The water cycle on Mars is not completely understood but it might be similar to the situation shown below.
The soil on Mars has been studied extensively and measurements indicate that certain salts known as perchlorate might be present in the soil on Mars and this is highly interesting. The reason why the scientific community is suddenly extremely interested in salts (that are considered contamination if found on Earth) is because of their ability to extract water vapour from the air. Professor F. Javier Martín-Torres et.al. published an article in 2015 showing results from NASA’s Curiosity rover regarding water activity.
The graph shows the seasonal behaviour of the relative humidity on Mars over one full Martian year. As seen the relative humidity is maximized at beginning of winter. Professor Martín-Torres at Luleå University of Technology was also able to show that there might even be a daily water cycle on Mars from the graph seen below.
If this is correct that would mean that there might be a potential water reserve on Mars in the form of brines and this is very interesting. Not only would it completely change our understanding about the Martian environment. It would also potentially be of importance during manned missions to Mars. Prof. Martín-Torres is the PI of the instrument called HABIT (HabitAbility, Brine, Irradiance and Temperature) recently selected by ESA to be part of the European contribution to the ESA/Roscomos Suface Platform ExoMars 2018 that will investigate brines on Mars and that is the foundation of the SALACIA project. An example of how brines attract water vapour from Earth’s atmosphere can be seen in the pictures below.
It can also be noted that a recent NASA announcement by Lujendra Ojha, et. al. (2015), describing recurring slope lineae, sees perchlorate salts as a likely cause for the observed signal of hydrated salts.
SALACIA is short for Saline Liquids and Conductivity in the Atmosphere and can be seen as a pre-study for the mission proposed by Professor Martín-Torres. The SALACIA mission intends to place vessels with the salts present on Mars and examine their characteristics during launch and how good they are at absorbing water at low pressure environments.
Specifically, our goals are the following:
- Technological: demonstrate that SALACIA will work under launch conditions. Study the behavior of the salt during flight and identify mission-critical weaknesses for future missions to Mars.
- Scientific: characterize the ambient conditions (air temperature, relative humidity) throughout the troposphere, stratosphere and mesosphere. Measure the speed with which the salts can obtain water from the atmosphere. Measure the obtainable amount of water.
SALACIA needs a rocket to achieve realistic flight conditions, real-world atmospheric conditions (pressure, composition and humidity), and rapid pressure and temperature changes. The simultaneous combination of all of these characteristics can only be achieved in a meaningful way through the use of a rocket. Since the ultimate goal of our university is to send the HABIT instrument to Mars, the knowledge gained by SALACIA could prove to be invaluable.
SALACIA will measure the following data:
- Brine conductivity in each vessel
- Air temperature outside the vessels
- Temperature in each vessel
- Visual observation of the salt behavior using a camera system
Our instrument is scheduled to fly on the Rexus rocket in 2017. We plan to expose typical salts found on Mars to a rocket launch and observe how their characteristics change. With this information the HABIT instrument might be designed in an optimal way in order to guarantee useful results. From idea to manufacturing: pictures below shows how, with time, the experiment goes from our design on the Computer-Aided Design program to onhands mechanical structures in our lab.
The salts that we are using are: magnesium perchlorate, sodium perchlorate, calcium perchlorate and calcium chloride. In order to prevent the salts from leaving the vessels, while still being able to expose it to the atmosphere a special type of filter will be used. How this filter will behave during the flight is one of the interesting things to observe during the experiment. 3D-printed structures of the mechanical design were made to insure that everything fits and to see if there was anything that was needed to change before sending the drawings away on manufacturing.
Inside the vessels we will also place conductivity measuring equipment which will allow us to determine how much water has been absorbed by the salts. This will be possible as conductivity will increase with increased water presence in the salts. These measurements will also provide good information about how one might expect the salts to operate at low pressure environments.
Manufactured mechanical parts:
Assemble stage (current stage) of experiment: