NASA's Mariner 9 mission rewrote the book on Mars by discovering channels, polar layered materials, shield volcanoes, sand dunes, and an enormous canyon system. In this Mariner 9 image, a series of massive landslides are visible on the canyon floor. The older (bottom-most) landslide has longitudinal ridges which formed parallel to flow direction, while the younger slides have concentric ridges. Dunes are also visible near the bottom of the image.

Image by NASA/JPL/Arizona State University
  • On May 30, 1971, the National Aeronautics and Space Administration (NASA) launched an unmanned space probe called Mariner 9 from Cape Canaveral, Florida. Mariner 9 carried equipment that would send images and other data back to Earth after the spacecraft reached its target—orbit around Mars. Mariner 9 reached the Red Planet more than five months later.
    Mariner 9, Mars' first artificial satellite, spent nearly one year in orbit. It sent back thousands of images: enormous volcanoes, huge canyons, and even evidence of very old riverbeds. Mariner 9 also sent the first close-up images of the two Martian moons, Phobos and Deimos.
    The Mariner 9 mission was a new way to explore the solar system. Instead of flying by a planet, the space probe orbited around it to get more detailed information. Mariner 9 was a very successful mission, and it prompted many later missions to Mars.
  • Term Part of Speech Definition Encyclopedic Entry
    artificial satellite Noun

    object launched into orbit.

    canyon Noun

    deep, narrow valley with steep sides.

    Encyclopedic Entry: canyon
    data Plural Noun

    (singular: datum) information collected during a scientific study.

    equipment Noun

    tools and materials to perform a task or function.

    moon Noun

    natural satellite of a planet.

    Encyclopedic Entry: moon
    NASA Noun

    (National Aeronautics and Space Administration) the U.S. space agency, whose mission statement is "To reach for new heights and reveal the unknown so that what we do and learn will benefit all humankind."

    orbit Noun

    path of one object around a more massive object.

    planet Noun

    large, spherical celestial body that regularly rotates around a star.

    Encyclopedic Entry: planet
    solar system Noun

    the sun and the planets, asteroids, comets, and other bodies that orbit around it.

    spacecraft Noun

    vehicle designed for travel outside Earth's atmosphere.

    space probe Noun

    set of scientific instruments and tools launched from Earth to study the atmosphere and composition of space and other planets, moons, or celestial bodies.

    unmanned Adjective

    lacking the physical presence of a person.

    volcano Noun

    an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.

    Encyclopedic Entry: Plate Tectonics and Volcanic Activity