An international team of researchers has identified seasonal changes in bright deposits inside craters across Mars’ northern polar ice cap. The findings suggest that local climate conditions, rather than changes affecting the entire polar cap, play a major role in shaping the deposits.
The study analyzed images of 36 craters captured by the High Resolution Imaging Science Experiment camera aboard NASA’s Mars Reconnaissance Orbiter between 2006 and 2025. This interval covers Mars Years 28 through 38. Researchers examined whether ice deposits on crater floors expanded during winter and contracted during summer.
Changes in the bright deposits were detected in 32 of the 36 craters. The researchers interpret these variations as evidence that seasonal frost deposits grew and receded over time. No changes in brightness were observed in the other four craters.
The results also showed that frost behavior varied from one crater to another and from one Martian year to the next. The study attributes this spatial variation to factors such as local topography, crater geometry and microclimatic conditions, which can affect energy balance and the movement of water vapor.
Mars’ northern polar ice cap is composed of water ice, while its southern cap is made of carbon dioxide. Understanding how water ice changes seasonally in the north could help scientists investigate the planet’s longer-term climate history.
The researchers say the findings provide a basis for future modeling of localized Martian climates. Their study, “Variability of Bright Deposits in North Polar Residual Ice Cap Craters on Mars,” was published in the Journal of Geophysical Research: Planets.
Sources: Phys.org.