Lesson 4 of 5 · Viking
Viking: connect an orbital survey to surface laboratories
8 minute lesson · 3 checks along the way
Your goal for this lessonExplain Viking’s landing decisions, paired architecture and cautious interpretation of life-detection experiments.
In this lesson 3 sections · 3 checks
Using archive links & definitions
Follow a linked name to explore its archive card. “Back to your lesson” brings you to the same part of the reading.
Words with a dotted underline open a short definition right here in the lesson.
Read & understand
Send two coordinated investigations to Mars
NASA’s Viking project launched two spacecraft in 1975, each combining an orbiter and a lander. Langley Research Center managed the project; JPL developed the orbiters and supported mission operations, while Martin Marietta built the landers. The architecture connected a view of the planet from above with detailed measurements at two places on the ground.
The orbiters photographed Mars and helped assess landing areas before the landers separated. Original site choices were revised when closer observations revealed hazards. This turned orbital into an operational decision: a scientifically interesting location also had to be a place where the spacecraft could arrive and operate safely.
Check 1 of 3
10 pointsUse the reading above. You can try again without losing points.
Read & understand
A protected descent delivers a working laboratory
Viking 1 landed at Chryse Planitia on July 20, 1976; Viking 2 reached Utopia Planitia on September 3. Entry protection, parachutes and powered descent worked in sequence. The landers then used cameras, weather instruments and sampling equipment to investigate their surroundings. The ground photograph of Viking 1 shows the assembled orbiter and enclosed lander before their paths separated.
Solar panels powered the orbiters, while radioisotope generators powered the surface vehicles. Communication links and the Deep Space Network connected the measurements to teams on Earth. The spacecraft returned observations well beyond the initial mission period, allowing changes in weather and surface appearance to be followed at the landing sites.
NASA’s 1975 ground photograph shows Viking 1 with its orbiter and enclosed lander assembled before launch. The solar panels, antennas and connected elements illustrate a configuration that later separated into orbital and surface investigations. This is not a view of the spacecraft flying above Mars.
Look closely
Why does the assembled photograph not imply that the orbiter landed with the surface laboratory?
See what to notice
The elements traveled together before separation, then performed different tasks. Their later trajectories and functions are established by the mission record.
Check 2 of 3
10 pointsUse the reading above. You can try again without losing points.
Read & understand
An experiment response needs an explanation
The landers carried biology experiments intended to test for possible signs of life in samples. Their responses had to be considered alongside organic analysis, instrument behavior and possible nonbiological soil chemistry. The investigations did not establish definitive evidence of Martian life; an intriguing response in one experiment was not sufficient by itself to settle the interpretation.
That conclusion is also narrower than proving that life never existed anywhere on Mars. Two surface sites and a particular set of experiments have limited reach. Viking’s images, atmospheric records and laboratory results substantially expanded the evidence available for later missions. Its enduring contribution includes both the observations and a clear example of how difficult a life-detection claim can be to establish.
Check 3 of 3
10 pointsUse the reading above. You can try again without losing points.
Put it together
Your lesson progress
Each check connects to a part of the story. Complete all 3 to earn your 25-point lesson bonus.
Explore further · Optional
Go to the source
Explore the evidence behind this lesson. These optional readings and videos open in a new tab.
- Read: NASA: Viking’s paired orbiters and landersCompare the explanation and its assumptions with the worked example in this lesson.
- Read: NASA: Viking project instruments and archived dataCompare the explanation and its assumptions with the worked example in this lesson.
- Read: NASA: Viking 1’s landing, operations and science limitsCompare the explanation and its assumptions with the worked example in this lesson.