This data set consist of daily mass densities derived from precise orbit determination of the Mars Reconnaissance Orbiter (MRO) satellite at 251 km and the Mars Odyssey (MO) satellite at 412 km. The data encompass 2006-2020 (MRO) and 2002-2020 (MO). Both satellites are in low-eccentricity near-polar day/night Sun-synchronous orbits. Also included are auxiliary data sets consisting of daily 10.7 cm solar radio fluxes adjusted to Mars orbit, and daily values of column dust optical depth from TES and THEMIS nadir observations integrated over all longitudes and between 0º and 90ºS latitude More details are found in the README.txt file. This data set is made available in connection with the following publication: Forbes, J.M., Bruinsma, S.L., Zhang, X., Marty, J.-C., Laurens, S. (2024). Long-term Variability of Mars’ Exosphere Density Based on Precise Orbital Analysis of Mars Reconnaissance Orbiter and Mars Odyssey. Geophysical Research Letters, 51. https://doi.org/10.1029/2023GL107044