregat rocket was used as the launch vehicle. The spacecraft included two parts—an orbiter a…
Another Mars mission began in 2003 with the launch of NASA's twin Mars Exploration Rovers (MERs). Each spacecraft carried a lander to Mars. Inside each lander was a rover about the size of a golf cart, designed to explore the Martian surface. The rovers were named Spirit and Opportunity. The names were the winning entries in a naming contest NASA held in 2002. The winning entry came from a …
On August 12, 2005, NASA launched the Mars Reconnaissance Orbiter (MRO) toward the Red Planet. The spacecraft was approximately twenty-one by forty-five feet in size and weighed more than two tons. A powerful Atlas V two-stage rocket was used to hoist the heavy MRO into space. Figure 7.10 shows some of the main features of the orbiter. The MRO includes sophisticated radar, mineralogy, and atmosphe…
NASA plans to launch robotic spacecraft to Mars during the oppositions of 2007 and 2009. In 2008 a spacecraft named Phoenix Mars Scout is scheduled to land on the Martian surface to investigate the water ice near the north polar region. It will also search for organic molecules in the soil. In 2009 a rover named the Mars Science Laboratory will be sent to conduct detailed chemical analysis of the …
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