Organics on Mars could have been discovered 40 years ago if a different method of analysis were used.
The other day in the journal in the journal JGR: Planets. an article was published, the authors of which believe that organics on Mars could have been discovered 40 years ago. Could be, but was not - because the methods of soil analysis used by the probes of the "Viking" series , led to the destruction of traces of organic compounds in the samples taken.
“The complete absence of traces of organic matter in the samples collected by Viking-1 and Viking-2 was a surprise, since this contradicted scientists’ ideas about what could be found on planets and asteroids. But we understood what the problem was after we found traces of perchlorates, ”said Christopher McKay from NASA Ames Research Center (USA).
For many years, scientists have been arguing about where and in what quantities organic matter can accumulate in the soil of Mars. Scientific discussions touch upon the question of the existence of liquid water and relatively warm areas in the ground. All this is connected with the main issue - the possibility of life on the Red Planet.
A few years ago, liquid water was discovered on Mars, and traces of a warmer climate were found in the distant past of the planet. Well, in June, the Curiosity rover team announced that scientists were able to detect reserves of complex ancient organic matter in one of the cobblestones on the slope of Mount Sharp . Namely - in the crater Gale, now the rover works here.
But since there is organic matter on Mars, and it is not very rare, why did not the Viking series vehicles - the Viking-1 and Viking-2 landing modules - discover it? They were very perfect for their time. Thanks to the efforts of the developers, these systems were able to sink to the surface of Mars in 1976 and 1978. They also transmitted to the Earth photographs of the surface of Mars and information about the analysis of the soil and its composition. These were the data, so to speak, "first-hand." The Vikings had sensors of organic substances, as well as a set of tools and reagents that made it possible to search for traces of living organisms in the soil of the Red Planet.
As mentioned above, no Viking organics were found, which greatly surprised scientists. Planetologists of the time believed that there must be a large amount of organic matter on Mars - at least one that was brought by asteroids and comets. After all the data were obtained, the scientists began to argue about where the indicated compounds had gone. According to some experts, they were destroyed by high-energy cosmic rays, as well as ultraviolet radiation. In addition, scientists say there is a large amount of perchlorate in the soil of Mars. These are quite aggressive compounds that destroy many substances.
Curiosity could detectorganic, because the system used other methods of studying soil samples. But why the developers of the "Vikings" used the method of analysis, which led to the destruction of organic matter with a 100% result? The authors of the publication, which was mentioned above, was able to answer this question. The fact is that the scientists who developed and launched the Vikings were simply not aware of the fact that there are perchlorates in the soil of the Red Planet. They, by the way, were discovered for the first time by the Phoenix module in 2008.
Since perchlorates are chemically active, they easily react with organic compounds, which leads to the destruction of the latter. As far as can be judged, the heating of samples of Martian soil in the Viking pits led to the beginning of a chain of chemical reactions between perchlorates and organic matter, as a result of which the latter was destroyed.
The researchers, who published the article indicated at the beginning of the post, proved their point of view with the help of a contented simple experience. They simply heated a mixture of perchlorates and organics. Then the results of the “experiment” were studied. It turned out all traces of organic matter disappeared. Chlorobenzene was released as a by-product. And that's just what his "Vikings" found - in all samples of the soil of Mars, which were analyzed. Most likely, these probes completely destroyed all traces of organic matter, which was contained in the samples. And this annoying mistake has delayed the discovery of organic matter on Mars by as much as 40 years, almost half a century.