Viking 1 was the first spacecraft sent to Mars as part of NASA's Viking program. NASA's Viking program to Mars was composed of two spacecraft which were Viking 1 and Viking 2. Viking 1 successfully landed on Mars on July 20, 1976. It was launched on August 20, 1975 using a Titan/Centaur launch vehicle and arrived at Mars on June 19, 1976. Until broken by Opportunity on May 19, 2010, Viking 1 held the record for the longest Mars surface mission of 2307 days.

In its instruments of the orbiter, the two vidicon cameras were there for imaging, an infrared spectrometer for water vapor mapping (MAWD) and infrared radiometers for thermal mapping (IRTM). The beginning of solar conjunction on November 5, 1976 ended the orbiter primary mission. After 1485 orbit on August 17, 1980, Operations were terminated. At the time of separation, from the orbiter on July 20 at 08:51 UTC, the lander was orbiting at about 5 kilometres per second (3.1 miles per second). The lander was reoriented for atmospheric entry after a few hours at about 300 kilometres altitude. The lander arrived on Mars with a relatively light jolt because the legs of lander had honeycomb aluminum shock absorbers to soften the landing. NASA calculated that the surface would not be heated by more than one 1°C therefore the landing rockets used an 18-nozzle design to spread the hydrogen and nitrogen exhaust over a large area. A more straightforward design would not have served since most of Viking's experiments focused on the surface material.



Transmission of the first surface image began 25 seconds after landing and took about 4 minutes and during these minutes the lander activated itself. On the day after the landing the first color picture of the surface of Mars was taken. The Viking Landers transmitted images of the surface, took surface samples and analyzed them for composition and signs of life, studied atmospheric composition and meteorology, and deployed seismometers. Viking-1 transmitted over 1400 images.

Viking purpose was to look for evidence of life and it carried a biology experiment for that. The Viking 1 Lander was named the Thomas Mutch Memorial Station in January 1982 in honor of the leader of the Viking imaging team.

The Viking 2 lander operated on the surface for 1316 days. It was turned off on April 11, 1980 after battery failure. The orbiter returned almost 16,000 images in 706 orbits around Mars and worked until July 25, 1978.