Tracking Mean Solar Time and Dates on the Moon – Reprising Kenneth Franklin’s Lunar Time System
£0.00
Michael Allison
2025.78.0034
DOI: https://doi.org/10.59332/jbis-078-02-0034
The European Space Agency and the U.S. Office of Science and Technology Policy have announced a need for a standardized “Coordinated Lunar Time” for robotic and human activities on the Moon. Much of the ensuing discussion has focused on the problem of aligning high precision clocks on the Moon with Coordinated Universal Time (UTC), including the relativistic effect of a ~58 μs/day divergence between the terrestrial and lunar frames, as important to orbital navigation systems in cislunar space. A separate but so far unresolved issue is the definition of a natural lunar time-keeping system for some human-adapted measure of the Moon’s solar illumination and extreme excursions of surface temperature in step with the 29.53059- day synodic period. Here is reprised a nearly forgotten 1970 proposal by the astronomer Kenneth L. Franklin. His Lunar Time (LT) system combined E.W. Brown’s lunation numbering of repeated lunar phases with a regular division of the synodic period into 30 “lunes” each of 0.9843529 terrestrial days, further sub-divided into 24 “lunours,” with decimal sub-units replacing sexagesimal minutes and seconds. Explicit expressions are given for conversion between UTC and LT, also the subsolar co-longitude and latitude, as important to the seasonal variation in the polar regions.
Keywords: Space Timing Systems, Lunar Settlement, Space History, Space Medicine
