Mission Type: Flyby
Launch Vehicle: Atlas-Centaur (AC-20 / Atlas 3C no. 5403C / Centaur D-1A)
Launch Site: Eastern Test Range / launch complex 36B, Cape Canaveral, U.S.A.
NASA Center: Jet Propulsion Laboratory
Spacecraft Instruments: 1) imaging system (two TV cameras); 2) infrared spectrometer; 3) ultraviolet spectrometer; 4) infrared radiometer; 5) celestial mechanics experiment; and 6) S-band occultation experiment
Spacecraft Dimensions: octagonal frame: 138.4 cm diagonally, 45.7 cm deep; deployed solar panels (tip to tip): 5.7 m; height: 3.35 m
Spacecraft Power: 4 solar panels and a 1200 W-hr rechargeable silver-zinc battery for backup power
Maximum Power: 800 W near Earth, 449 W at Mars
Antenna Diameter: 1 m diameter (high-gain parabolic antenna)
S-Band Data Rate: Channel A (engineering data): 8 1/3 or 33 1/3 bps; Channel B (scientific data): 66 2/3 or 270 bps; Channel C (science data): 16,200 bps
Maximum Data Rate: 16,200 bps (channel C, science data)
Project Manager: Harris M. Schurmeier
Principal Scientists: Dr. John A. Stallkamp (Project Scientist)
Total Cost: total research, development, launch, and support costs for the Mariner series (Mariners 1 through 10): $554 million
References:
Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, Monographs in Aerospace History No. 24, by Asif A. Siddiqi

National Space Science Data Center, http://nssdc.gsfc.nasa.gov/

Solar System Log by Andrew Wilson, published 1987 by Jane's Publishing Co. Ltd.

Mariners 6 and 7, identical spacecraft intended to fly by Mars, were the first Mariner spacecraft launched by the Atlas-Centaur, permitting a heavier instrument suite. Both spacecraft were intended to study the surface and atmosphere of Mars during close flybys. All onboard instrumentation was designed to collect data on Mars; there were no experiments for study of interplanetary space.

The 3.35-meter-tall spacecraft was constructed around an eight-sided magnesium framework with four rectangular solar panels for 449 watts of power at the distance of Mars. The heart of the spacecraft was the 11.8-kilogram Control Computer and Sequencer (CC&S), which was designed to operate Mariner independently without intervention from ground control.

After a midcourse correction on 1 March 1969 and preliminary imaging sessions (50 photos) on 28 July 1969, Mariner 6 flew by Mars at 05:19:07 UT on 31 July 1969 at a distance of 3,429 kilometers. Just 15 minutes prior to closest approach (just south of the Martian equator), the two TV cameras on a scan platform began taking photos of the planet automatically every 42 seconds. During a period of 17 minutes, Mariner 6 took 24 near-encounter photos that were stored and later transmitted to Earth.

The photos showed heavily cratered and chaotic areas not unlike parts of the Moon. Images of the south polar region showed intriguing detail of an irregular border. The scientific instruments indicated that the polar cap gave off infrared radiation consistent with solid carbon dioxide. Mariner 6 found surface pressure to be equal to about 30.5 kilometers above Earth's surface. Atmospheric composition was about 98 percent carbon dioxide. A surface temperature of -73°C was recorded at the equator at night; -125°C was recorded at the south polar cap.