The circumnavigation of the moon

The unsupported circumnavigation of the lunar surface, either around the equator or over both poles is the longest distance expedition that can be implemented on the lunar surface. This mini-review describes some of the attributes of this expedition and reviews some of the dangers that the team will face. By travelling at just under 16 km/hr along the western terminator around the equator the 29 day, 11,000 km, expedition can avoid darkness altogether and have 14 days of light to repair a vehicle should it break down. The minimum mean speed possible to avoid dark will be just over 10 km/hr. Periods of complete darkness, which will be encountered during the crossing of one of the poles during a polar circumnavigation (on account of the moon's small obliquity) or long-term breakdown during an equatorial circumnavigation, will impose challenges in navigation and vehicle manoeuvring not dissimilar to overwintering operations at the terrestrial poles. Pressurized lunar ball tents are described, together with some other field innovations for studies away from pressurized vehicles. The accomplishment of the first lunar circumnavigation will represent a significant milestone in Solar System expeditionary endeavour. Other lunar expeditions are listed.