Scientific equipment of the “Mars-Express” orbiter allowed detailed studies of water cycle on the Red planet.

Research was performed by means of various devices, among which there were PFS (planetary Fourier spectrometer), SPICAM (general spectrometer) and OMEGA (mapping spectrometer). Russian scientists contributed a lot to development of mentioned equipment.

Martian atmosphere showed traces of water vapour, though it is much dryer than earth’s atmosphere. If we try and condense all water of Martian air, it will cover Mars with a thin 10-micron-thick film. Compare with Earth – 2-cm-thick water film would have covered our planet after condensation. However, small amounts don’t prevent Martian water from continuous turnover of evaporation and condensation, which can be observed on Earth. Condensed water precipitates on Mars’s surface, where evaporates and returns to atmosphere. There water moves with the wind, until the time to “rain” comes. This permanent water turnover has a great effect on Martian climate.

 

 

Scientists from Ames research Centre of NASA say that Martian water turnover is much less intensive than that of the Earth. Nevertheless, water vapour content in Mars’s atmosphere varies significantly, depending on time of the season and geographic location.

Russian scientists also comment the situation. They say that water ice on Mars is located in the polar caps and inside soil. In order to move form one place to another, ice should first melt and then evaporate to get into atmosphere. As soon as water vapour arrives to the atmosphere, it condenses and forms clouds, which reflect solar radiation. Thus, clouds have cooling effect on Martian climate, claim researchers from the Institute of Space Research.

Researchers compared data from “Mars Express” with data from NASA’s “Vikings”, which explored the Red planet in the seventies, and suggested that water vapour content on Mars changed significantly from year to year. If we consider “Vikings” measurements to be true, then almost 40 years ago there was twice as much water in Mars’s atmosphere over the North Pole, as it is now. However, Russian scientists think that after proceeding of “Vikings” results with modern methods, they would become closer to “Mars Express”. This means that Martian water turnover is more stable than scientists consider it to be.

 

 

Researchers believe that main water supply on Mars is its northern polar cap. When summer comes, dry ice (frozen carbon dioxide) evaporates from poles, revealing water ice layer, which also vapours up to the atmosphere. In the south dry ice never totally disappears, keeping water ice trapped. Existing computer models show that evaporation and condensation of water ice on the Martian North Pole is the key process of the water cycle on the Red planet.

French planetologists previously thought that all dry ice should disappear from the northern polar cap before water ice layer opened, thus allowing water to enter atmosphere only in late spring. However, evaporation of seasonal deposits of carbonic ice also releases some water ice, forming a “ring” around the pole and promoting water to enter Martian atmosphere in early spring.

Stable water ice is never found in latitudes, lower than 45° from the equator. Latitudes, higher than 50° towards both poles, allow ice to exist under the surface on the permanent basis. Recently scientists mapped ice distribution around poles at mentioned latitudes. When latitude exceeds 85°, water ice appears on the surface. In some places ice thickness reaches 2-3 km. South Pole looks almost the same, but covered with frozen carbon dioxide.

OMEGA device shows minerals, which absorbed water: water molecules are “stuck” to various minerals in upper layers of Martian soils. These minerals can also emit water vapour in summer, after heating. Scientists are sure that Martian climate and water cycle require thorough and long-term research.

Source: Science & Life

Kizilova Anna