Viking orbiter during lander detachment
|Launcher||Titan 3E / Centaur|
|Takeoff mass||2900 kg|
|Course of the mission|
|Start date||August 20, 1975 (Viking 1)
September 9, 1975 (Viking 2)
|End date||July 25, 1978 (Orbiter V. 2)
April 11, 1980 (Lander V. 2)
August 17, 1980 (Orbiter V. 1)
November 13, 1982 (Lander V. 1)
The Viking program of NASA was a high point in the exploration of Mars in the 1970s. The two Viking 1 and 2 space probes landed successfully on July 20 and September 3, 1976 and for the first time sent detailed images of the surface of the red planet.
Landing sites of the two Viking probes
Each Viking probe consisted of a mother and daughter probe. The flyby spacecraft should one orbit ( orbit strike) around Mars, after the daughter probe should detach and on the surface of the planet land.
- Viking 1 was launched on August 20, 1975 from Launch Complex 41 on Cape Canaveral with a Titan 3E / Centaur . The probe reached an orbit around Mars on June 19, 1976. The daughter probe landed on July 20, 1976 in the Chryse Planitia landscape . The orbiter was kept in contact until August 17, 1980, with the lander even until November 13, 1982. The lander was renamed the Thomas A. Mutch Memorial Station on January 7, 1982 , after one of the scientists involved in the project.
- Viking 2 was launched on September 9, 1975 with the same type of rocket from the same launch pad and reached its orbit on August 7, 1976. Landing took place on September 3, 1976 in the Utopia Planitia plain . Contact with the orbiter lasted until July 25, 1978, and the lander until April 11, 1980. In 2001, the lander was posthumously renamed Gerald Soffen Memorial Station after the founder of the NASA Academy .
- Both probes started with a Titan 3E Centaur rocket.
- The probes weighed around 2,900 kilograms, of which 2,300 kg were accounted for by the mother probe and 600 kg by the daughter probe.
- The two orbiters transmitted 37,000 (Viking 1) and 19,000 (Viking 2) images of the planet Mars and its moons Deimos and Phobos .
- The countries each sent around 2,300 images.
- The entire mission cost about a billion dollars .
There were three biological experiments on board the lander. A fourth experiment fulfilled other tasks besides biological ones. The experiment package weighed 15.5 kg and had an average electrical power consumption of 15 watts.
Pyrolytic Release Experiment (PR)
The Pyrolytic Release experiment should look for traces of photosynthesis . For this purpose, samples from the Martian soil were treated with light, water and radioactively labeled carbon dioxide. It was assumed that if photosynthesis-inducing organisms existed, part of the radioactively labeled carbon dioxide would be converted into biomass by the process of carbon dioxide fixation . After an incubation period of several days , the radioactive gas was removed and the remaining radioactivity in the sample was measured.
Labeled Release Experiment (LR)
The Labeled Release Experiment was, in principle, a reverse of the PR test. A sample of the Martian soil was mixed with water and a radioactively labeled nutrient solution. If breathing organisms existed in the sample , these should include the nutrient solution. convert to CO 2 . The radioactive 14 C from the nutrient solution should then be detectable in the resulting gas.
Gas Exchange Experiment (GEx)
In the gas exchange experiment, a soil sample was exposed to a controlled gas mixture for a long time. The composition of this gas mixture was examined at regular intervals using a gas chromatograph and deviations from the original composition were determined.
Gas Chromatograph - Mass Spectrometer (GCMS)
The GCMS is a device that chemically separates gaseous components and allows them to be analyzed by a mass spectrometer . This can be used to determine the quantities and proportions of various substances. In the Viking lander, the GCMS was used to determine the individual components of the Martian soil. For this purpose, samples from the Martian soil were heated to different temperatures and the gases released in each case were analyzed.
Results of the scientific experiments
In the LR experiment, a relatively large increase in radioactive gas could be measured after the radioactively labeled nutrient solution was added.
A small increase in oxygen was observed by the GEX as water was added to the soil sample. The control experiment in which the soil sample was first sterilized by heat , however, showed the same behavior. In addition, the increase in oxygen only occurred the first time water was added and could no longer be detected afterwards, despite the addition of water to the same soil sample.
On the other hand, the GCMS could not detect any significant amount of organic molecules in the Martian soil. The detected organic molecules came with a probability bordering on certainty from contaminants created on earth.
These results were difficult to explain and continue to provide nutrients for scientific discussion. Most scientists have now come to the conclusion that the observed results can best be explained by a chemical reaction with one or more constituents of the Martian soil. Research suggests that highly reactive chemicals such as B. Hydrogen peroxide , produced by the static electricity of the dust storms, for which positive results were responsible. However, there are still scientists who are convinced that the results observed point to organic life. One of its strongest supporters is Gilbert Levin , one of the designers of the LR experiment. Further missions to Mars will be able to contribute to the final solution to the riddle of the Viking biology experiments.
After a new analysis of the data from the LR experiment using a mathematical method, his proof of life could have been successful.
Whereabouts of the probes
With the High Resolution Imaging Science Experiment (HiRISE) of the Mars Reconnaissance Orbiter (MRO), NASA was able to take photos of the landing sites of the Viking probes, on which the landing modules can be seen. The Viking 1 lander was six kilometers away from the planned landing site. Viking 1's orbiter was launched into higher orbit 10 days before it was shut down in 1980, avoiding an impact before 2019. In 2014, both orbiters were still in orbit around Mars.
- Bruno Stanek, Ludek Pesek: Neuland Mars, exploration of a planet , Hallwag Verlag, Bern and Stuttgart (1976) ISBN 3-444-10197-X
- The Viking Mission
- NASA Viking page (English)
- Marsdaily.com new research results (English)
- Photo of the Viking landing positions on Mars (JPEG, 3.8 megabytes )
- First close up the surface of Mars (English)
- The entire Viking team: The Martian Landscape , Scientific and Technical Information Office, National Aeronautics and Space Administration, Washington, DC (1978), NASA-SP-425, at NASA History Online
- Carr, MH; Tree, WA; Blasius, KR; Briggs, GA; Cutts, YES; Duxbury, TC; Greeley, R .; Guest, J .; Masursky, H .; Smith, BA, et al., Viking orbiter views of Mars , Scientific and Technical Information Branch, National Aeronautics and Space Administration, Washington, DC (1980), NASA-SP-441, at NASA History Online
- Searching for Life on Mars: The Development of the Viking Gas Chromatograph Mass Spectrometer (GCMS) ( Memento from February 2, 2007 in the Internet Archive ) (PDF)
- Gilbert V. Levin: I'm Convinced We Found Evidence of Life on Mars in the 1970s . October 10, 2019 in Scientific American
- Dirk Lorenzen and Monika Seynsche : News from the Green Men , Deutschlandfunk - research current April 18, 2012, accessed: April 18, 2012
- Has the HiRISE camera ever photographed the Viking Lander? What happened to the Viking orbiters? Astronews.com, accessed June 1, 2014