Until now, the methods available to earthlings for analyzing ancient basalts made it difficult to identify past microbial life.
Since the 1960s, after the return of Earth vehicles from other celestial bodies (the Moon), NASA has practiced quarantines: strict isolation of returned people and materials for a certain period of time. Behind this was a very exotic, from the point of view of biology, the idea that extraterrestrial microbes could cause an epidemic on Earth. At the same time, it was believed that terrestrial life could displace extraterrestrial life in its original habitat.
Space experts, including former NASA employees, point out that it is for these reasons that the agency has avoided sending automatons capable of detecting modern life to Mars since 1976. And those vehicles that were nevertheless sent to the fourth planet deliberately did not carry equipment to detect existing life — only traces of the past.
Therefore, when NASA planned to return samples of Martian rocks collected by the Perseverance rover, a dilemma arose. The same "safety" standards prevented us from simply bringing samples here and examining them. It was required that the tools for such analysis could be placed in a biolab with the fourth level of protection. This seriously limited the possibilities of exploring the returned soil.
An international team of researchers has developed a method to find traces of ancient microbes, even while remaining in the Procrustean bed of NASA regulations. They applied microscopic examination based on Fourier spectroscopy of infrared radiation to identify traces of life in the basalts. The results are published in the International Journal of Astrobiology.
First, the developers tried to find traces of microbial cells in a 100 million-year-old basalt sample using standard analytical methods. Basalt was chosen because it is part of the Perseverance samples. It turned out that standard methods that require compact equipment cannot detect traces of life in basalt, although more sophisticated methods have, of course, found such traces. These more effective methods themselves were not far from ideal either: they not only involved not always compact equipment, but often led to the destruction of the analyzed samples.
Then the scientists used optical photothermal infrared spectroscopy. It helped both to find traces of terrestrial life in terrestrial samples, and did not require strong crushing of the analyzed piece of basalt. This method required irradiating the surface under study with infrared radiation, and then firing it with a laser with a wavelength corresponding to green. This made it possible to distinguish parts up to 0.5 micrometers in size with fairly moderate damage to the samples.
The results of the analysis of thin basalt flakes by a new method
Image source: Yohey Suzuki et al.
The method may be one of the latest developed for this type of analysis. The fact is that the NASA standards described above make manned flights to Mars almost impossible. Due to the recent leadership change of the National Aeronautics and Space Administration of the United States and other political changes in the country, such restrictions will almost certainly be lifted. This means that samples of Martian rocks returned to Earth will be able to be studied by a variety of methods, not limited to rooms with the fourth level of biosecurity.
