Mission Information
MISSION_START_DATE 1968-06-01T12:00:00.000Z
MISSION_STOP_DATE 1973-06-01T12:00:00.000Z
Mission Overview
      On November 14, 1971, Mariner 9 became the first spacecraft to
      orbit another planet.  Six experiments were carried as part of
      the science payload: television, ultraviolet spectrometer,
      infrared spectroscopy, infrared radiometry, S-band occultation
      and celestial mechanics.  Two experiments (S-band occultation
      and celestial mechanics) utilized the radio telemetry subsystem
      to derive data; the other required specially developed
      instruments, mounted, and boresighted to each other, on the
      spacecraft's scan platform.   Pre-launch mission planning
      encompassed two separate, but complementary, missions.  The
      orbit of each spacecraft was optimized to match the
      corresponding objective.  The mapping mission was designed with
      an Earth-synchronous orbit (about a 12-hr periods) to maximize
      antenna utilization, or communications efficiency.  For maximum
      surveillance of an area, it was designed with a steep
      inclination (80 degrees) to the equatorial plane of Mars.  The
      dynamic objective dictated a Mars-synchronous (or
      sub-synchronous) orbit and a lower (50 degree) inclination for
      closer observations of specific areas.  The plans for the two
      missions were in detailed stages of development on May 9, 1971
      when Mariner 8 was lost because of guidance difficulties in the
      second stage of the launch vehicle.   It was determined that an
      orbit for a single-spacecraft mission could be developed to meet
      all basic mission and specific science objectives.  A
      single-spacecraft plan, involving an inclination of 65 degrees,
      a period of about 12 hours, a periapsis altitude of 1350 Km, and
      an arrival date of November 14, 1971, was evaluated and
      formalized in 2 weeks.
      Mariner 9 Statistics
        Total mission 516 days
        Required minimum useful orbital lifetime - 90 days
        Actual useful orbital lifetime - 349 days
        Distance from Earth to Mars on 10/27/72 - 383,675,000Km
        Commands received by Mariner 9 - 45,960
        TV pictures received of Mars and its satellites - 7329
        TV shutter actuations - 14,004
        Required minimum mapping coverage - 70% of planet
        Actual mapping coverage obtained - 100% of planet
        Science data received from Mariner 9 - 54 billion bits
      Mariner 9 'firsts'
        1.  Orbit another planet,
        2.  Detail observation of Martian Atmospheric Changes,
        3.  Complete mapping of another planet,
        4.  Detail observations of satellites of another planet,
        5.  Observation by spacecraft of receding polar cap.
      Mariner 9 'Discoveries'
        1.  Tectonic action on Mars (Crust movement),
        2.  Existence of volcanoes and lava flows,
        3.  Evidence of past fluid flow,
        4.  Eolian activity (wind erosion and deposition),
        5.  Rough gravity field,
        6.  Triaxiality of Mars,
        7.  Evidence of process of differentiation of Mars similar to
            that of Earth,
        8.  Permanent residual polar cap.
        On October 28, 1972, Mariner 9 ran out of attitude control gas
        and was commanded to be silent for the final time.  It is
        estimated that Mariner 9 will remain in Mars orbit for more
        than 50 years.
    Mission Phases
        On June 5th, a planned trajectory correction was made.
        Martian ephemeris data and spacecraft tracking calculations
        were determined with such accuracy that no other midcourse
        corrections were necessary during the 167 day flight to Mars.
        Other events during cruise were scan calibration no.  1 on
        October 1, scan calibration no.  2 on October 8, Mars TV
        calibration on November 8 and November 9.
        Spacecraft Id                  : MR9
        Target Name                    : MARS
        Mission Phase Start Time       : 1971-05-30
        Mission Phase Stop Time        : 1971-11-14
        Spacecraft Operations Type     : ORBITER
        Mariner 9 was successfully launched from Cape Kennedy, Florida
        at 6:23 PM EDT.  The Centaur-Mariner 9 separation occurred at
        6:36 PM EDT.
        Spacecraft Id                  : MR9
        Target Name                    : MARS
        Mission Phase Start Time       : 1971-05-30
        Mission Phase Stop Time        : 1971-05-30
        Spacecraft Operations Type     : ORBITER
        The 1398 Km periapsis altitude of the insertion orbit was
        accurate to with 50 Km from the aiming point, and the initial
        period of 12 hr and 34 min was within seconds of the time
        desired for the insertion orbit.  The non-synchronization with
        Earth provided the timing slip until coincidence of the
        Goldstone 64-m antenna zenith position and orbit periapsis was
        obtained and a trim maneuver 'locked' the two into
        synchronization.   On November 16, the spacecrafts' orbital
        period was changed by more than 30 min by a 6-sec firing of
        the rocket engines.  However, because of the previously
        unknown gravity-field variation of the planet the average
        orbital period was found to be slightly shorter that the
        11:58:52 planned, gradually changing the time relationship of
        periapsis to the view period of the 64-m antenna at Goldstone,
        California, which would eventually affect data playbacks.   On
        December 30 (revolution 94), a second trim maneuver adjusted
        the orbital period, correcting periapsis-passage timing with
        the view period of the 64-m antenna.  This new orbit
        established a higher periapsis altitude, which provided a
        broader area coverage for each television picture, thus
        requiring fewer picture to complete the desired mapping of 70%
        of the surface during the standard 90 day mission.  The
        broader area coverage for each pictured resulted in a
        corresponding loss of surface resolution.   About 122 days
        after orbit insertion, the pointing direction of the
        spacecraft's high-gain antenna drifted off of Earth, and
        communications became more difficult.  A high-gain antenna
        maneuver (HGAM) of the spacecraft became necessary to point
        the antenna to Earth.   On October 27, 1972, telemetry data
        indicated that the spacecraft was no longer capable of holding
        the fixed attitude and, as the last battery power was being
        used, a final command was sent to stop transmitting.  The
        slowly tumbling Mariner 9 will remain in orbit for a minimum
        of 50 years before it enters the atmosphere of Mars,
        disintegrates, and falls to the surface.
        Spacecraft Id                  : MR9
        Target Name                    : MARS
        Mission Phase Start Time       : 1971-11-14
        Mission Phase Stop Time        : 1979-10-27
        Spacecraft Operations Type     : ORBITER
To map the surface of the planet and to observe the dynamic
        characteristics of its surface and atmosphere from orbit for a
        period of 90 days.
REFERENCE_DESCRIPTION Mariner Mars 1971 Project Final Report, Science Experiment Reports, JPL Technical Report 32-1550, Vol. V, Aug. 20, 1973.