Mars Water

predicted atmospheric water abundance links to gif image

Water is the key to the most important scientific questions dealing with Mars.

line plot predicting water vapor abundance vs. 
time Based on spacecraft and Earth-based observations of Mars, we have a good understanding of the annual cycle of water vapor in the Martian atmosphere. The most important source of this water is the north residual polar cap from which large quantities of water vapor sublime during late spring and early summer. The apparent regularity of the cycle allows us to make a model prediction of today's atmospheric water vapor distribution on Mars. Note that the total amount of water in the atmosphere is very small (measured in precipitable micrometers). If all the water in the Martian atmosphere were to rain out at any given time, it would make a puddle less than a hundredth of a centimeter deep!

line plot predicting total exchangeable water 
abundance vs. time Detailed computer modeling allows us to infer that there is another significant reachable reservoir of water on Mars, besides the polar caps and the atmosphere. Approximately 10 times the total atmospheric inventory of water can be found adsorbed in the top few centimeters of the Martian soil. This could represent an important resource and will be the object of future landed spacecraft missions. Indications are that this adsorbed water supplies much of the atmospheric water vapor that exchanges between the hemispheres during the course of the Martian year.

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Curator: Howard Houben
Responsible NASA Official: Jeffery Hollingsworth

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