Construction of the image database of Earth's lava caves useful in identifying the lunar caves

Cave on the Moon is considered as the most appropriate place for human to live during the frontier lunar exploration. While the lava flows, the outer crust gets cooled and solidified. Then, the empty space is remained inside after lava flow stops. Such empty space is called the lava caves. Those lava tubes on the Earth are formed mostly by volcanic activity. However, the lava tubes on satellite like Moon and planet like Mars without volcanic activity are mostly formed by the lava flow inside of the crater made by large meteorite impact. Some part of lava tube with collapsed ceiling appears as the entrance of the cave. Such area looks like a deep crater so called a pit crater. Four large pit craters with diameter of > 60 m and depth of > 40 m are found without difficulty from Kaguya and LRO mission image archives. However, those are too deep to use as easily accessible human frontier base. Therefore, now we are going to identify some smaller lunar caves with accessible entrances using LRO camera images of 0.5 m/pixel resolution. Earth's lava caves and their entrances are well photographed by surface and aerial camera in immense volume. Thus, if the image data are sorted and archived well, those images can be used in comparison with the less distinct lunar cave and entrance images due to its smaller size. Then, we can identify the regions on the Moon where there exist caves with accessible entrances. The database will be also useful in modeling geomorphology for lunar and Martian caves for future artificial intelligence investigation of the caves in any size.