Viking 1

Chronology

Mission timeline

1. August 20, 1975, 21:22:00 UTC

   Launch

   Launched on a Titan IIIE-Centaur

   NSSDCA's launch/orbital information pages for both the orbiter and the lander give the launch date and time as 1975-08-20T21:22:00Z. The Viking project consisted of launches of two separate spacecraft to Mars, Viking 1, launched on 20 August 1975, and Viking 2, launched on 9 September 1975. The fully fueled orbiter-lander pair had a mass of 3527 kg on the orbiter's page and 3530 kg on the lander's; the disagreement is recorded rather than resolved. The lander was encased in a bioshield at launch to prevent contamination by terrestrial organisms.

   Earth
2. June 19, 1976

   Orbit insertion

   Inserted into Mars orbit after a 10 month cruise

   Following launch and a 10 month cruise to Mars, the orbiter began returning global images of Mars about 5 days before orbit insertion. The Viking 1 Orbiter was inserted into Mars orbit on 19 June 1976 and trimmed to a 1513 x 33,000 km, 24.66 hr site certification orbit on 21 June. Imaging of candidate sites was begun and the landing site was selected based on these pictures. The lander's page describes the same cruise as 304 days. NSSDCA's launch/orbital information page for the orbiter records the same trimmed orbit as 1510.00 x 32600.00 km at 24.66 hours and 37.900°, beginning at 1976-06-21. The two pages disagree on both distances - 1513 x 33,000 km against 1510.00 x 32600.00 km for one orbit of the same 24.66 hr period - and the disagreement is recorded rather than resolved, as this record's 3527/3530 kg launch mass already is.

   Mars
3. July 20, 1976, 08:51 UTC

   Deployment

   Lander and aeroshell separated from the orbiter

   The lander and its aeroshell separated from the orbiter on 20 July 08:51 UT. At the time of separation, the lander was orbiting at about 4 km/s. After separation rockets fired to begin lander deorbit. After a few hours at about 300 km altitude, the lander was reoriented for entry.

   Mars
4. July 20, 1976, 11:53:06 UTC

   Landing

   Touched down in western Chryse Planitia

   The Viking 1 Lander touched down in western Chryse Planitia at 22.27 deg N latitude and 312.05 deg E longitude (planetocentric) at 11:53:06 UT (4:13 p.m. local Mars time). At 6 km altitude at about 250 m/s the 16 m diameter lander parachutes were deployed; seven seconds later the aeroshell was jettisoned, and 8 seconds after that the three lander legs were extended. In 45 seconds the parachute had slowed the lander to 60 m/s, and at 1.5 km altitude retro-rockets were ignited and fired until landing 40 seconds later at about 2.4 m/s. Transmission of the first surface image began 25 seconds after landing. The seismometer failed to uncage, and a sampler arm locking pin was stuck and took 5 days to shake out; otherwise, all experiments functioned nominally. NSSDCA's two master catalog pages do not reconcile on this time and the disagreement is recorded rather than resolved: the orbiter's page says the lander landed at Chryse Planitia at 11:56:06 UT. This record follows the lander's own page, which the lander's launch/orbital information page corroborates with a Lander epoch beginning 1976-07-20 11:53:06.

   Mars
5. November 5, 1976

   Milestone

   Primary mission ended at solar conjunction

   The orbiter primary mission ended at the beginning of solar conjunction on 5 November 1976. The extended mission commenced on 14 December 1976 after solar conjunction.

   Mars
6. March 11, 1977

   Milestone

   Periapsis reduced to 300 km after close approaches to Phobos

   Operations included close approaches to Phobos in February 1977. The periapsis was reduced to 300 km on 11 March 1977. Minor orbit adjustments were done occasionally over the course of the mission, primarily to change the walk rate - the rate at which the planetocentric longitude changed with each orbit, and the periapsis was raised to 357 km on 20 July 1979.

   Mars
7. August 17, 1980

   Milestone

   Orbiter operations terminated after 1485 orbits

   On 7 August 1980 Viking 1 Orbiter was running low on attitude control gas and its orbit was raised from 357 x 33943 km to 320 x 56000 km to prevent impact with Mars and possible contamination until the year 2019. Operations were terminated on 17 August 1980 after 1485 orbits. NSSDCA's launch/orbital information page for the orbiter prints a Decay Date of 1980-08-17 and a final orbit of 320.00 x 56000.00 km at 47.26 hours beginning 1980-08-07.

   Mars
8. November 13, 1982

   Mission end

   Contact with the Thomas Mutch Memorial Station lost

   The Viking 1 Lander was named the Thomas Mutch Memorial Station in January 1981 in honor of the original leader of the Viking imaging team. It operated until 13 November 1982 when contact was lost. NSSDCA's launch/orbital information page for the lander ends its Lander epoch at 1982-11-13 00:00:00.

   Mars

Mission architecture

Vehicles

• Viking Orbiter 1 · Orbiter

  Destinations: Mars

  • Viking Lander 1 · Lander

    Destinations: Mars