[7] The mission was considered successful and is credited with helping to form most of the body of knowledge about Mars through the late 1990s and early 2000s.

Propulsion was furnished by a bipropellant (monomethylhydrazine and nitrogen tetroxide) liquid-fueled rocket engine which could be gimballed up to 9 degrees.

Two 30-amp·hour, nickel-cadmium, rechargeable batteries provided power when the spacecraft was not facing the Sun, during launch, while performing correction maneuvers and also during Mars occultation.

They showed that floods of water broke through dams, carved deep valleys, eroded grooves into bedrock, and travelled thousands of kilometers.

Large areas in the southern hemisphere contained branched stream networks, suggesting that rain once fell.

[11][12][13] Regions, called "Chaotic Terrain," seemed to have quickly lost great volumes of water, causing large channels to be formed.

[14] Underground volcanism may have melted frozen ice; the water then flowed away and the ground collapsed to leave chaotic terrain.

To prevent contamination of Mars by Earth organisms, each lander, upon assembly and enclosure within the aeroshell, was enclosed in a pressurized "bioshield" and then sterilized at a temperature of 111 °C (232 °F) for 40 hours.

For thermal reasons, the cap of the bioshield was jettisoned after the Centaur upper stage powered the Viking orbiter/lander combination out of Earth orbit.

Terminal descent (after use of a parachute) and landing used three (one affixed on each long side of the base, separated by 120 degrees) monopropellant hydrazine engines.

Power was provided by two radioisotope thermoelectric generator (RTG) units containing plutonium-238 affixed to opposite sides of the lander base and covered by wind screens.

Four wet cell sealed nickel-cadmium 8 Ah (28,800 coulombs), 28 volt rechargeable batteries were also on board to handle peak power loads.

Both these antennae allowed for communication directly with the Earth, permitting Viking 1 to continue to work long after both orbiters had failed.

From the center of this side extended the sampler arm, with a collector head, temperature sensor, and magnet on the end.

An interior environmentally controlled compartment held the biology experiment and the gas chromatograph mass spectrometer.

One experiment turned positive for the detection of metabolism (current life), but based on the results of the other two experiments that failed to reveal any organic molecules in the soil, most scientists became convinced that the positive results were likely caused by non-biological chemical reactions from highly oxidizing soil conditions.

The validity of the positive 'Labeled Release' (LR) results hinged entirely on the absence of an oxidative agent in the Martian soil, but one was later discovered by the Phoenix lander in the form of perchlorate salts.

[23] Researchers found that perchlorate will destroy organics when heated and will produce chloromethane and dichloromethane, the identical chlorine compounds discovered by both Viking landers when they performed the same tests on Mars.

Nonetheless, on April 12, 2012, an international team of scientists reported studies, based on mathematical speculation through complexity analysis of the Labeled Release experiments of the 1976 Viking Mission, that may suggest the detection of "extant microbial life on Mars.

[27] The leader of the imaging team was Thomas A. Mutch, a geologist at Brown University in Providence, Rhode Island.

[28]  There are also three narrow band low resolution diodes (named BLUE, GREEN and RED) for obtaining color images, and another three (IR1, IR2, and IR3) for infrared imagery.

[35] This was decades before NASA's "faster, better, cheaper" approach, and Viking needed to pioneer unprecedented technologies under national pressure brought on by the Cold War and the aftermath of the Space Race, all under the prospect of possibly discovering extraterrestrial life for the first time.

[35] The experiments had to adhere to a special 1971 directive that mandated that no single failure shall stop the return of more than one experiment—a difficult and expensive task for a device with over 40,000 parts.

[5] The Viking 1 lander was found to be about 6 kilometers from its planned landing site by the Mars Reconnaissance Orbiter in December 2006.

[37] Each Viking lander carried a tiny dot of microfilm containing the names of several thousand people who had worked on the mission.