October 30, 2015 at 16:40Amino acids in samples of lunar soil were from the Earth
NASA says that traces of organic matter that were found in samples of lunar soil obtained during the Apollo missions are of terrestrial origin. The research team, which had seven soil samples stored in NASA, conducted their chemical analysis using modern methods that were not available in the 70s of the last century. The concentration of found amino acids is very low (ranges from 105 to 1910 parts per billion), and several types of analysis were used to establish their origin.
Several types of carbon isotopes were found in the soil. It is known that amino acids of terrestrial origin have carbon-12 in their composition, since it easily enters the necessary chemical reactions. The concentration of the heavier carbon-13 isotope, which is attributed to the composition of amino acids of abiogenic origin, turned out to be characteristically lower than the concentration of carbon-12. Due to this difference, it was concluded that the lighter carbon isotope was introduced into the Earth.
However, doubts arose. If we assume that the solar wind is a factor in the formation of amino acids, then their concentration should decrease in those parts of the soil that were taken from a greater depth of the lunar surface. However, the analysis showed exactly the opposite - the concentration of amino acids increased with depth, from where the sample was taken. Also, the hypothesis that the cause of the formation of amino acids was exhaust from the engines of landing modules was also doubtful. Soil samples taken 6.5 km from the Apollo 17 landing site contained approximately the same concentration of amino acids as those taken directly on site.
Therefore, to determine the origin of the substances found, a different type of analysis was used. It is known that amino acid molecules of biological origin have left asymmetry, while in laboratory synthesis molecules with an approximately equal proportion of asymmetry are obtained. After the corresponding analysis, it was revealed that the vast majority of the amino acids found had left asymmetry, which made it possible to connect their origin with the earth. Traces of alpha-aminoisobutrylic acid, which is extremely rare for the Earth, were also identified, which, according to researchers, could be brought into the ground by meteorites.
Several types of carbon isotopes were found in the soil. It is known that amino acids of terrestrial origin have carbon-12 in their composition, since it easily enters the necessary chemical reactions. The concentration of the heavier carbon-13 isotope, which is attributed to the composition of amino acids of abiogenic origin, turned out to be characteristically lower than the concentration of carbon-12. Due to this difference, it was concluded that the lighter carbon isotope was introduced into the Earth.
However, doubts arose. If we assume that the solar wind is a factor in the formation of amino acids, then their concentration should decrease in those parts of the soil that were taken from a greater depth of the lunar surface. However, the analysis showed exactly the opposite - the concentration of amino acids increased with depth, from where the sample was taken. Also, the hypothesis that the cause of the formation of amino acids was exhaust from the engines of landing modules was also doubtful. Soil samples taken 6.5 km from the Apollo 17 landing site contained approximately the same concentration of amino acids as those taken directly on site.
Therefore, to determine the origin of the substances found, a different type of analysis was used. It is known that amino acid molecules of biological origin have left asymmetry, while in laboratory synthesis molecules with an approximately equal proportion of asymmetry are obtained. After the corresponding analysis, it was revealed that the vast majority of the amino acids found had left asymmetry, which made it possible to connect their origin with the earth. Traces of alpha-aminoisobutrylic acid, which is extremely rare for the Earth, were also identified, which, according to researchers, could be brought into the ground by meteorites.