The Truth About the Apollo Lunar Samples
In October of last year NASA released the findings of a study that examined the Apollo lunar samples taken during the Apollo missions of the late 1960’s and early 1970’s. Despite the belief that there was no life on the moon, the Apollo mission soil samples taken over four decades ago contained traces of amino acids – the building materials of proteins. At the time, this was one of the most perplexing finds of the missions. The NASA scientists in the study from last year determined that these amino acids came from Earth, not the moon, closing out the mystery.
Amino Acids on Earth and In Space
Amino acids are the building components for proteins. Proteins make it possible for all cellular processes to take place. Out of 20 different types of amino acids, humans can produce 10 in our bodies. The 10 that we cannot produce we must get through our diet, and are known as the essential amino acids.
In relation to the Apollo lunar samples, we know that amino acids can structurally come in 2 shapes. These shapes are mirror images of each other (imagine your left and right hands). Amino acids are either “lefties” or they are “righties”. On Earth, amino acids primarily take the “lefties” shape.
Furthermore, elements such as carbon, which are found in amino acid molecules, take many different forms. We call different versions of an element an isotope. In this case, life prefers to use Carbon-12, and is thus found in abundance on Earth. Carbon-13 is found more often in non-biological matter, such as that found on asteroids.
Nullifying the Old Theories
In October of 2015 the NASA scientists addressed several prevailing theories about the origins of the amino acids on the moon. One theory was that the amino acids could have come from solar wind. Next, they could have come from the exhaust of the spacecraft that landed on the moon. They could also have come from asteroids that impact the moon frequently. Or finally they could have come from contamination by interaction with life on Earth.
The scientists found were able to rule out 3 of the above 4 theories. They ruled out solar wind by explaining that if solar wind was the source, there should have been higher concentrations of the amino acids on the surface soil samples than there were in the samples from under the surface. This was not the case.
They ruled out the spacecraft exhaust theory by reasoning that if the amino acids came from the exhaust, there would be a higher concentration of amino acids nearer to the ship than farther away. Once again, the samples contained in the lab did not confirm this. Samples taken from 4 miles away did not contain less amino acid molecules.
Finally, the team nullified the asteroid impact theory by using their knowledge of the isotope qualities of Carbon. As discussed above, Carbon-13 is found in asteroids and meteorites, while Carbon-12 is found in biological matter on Earth. The team found a majority of Carbon-12 in the samples. This confirmed that while some of the amino acids did come from asteroids, the majority would have come from Earth.
A Mystery Solved
After addressing each of the other theories, the team confirmed that the amino acids were from Earth by examining their “left” or “right” orientation. The amino acids were all “lefties”, which made them a match for those on Earth.
Thus these scientists have put to rest a decades-old puzzle concerning the Apollo lunar samples. This was only possible due to the modern technological capabilities of today’s research facilities. The conclusion that the amino acids came from human contamination gives future exploration missions a valuable insight and lesson, and illustrate the need for even more care to be taken when handling samples.