Breccia and basalt classification of thin sections of Apollo rocks with deep learning

TL;DR

A framework for classifying rock types in thin sections of lunar rocks is introduced, leveraging the vast collection of petrographic thin-section images from the Apollo missions, captured under plane-polarized light (PPL), cross-polarised light (XPL), and reflected light at varying magnifications.

Abstract

Human exploration of the moon is expected to resume in the next decade, following the last such activities in the Apollo programme time. One of the major objectives of returning to the Moon is to continue retrieving geological samples, with a focus on collecting high-quality specimens to maximize scientific return. Tools that assist astronauts in making informed decisions about sample collection activities can maximize the scientific value of future lunar missions. A lunar rock classifier is a tool that can potentially provide the necessary information for astronauts to analyze lunar rock samples, allowing them to augment in-situ value identification of samples. Towards demonstrating the value of such a tool, in this paper, we introduce a framework for classifying rock types in thin sections of lunar rocks. We leverage the vast collection of petrographic thin-section images from the Apollo missions, captured under plane-polarized light (PPL), cross-polarised light (XPL), and reflected light at varying magnifications. Advanced machine learning methods, including contrastive learning, are applied to analyze these images and extract meaningful features. The contrastive learning approach fine-tunes a pre-trained Inception-Resnet-v2 network with the SimCLR loss function. The fine-tuned Inception-Resnet-v2 network can then extract essential features effectively from the thin-section images of Apollo rocks. A simple binary classifier is trained using transfer learning from the fine-tuned Inception-ResNet-v2 to 98.44\% ($\pm$1.47) accuracy in separating breccias from basalts.

Figures (8)

• Figure 1: In 1965, the United States Geological Survey (USGS) developed a prototype for a semi-automatic machine to cut and prepare thin sections of rocks cary1965. This innovative device was specifically designed for the Apollo Applications Program and Advanced Lunar Programs Groups, aiming to streamline the analysis of lunar samples.
• Figure 2: Example of a thin section under different polarized light conditions: Reflected light, plane-polarized light, and cross-polarised light.
• Figure 3: Example of augmentations of an image of a thin section of lunar rock.
• Figure 4: Customised Inception-ResNet-v2 adapted from Szegedy2016. 5 of the layers are frozen during network training and un-freezed during network fine-tuning.
• Figure 5: A simple framework for contrastive learning of visual representations from Chen2020.