Viking program
The Viking program of NASA was a high point in the exploration of Mars in the 1970s. The two space probes Viking 1 and 2 landed on July 20 and September 3, 1976 successfully, and sent for the first time detailed images of the surface of the red planet.
Missions
Each Viking spacecraft consisted of a mother and daughter probe. The flyby spacecraft would orbit ( orbit ) turn around Mars, then to separate the daughter of the probe and land on the surface of the planet.
- Viking 1 was launched with a titanium 3E/Centaur on August 20, 1975 by Launch Complex 41 at Cape Canaveral. An orbit around Mars, the probe reached on 19 June 1976. Daughter probe landed on July 20, 1976 in the Chryse Planitia landscape. To the Orbiter 1980 contact was maintained until 7 August, with the lander even until 11 November 1982. The lander was renamed on January 7, 1982 Thomas A. Mutch Memorial Station, according to one of the scientists involved in the project.
- Viking 2 was launched on 9 September 1975 with the same type of missile from the same launch pad and reached orbit on August 7, 1976. The landing took place on 3 September 1976 in the level of Utopia Planitia. The contact with the Orbiter held until 25 September 1978 with the lander until April 11, 1980. The lander was posthumously renamed in 2001 after the founder of the NASA Academy in Gerald Soffen Memorial Station.
Data
- Both probes started with a Titan3E/Centaur-Rakete.
- The probes had a weight of about 2900 kg, of which 2300 kg on the flyby spacecraft and 600 kg Add to piggyback probe.
- The two orbiters sent 37,000 (Viking 1) and 19,000 (Viking 2) images of the planet Mars and its moons Phobos and Deimos.
- The total mission cost about $ 1 billion.
Scientific experiments
On board the lander were three biological experiments. A fourth experiment fulfilled in addition to biological and other tasks. The experimental 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, the Martian soil with light, water and radiolabeled carbon dioxide samples were treated. It was assumed that during the existence of photosynthetic organisms drifting through the process of carbon fixation, a portion of the radiolabeled carbon dioxide would be converted into biomass. After several days of incubation, the radioactive gas was removed, and the radioactivity remaining in the sample is measured.
Labeled Release experiment (LR)
The Labeled Release Experiment was a reversal of the PR tests in principle. A sample of Martian soil was mixed with water and a radiolabeled nutrient solution. If in the sample existed breathing organisms, they should convert the nutrient solution and Others in CO2. The radioactive 14C from the nutrient solution should then be detected in the resulting gas.
Gas Exchange Experiment ( GEX)
At the Gas Exchange experiment, a soil sample was prolonged exposure to a controlled gas mixture. Periodically the composition of the gas mixture was analyzed by a gas chromatograph and detected deviations from the original composition.
Gas chromatograph - mass spectrometer ( GCMS)
The GCMS is a device which chemically separating gaseous components, and can be analyzed by a mass spectrometer. This can be the amounts and proportions of various substances determine. In the Viking Lander, the GCMS was used to determine the individual components of the Martian soil can. For this purpose, the Martian soil samples were heated to different temperatures and each escaping gases analyzed.
Results of scientific experiments
The various experiments have yielded no clear result on whether organic life exists on Mars or not. All three biological experiments observed changes that might have been caused by organic life.
LR in the experiment, a relatively strong increase of radioactive gas was measured after the radiolabeled nutrient solution was added.
By GEX, it was found a small increase in oxygen than was added to the soil sample water. The control experiment in which the soil sample was first sterilized by heat, however, showed the same behavior. In addition, the oxygen gain occurred on only the first addition of water and could not subsequently be detected despite repeated addition of water at the same soil sample.
The GCMS other hand, could demonstrate no significant amount of organic molecules in the Martian soil. The detected organic molecules came with probability bordering on certainty of the earth resulting contamination.
These results were difficult to explain and continue to provide nutrients for scientific discussions. Most scientists have now come to the conclusion that the observed results can be explained by a chemical reaction with one or more constituents of the Martian soil is best. However, there are still scientists who are convinced that indicate the results observed on organic life. At their strongest advocates heard Gilbert Levin, one of the designers of the LR experiment.
Recent research results suggest that highly reactive chemicals such as hydrogen peroxide, produced by the static electricity of the dust storms were responsible for the positive results. For the final solution of the riddle of the Viking biology experiments more missions will be able to contribute to Mars.
According to a new analysis of the data of the LR experiment with a mathematical method to be proof of life could have been successful.