Target Mars: The Mars Observer mission, which will cost from $900 million to $1 billion, is the first U.S. exploration of Mars since the Viking missions were launched in 1975. Vikings 1 and 2 landed on the surface in 1976 after a series of Mariner space probes. The former Soviet Union sent several probes. The latest, Phobos 2, reached Mars orbit in 1989.
The mission: Mars Observer's goal is to examine the planet's geology and climate. It will produce detailed global photographic and topographic maps of Mars.
The route: The spacecraft will take a curving, 450-million-mile path to reach Mars on Aug. 24, 1993. Scientists hope to begin research in December, 1993. The craft is to relay information at least until 1995.
The Planet Mars
Name: Named for the Roman god of war and called the Red Planet for the reddish hue of its dust and soil. It is the fourth planet, 141 million miles from the sun between Earth and Jupiter.
Moons: It has two small, irregularly shaped moons--Phobos and Deimos.
Characteristics: Landscape is barren, rocky, cratered desert with extinct volcanoes, including 88,000-foot Olympus Mons. Polar icecaps advance and retreat with the seasons. Extensive dry river channels were cut long ago by running water that once gushed from underground. It has a thin atmosphere, largely carbon dioxide. Temperatures vary from about 225 degrees below zero to 70 degrees Fahrenheit. Cyclones can sweep the planet. Winds reach hundreds of miles per hour, whipping up global dust storms.
Myths: When 19th-Century astronomers saw what looked like canals on Mars, a legend grew that they were built by intelligent beings. Mariner spacecraft in the 1960s and early '70s found only dry river channels. The twin Viking landers in 1976 found no sign of life.