Specialists invented how to “pull out” the data on the exact composition of Martian rocks from the readings of the device, which was not intended for these purposes. The achievement is described in a scientific article published in the journal American Mineralogist by a group led by Shaunna Morrison of the University of Arizona.
Recall that “Curiosity” has on board a device called CheMin, which is an abbreviation for the phrase Chemistry and Mineralogy Instrument (“chemical and mineralogical tool”). He can distinguish between minerals, for example, identify feldspar or olivine. However, the device does not have the ability to determine the exact chemical composition of the samples.
We will explain that the chemical composition of one and the same mineral can differ (including due to the impurities of “foreign” atoms). At the same time, information about its exact formula allows us to restore the conditions in which the mineral was formed. For example, to answer the question whether this happened in contact with water.
Morrison found a way to extract this information from CheMin’s data. As is known, the atoms in the crystal are arranged in an orderly fashion and form the so-called crystal lattice. It consists of repeating identical “bricks”, which are called elementary cells. The size of such a cell depends on the composition of the mineral. A CheMin device can determine its length using X-ray diffraction.
“I looked at the literature, collected and analyzed thousands of measurements of both the mineral composition and the size of the unit cells, and then determined the mathematical relationship between them,” explains Morrison in a press release. “Once this relationship was established, it could be used for more detailed study of minerals in Martian samples with the help of “Chemin”.
Morrison, along with colleagues, analyzed data on 13 samples collected by “Curiosity” in the Gale crater. In particular, scientists have determined the exact composition of feldspar collected in different places, and the percentage of magnesium in olivine. Comparing this information with the results of a study of Martian meteorites, the authors hope to clarify the role of water in the formation of the last mineral. But the main achievement is the method itself, with the help of which it will be possible to subject to additional analysis all soil samples that have already been collected or will still be collected by the rover.
“Thanks to Shonny’s creative approach, we’ve improved Chemin’s resolution by an order of magnitude,” concludes the work of Robert Hazen of the Carnegie Institution. “The result is the brightest picture of the mineralogy of another planet.”
Let us explain that under the resolving power the scientist here understands the detail of the information obtained.