Viking 1
- id: PRB-006
- launch_year: 1975
- launch_date: 1975-08-20
- operated_by: NASA
- visited: Mars
- status: completed
- confidence: believed-correct
- sources: NASA NSSDCA Master Catalog, JPL missions, NASA History Division
Viking 1 launched on 20 August 1975, an orbiter–lander pair run by NASA. On 20 July 1976 its lander set down on the Chryse Planitia plain of Mars — the first spacecraft to land on Mars and carry out its full mission from the surface.
The lander returned the first photographs from the Martian surface and ran a suite of biology experiments whose results — chemically active soil, but no unambiguous sign of life — are still discussed. Designed for a 90-day mission, the lander operated until 1982, and the orbiter mapped the planet from above for years.