The Complete Book of Spaceflight: From Apollo 1 to Zero Gravity

Viking 1 and 2
Twin spacecraft that studied Mars both from orbit and on
the surface, and carried out the first in situ experiments
to look for life on another world. Each Viking consisted
of an orbiter and a lander. After arrival in orbit around
the planet on June 19 and August 7, 1976 (Viking 1 having
departed second but arrived first), a detailed reconnaissance
was carried out to identify suitable and safe
landing sites, during which the United States celebrated
its bicentennial. Subsequently, the Viking 1 lander
touched down in the western part of Chryse Planitia (the
Plains of Gold), followed by its sister craft 7,420 km to
the northeast.
The orbiter was an enlarged version of the Mariner 9
spacecraft and carried scientific instruments on a scan
platform, the most important of which were two television
cameras to photograph potential landing sites. The
lander was a hexagonal box with four landing legs, each
with a circular footpad. On top of the body were two TV
cameras, a mast supporting meteorological experiments,
two small nuclear power systems, a dish-shaped radio
antenna, and a robot arm used to sample the surface.
Inside the body was a package of three biology experiments.
During the flight to Mars, the lander, inside a protective
shell, was attached to the orbiter by a truss structure.
The shell included an outer biological shield to prevent
terrestrial microbes from contaminating Mars and a
clamlike aeroshell to protect the lander during entry into
the Martian atmosphere. The automated landing sequence
began when the lander was separated from the orbiter
and fired thrusters on its aeroshell to start entry. Two
hours later, the aeroshell plunged into the thin Martian
air. A parachute opened at a height of 6,200 km and
released at 1,200 m to enable the craft to touch down
gently using its three braking thrusters. Minutes after
landing, Viking 1 sent back the first pictures from the surface
of Mars.
The results of the biological experiments were intriguing
but inconclusive. Activity such as would be expected
of microbes was found in some of the tests, but an instrument
known as a gas chromatograph mass spectrometer,
used to search for organic material, found none. The last
data received from the Viking 2 lander was on April 11,
1980, and contact with the other lander was lost on
Viking Missions
Villafranca Satellite Tracking Station (VILSPA) 469
Viking A technician checks the soil sampler of the Viking
lander. NASA
November 11, 1982, after it had been accidentally sent a
wrong command. (See table, “Viking Missions.”)
Launch
Vehicle: Titan IIIE
Site: Cape Canaveral
Dry mass, orbiter + lander: 600 kg
Villafranca Satellite Tracking Station (VILSPA)
Part of ESA’s (European Space Agency’s) worldwide
ESOC (European Space Operations Centre) Station
Network (ESTRACK). VILSPA lies in the Guadarrama
Valley, 30 km west of Madrid. Built in 1975, it supports
many ESA and other international programs, including
IUE, OTS 2, GOES 1, MARECS, Exosat, and ISO.
Spacecraft Launch Date Landing Date Location
Viking 1 Aug. 20, 1975 Jul. 20, 1976 Chryse Planitia 22.4° N, 47.5° W
Viking 2 Sep. 9, 1975 Sep. 3, 1976 Utopia Planitia 48° N, 226° W