Mars Academy

Viking 1 Orbiter Chronology

Date          Revolution Event

June 19, 1976 0 Mars orbit insertion

June 21, 1976 2 Trim to plan site certification orbit

July 9, 1976 19 Orbit trim to move westward

July 14, 1976 24 Synchronous orbit over landing site

July 20, 1976 30 VL-1 landing

August 3, 1976 43 Minor orbit trim to maintain
synchronization

Sept. 3, 1976 75 VL-2 landing

Sept. 11, 1976 82 Decrease of orbit period to begin
eastward walk

Sept. 20, 1976 92 Orbit trim to permit synchronization
over VL-2

Sept. 24, 1976 96 Synchronous orbit over VL-2

Jan. 2, 1977 213 Period change to approach Phobos

Feb. 4, 1997 227 Orbit synchronization with Phobos
period

Feb. 12, 1977 235 Precise correction to Phobos
synchronization

March 11, 1977 263 Reduction of periapsis to 300 km.

March 24, 1977 278 Adjustment of orbit period to 23.5
hours

May 15, 1977 331 Phobos avoidance maneuver

July 1, 1977 379 Adjustment of period to 24 hours

Dec. 2, 1978 898 Adjustment of orbit period to 24.85
hours; beginning of small walk around
the planet

May 19, 1978 1061 Adjustment of orbit period to 25.0
hours; acceleration of walk rate

July 20, 1979 1120 Raising of periapsis to 357 km.
Adjustment of orbit period to 24.8
hours and slowing of walk rate.