Multiple lab analyzes of Antarctic minerals provide a better understanding of Mars

Results from multiple and complementary lab analyzes of minerals found in samples of material from Antarctica could give scientists a better understanding of Mars’ surface and subsurface environments, and could pinpoint the locations of potentially habitable subterranean sites, says a new Planetary paper. Science Institute Research Scientist Elizabeth C. Sklute.

Samples from intermittent brine discharge at Blood Falls at the terminus of Taylor Glacier, Antarctica, were collected by Jill Mikucki of the University of Tennessee, Knoxville over two field seasons. The brine flows from an underground body of water that has been isolated for thousands of years. The brine flow deposits material that [is the] surface manifestation of a subterranean environment harboring a thriving community of microbial life. Initially, the brine is clear, but the deposits turn red on the surface over time, giving Blood Falls its name. These surface samples were tested in Sklute’s lab using Fourier transform infrared, Raman, visible to near infrared, and Mössbauer spectroscopies. Samples were further characterized using microprobe and inductively coupled plasma optical emission spectroscopy for chemistry and X-ray diffraction, scanning electron microscopy and transmission electron microscopy for mineralogy, crystallography and chemistry.

“We took dry samples and analyzed them by shining light of different wavelengths on them. Each wavelength of light causes the bonds and atoms in a sample to react in a different way. By using them all together, we can find out what there is,” said Sklute, lead author of “A Multi-Technique Analysis of Surface Materials From Blood Falls, Antarctica” appearing in Frontiers in astronomy and space science†

“We take each of these little bits of information and we stitch them together to make a whole picture, because one technique can be really good at telling you if certain things are there and another technique can miss it completely, simply because the bonds or atoms don’t react to those energies,” Sklute said. “These results demonstrate the strengths and weaknesses of different analytical methods and underscore the need for multiple complementary techniques to inform the complicated mineralogy at this site.

“By combining these techniques, we determined the detailed mineralogical assemblage of this Mars analog site and learned that the deposit is mainly carbonates and that the red color of Bloody Falls comes from the oxidation of dissolved ferrous ions (Fe2+ ) while exposed in the air, probably in combination with other ions. Instead of forming iron (Fe3+) minerals, which usually happens on Earth, this brine turns into amorphous (not a long-range structure) nanospheres containing iron and a lot of other contain elements, such as chlorine and sodium.Amorphous materials have been found ubiquitously in Gale Crater on Mars through the Curiosity rover,” Sklute said. “Until now, we haven’t been able to determine what the amorphous material on Mars is made of. It’s really exciting to find what similar material might be in a natural environment on Earth.

“We’re not saying this is a biosignature, because it’s not produced by the microbes, but rather by the chemistry where the microbes live. However, it gives us a roadmap for a place to look at another frozen world,” Sklute said. .

“The method we used in this study will also provide us with a powerful tool to help us understand how things might change over time when they return from another planet. It helps us understand variability in phases that are really below the detection limit of most common techniques,” Sklute said.

PSI Senior Scientist M. Darby Dyar is a co-author of the paper.