Page 2 2. These scenarios include unmanned sample return, unmanned scientific, and manned exploration missions. This is important because a slight change in humidity has a large effect on the amount of atmosphere that needs to be processed for a given mass flow of water. To maximize water production, the landing site must be chosen with care. Lower altitudes will have higher pressures and thereby higher humidities.
Northern latitudes are more humid due to proximity of the polar cap.
Subsequently, southern latitudes are generally dryer than northern. The lower latitudes of the northern hemisphere are desirable from the standpoint of higher solar flux for photovoltaic cells. Even if the planetary maximum of humidity is assumed, there is still not enough to allow passive adsorption without a very large bed. This is equivalent to about 1.1 cubic meters per second for one kilogram of water every Martian day. Therefore, a forced air adsorption device must be considered.