Free Astronomy Magazine May-June 2018

11 MAY-JUNE 2018 PLANETOLOGY on the contrary, they are mostly filled with solidified lava residue. Considering just the sizes of the skylights mentioned above, it is already clear that lunar and martian lava tubes are undoubtedly suitable for accommo- dating permanent hu- man bases of consid- erable size while also providing easy access to the surface through the skylights. Since these structures have remained unal- tered for likely millions of years, it’s equally likely they are solid and stable enough to remain unchanged for a very long time. Therefore, they do not only represent an ex- cellent solution to ex- ternal threats (within certain limits), but they may also offer the opportunity to create large airtight environ- ments filled with breath- able air. It is important to notice that any under- ground bases installed in those subterranean cavi- ties would also be natu- rally protected from thermal variations be- tween day and night, which are very severe on the Moon and less ex- treme on Mars. The in- terest of researchers in the lava tubes has in- creased significantly in recent years. They are al- ready planning an or- biter that is specialized for the discovery and measurement of those structures through so- phisticated radar tech- niques − the LAROSS mission (Lunar Advanced Radar Orbiter for Subsurface Sounding). Specific training programs for astronauts are already being implemented, such as PAN- GAEA (Planetary Analogical Geological and T HEMIS image of probable cave entrances on Arsia Mons. The pits have been informally named (A) Dena, (B) Chloe, (C) Wendy, (D) Annie, (E) Abby (left) and Nikki, and (F) Jeanne. [NASA]