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Mariner 9

NSSDCA/COSPAR ID: 1971-051A

Description

The Mariner Mars 71 mission was planned to consist of two spacecraft to orbit Mars on complementary missions, but due to the failure of Mariner 8 to launch properly, only one spacecraft was available. Mariner 9 combined mission objectives of both Mariner 8 (mapping 70 % of the Martian surface) and Mariner 9 (a study of temporal changes in the Martian atmosphere and on the Martian surface). For the survey portion of the mission, the planetary surface was to be mapped with the same resolution as planned for the original mission, although the resolution of pictures of the polar regions would be decreased due to the increased slant range. The variable features experiments were changed from studies of six given areas every 5 days to studies of smaller regions every 17 days. Mariner 9 was the first spacecraft to orbit another planet.

Spacecraft and Subsystems

The Mariner 9 spacecraft was built on an octagonal magnesium frame, 45.7 cm deep and 138.4 cm across a diagonal. Four solar panels, each 215 x 90 cm, extended out from the top of the frame. Each set of two solar panels spanned 6.89 meters from tip to tip. Also mounted on the top of the frame were two propulsion tanks, the maneuver engine, a 1.44 m long low gain antenna mast and a parabolic high gain antenna. A scan platform was mounted on the bottom of the frame, on which were attached the mutually bore-sighted science instruments (wide- and narrow-angle TV cameras, infrared radiometer, ultraviolet spectrometer, and infrared interferometer spectrometer). The overall height of the spacecraft was 2.28 m. The launch mass was 997.9 kg, of which 439.1 kg were expendables. The science instrumentation had a total mass of 63.1 kg. The electronics for communications and command and control were housed within the frame.

Spacecraft power was provided by a total of 14,742 solar cells which made up the 4 solar panels with a total area of 7.7 square meters. The solar panels could produce 800 W at Earth and 500 W at Mars. Power was stored in a 20 amp-hr nickel-cadmium battery. Propulsion was provided by a gimbaled engine capable of 1340 N thrust and up to 5 restarts. The propellant was monomethyl hydrazine and nitrogen tetroxide. Two sets of 6 attitude control nitrogen jets were mounted on the ends of the solar panels. Attitude knowledge was provided by a Sun sensor, a Canopus star tracker, gyroscopes, an inertial reference unit, and an accelerometer. Passive thermal control was achieved through the use of louvers on the eight sides of the frame and thermal blankets.

Spacecraft control was through the central computer and sequencer which had an onboard memory of 512 words. The command system was programmed with 86 direct commands, 4 quantitative commands, and 5 control commands. Data was stored on a digital reel-to-reel tape recorder. The 168 meter 8-track tape could store 180 million bits recorded at 132 kbits/s. Playback could be done at 16, 8, 4, 2, and 1 kbit/s using two tracks at a time. Telecommunications were via dual S-band 10 W/20 W transmitters and a single receiver through the high gain parabolic antenna, the medium gain horn antenna, or the low gain omnidirectional antenna.

Mission Profile

Mariner 9 was launched on a 398 million km direct ascent trajectory to Mars by an Atlas-Centaur SLV-3C booster (AC-23). Separation from the booster occurred at 22:36 UT (6:36 p.m. EDT), 13 minutes after launch. The four solar panels were deployed at 22:40 UT. The sensors locked onto the Sun at 23:16, shortly after the spacecraft left the Earth's shadow and Canopus acquisition was achieved at 02:26 UT 31 May. A planned midcourse maneuver was executed on 5 June. Mariner 9 arrived at Mars on 14 November 1971 after a 167 day flight. A 15 minute 23 second rocket burn put the spacecraft into Mars orbit, making Mariner 9 the first spacecraft to orbit another planet. The insertion orbit had a periapsis of 1398 km and a period of 12 hr, 34 min. Two days later a 6 second rocket burn changed the orbital period to just under 12 hours with a periapsis of 1387 km. A correction trim maneuver was made on 30 December on the 94th orbit which raised the periapsis to 1650 km and changed the orbital period to 11:59:28 so that synchronous data transmissions could be made to the Goldstone 64-m DSN antenna.

Imaging of the surface of Mars by Mariner 9 was delayed by a dust storm which started on 22 September 1971 in the Noachis region. The storm quickly grew into one of the largest global storms ever observed on Mars. By the time the spacecraft arrived at Mars no surface details could be seen except the summits of Olympus Mons and the three Tharsis volcanoes. The storm abated through November and December and normal mapping operations began. The spacecraft gathered data on the atmospheric composition, density, pressure, and temperature and also the surface composition, temperature, gravity, and topography of Mars. A total of 54 billion bits of scientific data were returned, including 7329 images covering the entire planet. After depleting its supply of attitude control gas, the spacecraft was turned off on 27 October 1972. Mariner 9 was left in an orbit which should not decay for at least 50 years, after which the spacecraft will enter the martian atmosphere.

The Mariner 9 mission resulted in a global mapping of the surface of Mars, including the first detailed views of the martian volcanoes, Valles Marineris, the polar caps, and the satellites Phobos and Deimos. It also provided information on global dust storms, the triaxial figure of Mars, and the rugged gravity field as well as evidence for surface aeolian activity.

Total research, development, launch, and support costs for the Mariner series of spacecraft (Mariners 1 through 10) was approximately $554 million.

Alternate Names

  • Mariner-I
  • Mariner Mars '71
  • 05261

Facts in Brief

Launch Date: 1971-05-30
Launch Vehicle: Atlas-Centaur
Launch Site: Cape Canaveral, United States
Mass: 558.8 kg
Nominal Power: 500.0 W

Funding Agency

  • NASA-Office of Space Science Applications (United States)

Disciplines

  • Astronomy
  • Planetary Science
  • Space Physics

Additional Information

Questions or comments about this spacecraft can be directed to: Dr. David R. Williams.

 

Personnel

NameRoleOriginal AffiliationE-mail
Mr. Robert H. SteinbacherProject ScientistNASA Jet Propulsion Laboratory 
Mr. Dan SchneidermanProject ManagerNASA Jet Propulsion Laboratory 

Selected References

Steinbacher, R. H., et al., Mariner 9 science experiments - preliminary results, Science, 175, No. 4019, 293, Jan. 1972.

Hartmann, W. K., and O. Raper, The new Mars: The discoveries of Mariner 9, NASA SP-337, Wash., D.C., 1974.

Steinbacher, R. H., and N. R. Haynes, Mariner 9 mission profile and project history, Icarus, 18, No. 1, 64-74, 1973.

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