Planetary Science and the Human Calendar for Mars

Professional astronomers and planetary scientists have proposed systems for organizing time on Mars for more than 130 years. Beginning with Percival Lowell and colleagues at the Lowell Observatory in the 1890s and continuing through contributions from observers at Lick, Mount Wilson–Palomar, Fels, and Collurania observatories, as well as later work at NASA centers and other research institutions, the idea of a human-scale Martian calendar has repeatedly arisen from within the scientific community. Designs have varied in the number and length of months, intercalation methods, and choice of epoch, yet none has achieved consensus. The community has instead standardized on a minimal physics-based framework of continuous sol counts, solar longitude (), and Mars Year numbering. This framework optimally serves research and robotic operations but leaves unresolved the question of a civic calendar suited to human social organization. The prolonged silence on the latter issue stems from the sufficiency of existing metrics for current needs, institutional caution against speculative projection, and short-term research horizons. Nevertheless, a widely recognized Martian calendar would enhance public familiarity with the planet and thereby support the sustained political and financial backing on which planetary science depends. The present paper reviews the historical record of scientific proposals, examines the reasons for non-engagement, and argues that eventual community consensus on the regular use of one human-oriented system—without endorsing any particular design—would serve the long-term interests of the field.