A team of scientists suspect that NASA may have found organic molecules, the proof of life on Mars, 40 years ago but accidentally destroyed them.
The first U.S. mission to land a spacecraft safely on the surface of Mars was the Viking Program in 1976. It involved two identical spacecraft called the Viking landers. The landers flew together, separated, and conducted three biological experiments designed to look for possible signs of life.
The landers did not find any living organisms except for an unidentified chemical activity on the Red Planet's soil. This came as a surprise for the agency because meteorites with rich carbon materials, as well as comets, should have at least created a single form of organic material on the Red Planet. This incident had since been a scientific mystery for 40 years.
Now, a study from a team of scientists proposed that the Viking landers, when it landed on the Martian soil, impacted the first organic material that could have already been discovered at the time.
Perchlorate On Martian Soil
To conduct the study, published in the Journal of Geophysical Research on June 20, the team reviewed the data from Viking landers to check if anything was overlooked. After all, the team also strongly believed that all terrestrial living things should contain organic material, meaning the Viking landers should have discovered something in 1976.
In 2008, the spacecraft Phoenix found a salt in the Martian soil. This salt, called perchlorate, is rare on Earth but is used to make fireworks because it explodes when exposed to high temperatures.
In 2014, Mars Curiosity found organic molecules on Mars. One of the materials discovered was chlorobenzene: a molecule that is created when carbon materials are burned with perchlorate.
Now, the team of scientists suspected that two things may have happened. One — and the proposition supported by the paper's lead author — was that since the main instrument aboard the Viking landers, called the gas chromatograph-mass spectrometer or GCMS, needed to heat the Martian soil samples to find the organic matters, it also exposed the perchlorate in the soil to high temperatures.
Chris McKay, the lead author of the paper and a planetary scientist at NASA's Ames Research Center, said the Viking landers needed to heat the soil on Mars for the soil to release vapors. These vapors were the ones subjected to further analysis. McKay thinks that in heating the soil sample, the Viking landers inadvertently ignited the perchlorate, along with what "would have been" first proof of life on Mars.
The Second Possibility
Not all scientists involved in the study supported McKay's position. Melissa Guzman from the LATMOS research center in France, who is involved in the study, said she was not convinced that the chlorobenzene was formed when Viking landers heated the Mars soil. She said another possibility was that the chlorobenzene could have come from Earth aboard the NASA equipment. Guzman said there was simply no sufficient proof that Viking landers burnt the salt on the Martian soil.
Nevertheless, the final conclusion of the paper said the salt might have chlorinated any organics inside the Viking instruments after it performed its sample acquisition from Mars.
"We conclude the chlorine component of the chlorobenzene is martian, and the carbon molecule of the chlorobenzene is consistent with a martian origin, though we cannot fully rule out instrument contamination," the team concluded in the paper.