Viking 2

Chronology

Mission timeline

1. September 9, 1975, 18:39:00 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 1975-09-09T18:39:00Z. 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. As on Viking 1, the fully fueled orbiter-lander pair is given as 3527 kg on the orbiter's page and 3530 kg on the lander's, and the disagreement is recorded rather than resolved.

   Earth
2. August 7, 1976

   Orbit insertion

   Inserted into a 24.6 hr Mars orbit

   Following launch and a 333 day cruise to Mars, the Viking 2 Orbiter began returning global images of Mars prior to orbit insertion. The orbiter was inserted into a 1500 x 33,000 km, 24.6 hr Mars orbit on 7 August 1976 and trimmed to a 27.3 hr site certification orbit with a periapsis of 1499 km and an inclination of 55.2 degrees on 9 August. Imaging of candidate sites was begun and the landing site was selected based on these pictures and the images returned by the Viking 1 Orbiter. NSSDCA's launch/orbital information page for the orbiter records the same trimmed orbit as 1496.00 x 35800.00 km at 27.32 hours and 55.200°, beginning at 1976-08-09. The two pages disagree on that orbit's periapsis - 1499 km against 1496.00 km - and the disagreement is recorded rather than resolved, as this record's 3527/3530 kg launch mass already is. Their apoapsis figures are not comparable: the master catalog prints one only for the orbit before the trim.

   Mars
3. September 3, 1976, 19:39:59 UTC

   Deployment

   Lander and aeroshell separated from the orbiter

   The lander and its aeroshell separated from the orbiter on 3 September 19:39:59 UT. At the time of separation, the lander was orbiting at about 4 km/s. After separation rockets fired to begin lander deorbit. Normal operations called for the structure connecting the orbiter and lander (the bioshield) to be ejected after separation, but because of problems with the separation the bioshield was left attached to the orbiter.

   Mars
4. September 3, 1976, 22:58:20 UTC

   Landing

   Touched down in Utopia Planitia

   The Viking 2 Lander touched down about 200 km west of the crater Mie in Utopia Planitia at 47.6673 deg N latitude and 134.2809 deg E longitude at 22:58:20 UT (9:49:05 a.m. local Mars time.) Due to radar misidentification of a rock or highly reflective surface, the thrusters fired an extra time 0.4 seconds before landing, cracking the surface and raising dust. The lander settled down with one leg on a rock, tilted at 8.2 degrees. The cameras began taking images immediately after landing. 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 Utopia Planitia at 22:37:50 UT. This record follows the lander's own page, which the lander's launch/orbital information page corroborates with a Lander epoch beginning 1976-09-03 22:58:20.

   Mars
5. September 30, 1976

   Milestone

   Orbit inclination raised to 75 degrees

   The orbit inclination was raised to 75 degrees on 30 September 1976. The orbiter primary mission ended at the beginning of solar conjunction on 8 November 1976, and the extended mission commenced on 14 December 1976 after solar conjunction. On 20 December 1976 the periapsis was lowered to 778 km and the inclination raised to 80 degrees.

   Mars
6. October 23, 1977

   Milestone

   Periapsis lowered to 300 km after close approaches to Deimos

   Operations included close approaches to Deimos in October 1977 and the periapsis was lowered to 300 km and the period changed to 24 hours on 23 October 1977. NSSDCA's launch/orbital information page for the orbiter records the resulting orbit as a periapsis of 300.00 km at 24.00 hours from 1977-10-23.

   Mars
7. July 25, 1978

   Milestone

   Orbiter turned off after 706 orbits

   The orbiter developed a leak in its propulsion system that vented its attitude control gas. It was placed in a 302 x 33176 km orbit and turned off on 25 July 1978 after returning almost 16,000 images in 706 orbits around Mars. NSSDCA's launch/orbital information page for the orbiter prints a Decay Date of 1978-07-25 and the same 302.00 x 33176.00 km orbit, though it dates that orbit's epoch start to 1980-07-24, two years after the shutdown the master catalog describes; the disagreement is recorded rather than resolved.

   Mars
8. April 11, 1980

   Mission end

   Lander turned off after 1281 Mars days

   The Viking 2 Lander operated on the surface for 1281 Mars days and was turned off on April 11, 1980 when its batteries failed. NSSDCA's launch/orbital information page for the lander ends its Lander epoch at 1980-04-11 00:00:00. The lander's master catalog page lists Gerald Soffen Memorial Station among its alternate names.

   Mars

Mission architecture

Vehicles

• Viking Orbiter 2 · Orbiter

  Destinations: Mars

  • Viking Lander 2 · Lander

    Destinations: Mars