MoonIndex: A Tool to Democratise Prospecting for Minerals on the Moon
Javier Eduardo Suárez Valencia of the University of Padova (Italy) reports how Europlanet’s development of an open-source tool to study the mineralogy of the Moon has led to the discovery of new lunar features.
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Analysing the composition of the lunar surface, using multispectral or hyperspectral data, is an important step towards understanding the Moon’s formation and identifying the most interesting locations to explore. The Moon Mineralogy Mapper (M3) carried by India’s Chandrayaan-1 mission, which provided the best resolution spectral datasets of the lunar surface, is currently the most widely used source of data for this purpose. The M3 data can be used to create spectral indexes – powerful tools to understand the geological processes that shaped the Moon, and valuable input for mapping. These products are computed by combining singleband or composite images, or performing mathematical operations on data in certain wavelength bands, and highlight intrinsic spectral signatures that indicate the presence of specific elements and minerals.
Until recently, the correction of M3 data and the creation of spectral indexes could only be done using expensive proprietary software, limiting access within the scientific community to those with the available financial resources. However, with support from two European Commission (EC) funded programmes, the EXPLORE project and the Europlanet 2024 Research Infrastructure (RI) activity, Geological Mapping (GMAP), we set about developing a free and open-source package called MoonIndex to process lunar data, with the aim of creating a tool that could be modified and improved by the community over time.
Creating MoonIndex
MoonIndex is an open-source Python package that recreates thirty-eight spectral indexes using datasets from M3 and published studies of the mineralogy of the lunar surface. Given the versatility of spectral indexes, MoonIndex can be used to estimate the presence of several minerals like pyroxene, spinel, anorthosite and olivine, as well as to differentiate between geological units like impact ejecta or volcanic domes.
We tested the tool and compared the results with the literature for three well-studied locations on the Moon: the Apollo Basin, the Aristarchus Crater, and Vallis Alpes.1 The results demonstrated MoonIndex’s potential as a reliable tool for the compositional analysis of the lunar surface, achieving high levels of fidelity with previous studies and even improving the data in some circumstances.
Deploying MoonIndex
In our first major study using MoonIndex, we carried out a detailed geological analysis of the Valentine Domes.2 This system of intrusive domes is an interesting location for lunar exploration, as it is a very good example of a geological process that is poorly understood in other planetary surfaces, and could give us interesting information about lunar magmatism and the evolution of the crust.
The Valentine Domes were created by magmas that crystallised below the surface and were later pushed upwards by faults and erosion. Part of the reason intrusive domes are not very well understood is because they are difficult to detect. The structures are usually small hills with low slopes, and they do not greatly change the composition of the locations into which they intrude, so it is difficult to search for them in remote sensing datasets.
In our study, we used MoonIndex and recent high-resolution datasets to produce a geostratigraphic map of the Valentine Domes. This mapping technique combines morphological and compositional data, resulting in an integral map that contains information about the genesis of the structures in an area and the minerals they contain.
One of our initial and important results was the discovery of a new dome, which we found using an aspect map that shows the direction of slopes and highlights small changes in the topography. The aspect map clearly revealed the dome structure, and we believe it is a valuable tool for these studies that could lead to the discovery of many more intrusive domes.
Our detailed study of the Valentine Domes also revealed the presence of secondary domes – smaller, younger and compositionally different domes on top of the main structures. The secondary domes are aligned with each other, generating groups that likely follow a structural pattern of buried dykes. Other structures like channels and volcanic vents are common in the location, suggesting that the igneous system below was bigger and stronger than previously thought. These structures record the history of an intrusive system that was active for several million years, after about 2.98 billion years ago and until at least 1.88 billion years ago.
Conclusion
The study of the Valentine Domes has not only demonstrated the power of the MoonIndex tool, but has revealed an intriguing system on the Moon that is an attractive target for future exploration. By developing open source tools like MoonIndex, and creating high-level scientific products from them, Europlanet can support the democratisation of science and help to strengthen planetary community.
Europlanet 2024 RI and EXPLORE have received funding from the European Union under Grant Nos. 871149 & 101004214.
