lunar lava tubes
... that lunar lava tubes could provide natural shelters for manned lunar habitats?
... that <b id="mwFao"><a href="./Lunar_lava_tube" id="mwFas" rel="mw:WikiLink" title="Lunar lava tube">lunar lava tubes</a></b> could provide natural shelters for <a href="./Colonization_of_the_Moon" id="mwFaw" rel="mw:WikiLink" title="Colonization of the Moon">manned lunar habitats</a>?