It has been well established that there was once liquid water on Mars. Now the only water on the planet is contained in polar ice or water vapor in the atmosphere. Scientists have now mapped the distribution of water vapor, revealing more about the Red Planet’s atmosphere.

Russian scientists, along with their French and American colleagues, created the map using ten years worth of data collected by the Russian-French SPICAM (Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars) spectrometer. Ten years is the longest period of observation of Mars’ atmosphere, revealing the existence of seasonal variations in the atmosphere’s water concentration.

The new data allowed for a more complete picture of the water cycle in Mars’ atmosphere. The content of the water vapor in the atmosphere reaches a maximum level of 60-70 microns of water released during the summer in the northern regions. The southern regions released significantly less water during the summer, with levels on reaching a maximum of 20 microns.

The scientists also noted a significant reduction of water during global sandstorms, believed to be caused by absorption and condensation on the planet’s surface.

“This research, based on one of the longest periods of monitoring of the Martian climate, has made an important contribution to the understanding of the Martian hydrological cycle — the most important of the climate mechanisms which could potentially support the existence of biological activity on the planet,” said Alexander Rodin, co-author of the study, in a statement.

Studying the water content of Mars could prove beneficial for future expeditions to the planet. The conditions on Mars do not support standing water on the surface. Low temperatures combined with low atmospheric pressure eliminates the possibility of finding reservoirs of water. Rather, on Mars there exists a layer of permafrost, with significant reserves of frozen water concentrated at the poles.

The Moscow Institute of Physics and Technology State University point out that the water content in Mars’ atmosphere is significantly less than Earth’s. If the entirety of the water vapor in the Martian atmosphere were to be spread over the surface, at most it would only be 20 microns deep. If you were to do the same on Earth, the result would be thousands of times greater.

Observation of the Martian atmosphere has been an ongoing project since the late 1970s. The first SPICAM iteration was built for the Russian Martian orbiter Mars 96, however the spectrometer was lost when the rocket carrying the spacecraft experienced a malfunction.

The study was originally published in the journal Icarus.