Fast assessment of mineral content on Martian-like soil with portable XRF device
This experiment is about testing an innovative way to analyze Martian soil composition. At the MDRS, our goal is to provide a rapid and reliable assessment of Martian-like soil mineral content, which will contribute (i) to evaluate the suitability of these soils for food production and (ii) to study the potential ancient presence of liquid water pathway. To meet this objective, we will use a portable X-ray fluorescence (pXRF) device, already used for terrestrial soil mineral content analysis. Thanks to its portability, its large range of mineral detection or even its rapidity, the pXRF seems to show powerful advantages to tackle questions still unanswered about Martian soil surface composition. Our experiment will implement the guidelines to reproduce these measurements on Mars in coming decades and its actual mineral content, at a small-scale.
The experience we will lead at the MDRS is the study of mineral content of Martian-like soils. We would like to test a rapid and reliable method, already use for terrestrial soils, in order to assess the mineral content of Martian-like soil surface.
This will fulfill two sub-questions we address:
(1) How suitable the martian soils are for food production?
Because of their essential role in Human survival, soil quality on Earth is highly studied all around the world. Indeed, soil contamination with metals or toxic components may have dangerous consequences on Human health. In a context of Mars colonization, if someday people are expected to live on Mars, could they rely on a “local” food production? Do those soils contain the minimal required concentration of essential plant nutrients? Do they contain too high concentration of toxic elements (such as Pb, As, Cd, ) making the food production unsuitable for human alimentation?
(2) Can we identify ancient preferential liquid water pathways?
By studying the element distribution at a soil-profile scale, we will be able to highlight the mineral element mobility through a soil profile. On Earth, mineral mobility is driven by water and wind transport, vegetation cycling, etc. As Martian environment does not present any current vegetation or life, liquid water transport seems to be the only potential driver of minerals mobility through vertical and lateral fluxes. According to their solubility, specific elements are more relevant to study because they are more susceptible to dissolve and be taken away by the liquid water. By studying the element concentration distribution along soil profiles at different locations, their variability will allows us to observe their mobility and assess the potential presence of liquid water fluxes. The aim is to imagine a transposable protocole on future Martian rovers, in order to reproduce it up there and study the potential ancient presence of liquid water…and therefore potential ancient Life!
How is working a pXRF device and what are its advantages ?
The portable X-Ray Fluorescence device relies on the X-ray fluorescence principle to quantify the concentration of mineral element in a sample. It allows to detect every element from the periodic table from Magnesium up to Uranium, even to heavier elements depending on the calibration of the instrument. This device has already been used to assess element content from Wallonia soil, to more remote areas such as Siberia and Alaska (permafrost region). While laboratory standard methods can be quite expensive and time-consuming, the pXRF device offer a faster and cheaper method, and can also performs in situ measurement. Using this device on Mars would avoid to have to bring back any sample on Earth and measurement would be directly stored in onboard computers.