The Case for Mars by Robert Zubrin Read Free Book Online Page B

industrial revolutions began—humanity’s first encounter with Mars had paid off handsomely.
    VOYAGES BY TELESCOPE
     
    Kepler had used Mars to prove that the Earth was a planet. By implication, therefore, the planets, those little moving lights in the sky, were really vast worlds like the Earth. But how to explore these incredible new bodies? A tool was soon at hand. Barely a year after Kepler published his New Astronomy , Galileo turned a new instrument toward the heavens—a telescope. His discovery of mountains on the Moon and “three little stars” dancing about Jupiter over the course of several weeks of observing gave additional credence to the Keplerian view of the universe. Soon enough, other telescopes were trained on Mars.
    The Italian astronomer Francisco Fontana produced in 1636 the first drawing of Mars through the telescope, though viewed today it reveals no recognizable features. In 1659 the Dutch astronomer Christiaan Huygens produced the first drawing that shows a known Martian feature, a roughly triangular dark blotch that appears on the planet’s face, today known as Syrtis Major. By carefully observing Syrtis and similar features, early astronomers determined that the Martian day, or sol, was close to Earth’s. In 1666, the Italian Giovanni Cassini measured the Martian day at 24 hours, 40 minutes, about two and one-half minutes longer than today’s accepted measure of 24 hours, 37 minutes, 22 seconds. Although Cassini was also apparently the first to note one of Mars’ polar caps, Huygens in 1672 produced the first sketch of one of the caps. Utilizing observations made between 1777 and 1783, William Herschel, discoverer of Uranus, noted that Mars should have seasons, as its polar axis was tilted about 30° (24° is the modern value) to its orbital plane.
    Observations of Mars continued through the decades, especially around “oppositions,” those times when Mars (technically, any planet outside Earth’s orbit) lies on the opposite side of the Earth from the Sun. At these times, Mars is at its closest to Earth and thus shines most brightly in the sky. By the early nineteenth century, astronomers had collected a basketful of basic Mars statistics: its orbital period; the length of its day; the planet’s mass and density; distance from the Sun, and surface gravity. But what truly intrigued observers was the changing face of Mars. Through the years the telescope’s eyepiece revealed that Mars’ face was mottled with ar darkpatches that came and went with time. Likewise, the bright white spots observers noted at the poles appeared to vary with the Martian seasons, expanding and contracting over the course of a Martian year. And Mars apparently hosted an atmosphere, as some observers spied vague indications of clouds above the Martian surface.
    The opposition of 1877 proved especially fruitful for observers and for Martian studies. Asaph Hall of the U.S. Naval Observatory discovered two small moons of Mars and promptly named them Phobos and Deimos—fear and terror, an appropriate entourage for the planet of war. But in hindsight, 1877 is perhaps best remembered for a series of observations that launched a turbulent episode in the history of Mars observations and one of the strangest chapters in the history of astronomy.
    Among those who turned a telescopic eye toward Mars in 1877 was the Italian astronomer Giovanni Schiaparelli, director of the Brera Observatory in Milan. Schiaparelli’s reports of his observations noted the location of more than sixty features on the Martian surface. But, along with many standard features, he reported sighting linear markings crisscrossing the face of Mars. He named these features after terrestrial rivers—Indus, Ganges—but referred to them in his writings as “canali,” the Italian plural for channels or grooves. While not the first to note these strange markings, he was the first to identify an extensive system of “canali.” More than a decade later,