Editing Viking program (section)

==Mission end==
{| class="wikitable"
|+The craft all eventually failed, one by one, as follows:<ref name="NASA-20061218" />
! Craft || Arrival date || Shut-off date || Operational lifetime || Cause of failure
|-
| ''Viking 2'' orbiter || August 7, 1976 || July 25, 1978 || 1 year, 11 months, 18 days || Shut down after fuel leak in propulsion system.
|-
| ''Viking 2'' lander || September 3, 1976 || April 11, 1980 || 3 years, 7 months, 8 days || Shut down after battery failure.
|-
| ''Viking 1'' orbiter || June 19, 1976 || August 17, 1980 || 4 years, 1-month, 19 days || Shut down after depletion of [[Spacecraft attitude control|attitude control]] fuel.
|-
| ''Viking 1'' lander || July 20, 1976 || November 13, 1982 || 6 years, 3 months, 22 days || Shut down after human error during software update caused the lander's antenna to go down, terminating power and communication.
|}
The Viking program ended on May 21, 1983. To prevent an imminent impact with Mars the orbit of ''Viking 1'' orbiter was raised on August 7, 1980, before it was shut down 10 days later. Impact and potential contamination on the planet's surface is possible from 2019 onwards.<ref name="nssdc-viking1orbiter">{{Cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075A |title=Viking 1 Orbiter spacecraft details |access-date=July 10, 2019 |date=March 20, 2019 |work=[[NASA Space Science Data Coordinated Archive]] |publisher=NASA }}</ref>

The ''Viking 1'' lander was found to be about 6 kilometers from its planned landing site by the [[Mars Reconnaissance Orbiter]] in December 2006.<ref>{{cite magazine| url=https://www.newscientist.com/article/dn10727-probes-powerful-camera-spots-vikings-on-mars.html#.UlIB7FDrwbN| title=Probe's powerful camera spots Vikings on Mars| last=Chandler| first=David| magazine=New Scientist| date=December 5, 2006| access-date=October 8, 2013}}</ref>