Learn
about the Viking 1 and 2 missions and Spacecraft
The Viking project consisted of launches of two
separate spacecraft to Mars. Viking 1 was launched on August 20,
1975. The second mission, Viking 2, was launched on September 9th
1975. Each spacecraft consisted of an orbiter and a lander. After
orbiting Mars and returning images used for landing site selection,
the orbiter and lander detached and the lander entered the atmosphere
and landed at the selected site. The orbiter continued imaging and
mapping the planet as well as other scientific operations from the
Martian orbit. The fully fueled spacecraft consisting of both the
lander and the orbiter is 3527 kg. However after deployment, the
lander had a mass of about 600kg and the orbiter 900kg.
Following launch and a 10 month
cruise to Mars, the orbiter began returning global images of
Mars about 5 days before orbit insertion. The spacecraft was
inserted into Mars on June 19th 1976. Directly the spacecraft
began imaging the different candidate landing sites. From these
pictures, the judgement was made on where the spacecraft should
land.
The orbiter primary mission ended at the beginning
of solar conjunction on November 5 1976. The extended mission commenced
on December 16 1976 after solar conjunction. Operations included
close approaches to Phobos in Febraury in 1977. Minor orbit adjustments
were done occasionally over the course of the mission, promarily
to change the walk rate (the rate at which the planetocentric longitude
changed with each orbit). ON August 7th 1980, Viking 1 orbiter was
running low on altitude conrol gas and its orbit was raised to prevent
the contamination of Martian surface until the year 2019. Operations
were terminated on August 17th 1980 after 1485 orbits. The total
cost for the Viking project was roughly one billion dollars.
Following launch and a 304 day
cruise to Mars, the orbiter began returning global images of
Mars about 5 days before orbit insertion. The spacecraft was
inserted into Mars on June 19th 1976. Directly the spacecraft
began imaging the different candidate landing sites. From these
pictures, the judgement was made on where the spacecraft should
land.
On July 20th, the lander separated from the orbiter.
After the separation, the rockets of the lander fired to orient
it for entry. The aeroshell with its attachable heat shield slowed
the craft as it plunged through the atmosphere. During this time,
entry science experiments were performed. At 6km altitude at about
250 m/s the 16m 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 parachutes
slowed down the lander to 60 m/s.Then the retro-rockets fired for
40 seconds until the lander reached a velocity of 2.4 m/s. The landing
rockets used 18 nozzles rockets to spread the exhaust over a wide
range of area. This kept the surface from heating to more than 1
degree Celcius and stripped away no more than 1mm or surface material.
The lander touched down at Chryse Planitia. From 85 kg of propellant,
25kg of propellant was left after the landing.
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. The Viking 1 lander was named
the Thomas Mutch Memorial Station in January 1982 in honor of the
leader of the Viking imaging team. It operated until 13 November
1982 when it faulty command sent by ground control resulted in loss
of contact.
Following launch and a 333 day
cruise to Mars, the orbiter began returning global images of
Mars about 5 days before orbit insertion. The spacecraft was
inserted into Mars on August 7th 1976. Directly the spacecraft
began imaging the different candidate landing sites. From these
pictures and the pictures from the Viking 1 spacecraft, the
judgement was made on where the spacecraft should land. The
lander was later separated from the orbiter on September 30th
1976 and landed at Utopia Planitia.
After the separation, the rockets of the lander
fired to orient it for entry. The aeroshell with its attachable
heat shield slowed the craft as it plunged through the atmosphere.
During this time, entry science experiments were performed. At 6km
altitude at about 250 m/s the 16m 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 parachutes slowed down the lander to 60 m/s. Then the retro-rockets
fired for 40 seconds until the lander reached a velocity of 2.4
m/s. The landing rockets used 18 nozzles rockets to spread the exhaust
over a wide range of area. This kept the surface from heating to
more than 1 degree Celcius and stripped away no more than 1mm or
surface material.
The Viking 2 Lander touched down about 200km west
of the crater Mie in Utopia Plantia. 22 kg of propellant was left
from landing. Due to radar misidentification of a rock o r highly
reflective surface down with one leg on a rock, tilted at 8.2 degrees.
The cameras began taking images immediately after landing. The Viking
2 operated on the surface for 1281 Mars days and was turned off
on April 11, 1980 when its batteries failed.
Following launch and a 333 day
cruise to Mars, the orbiter began returning global images of
Mars about 5 days before orbit insertion. The spacecraft was
inserted into Mars on August 7th 1976. Directly the spacecraft
began imaging the different candidate landing sites. From these
pictures and the pictures from the Viking 1 spacecraft, the
judgement was made on where the spacecraft should land. The
lander was later separated from the orbiter on September 30th
1976 and landed at Utopia Planitia.
Normal operations called for the structure connecting
the orbiter and the lander to be ejected after separation, but because
of problems with he separation the bioshield was left attached to
the orbiter. The orbit inclination was raised to 75 degrees on September
30th 1976. On December 20th 1976, the periapsis was lowered to 778km
and the orbit inclination was raised to 80 degrees. Operations included
close approaches to Deimos in October 1977. The orbiter developed
a leak in its propulsion system that vented its altitude control
gas. It was placed to a different orbit and turned off on July 25th
1978 after returning almost 16000 images in 706 orbits.
