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### 421-GeologyReport

 Geologist's Report Date: April 21, 2015 Crew Geologist's Name: Auriane Canesse Hello Earth, Here is a summary of everything that has been done for our geology experiment. I will begin by reminding briefly the goal of our study and I will then describe the results we obtained. \\introduction The initial goal of our experiment was to map the magnetic susceptibility of the ground in order to study its variation. The susceptibility varies with the composition of the soil: it is quite low for sand but very high for iron for example. But since our instrument also measures electric conductivity, we decided to measure this second property too. \\ field sessions We began by mapping the magnetic susceptibility of the ground around the station then went to further places to take more measurements. On April the 15th we mapped the surrounding of the hab but since Gaspard's GPS didn't work we had to take positions by hand with a meter. Since it was much slower than planed we took only two small sets of measurements. For the first one we mapped an area of 25x3m behind the hab. The buried tank behind the hab appeared very well on the data. For the second set of measurements we took measurements every 3m on 140m to see if there was a global change. But we only had only insignificant variations around a constant mean. The magnetic susceptibility of the ground seems quite uniform. We will try to take new measurements at a totally new location to see if we measure different values. On April the 16th as we went to a dry river bed to take hydraulic measurements we also took magnetic susceptibility measurements in the river bed and on the banks but the results appeared to be similar to the previous ones. On the April 17th we took measurements on several hills close to the station. Again, there was no significant changes of the magnetic susceptibility. On the April 18th we went to another river bed, the instrument was showing biased results for the magnetic susceptibility because of the heat. So we measured the electric conductivity of several river's sections instead. We found interesting variations: it had rained on the previous day and the conductivity appeared to be much higher in the bottom of the river than on the banks (so its humidity was higher). The two banks also had different mean conductivity values which could explain the presence of plants on the right bank only (the wetter one). On the April 19th we went on the cliff West of the station to measure susceptibility and conductivity. They both appeared to be approximatively constant and not very different from the values obtained in the plain. On April the 21st, since the weather had been dry for 4 days we went back to the second river to take more conductivity measurements in order to compare them with the previous ones. We had expected the soil to be dry but surprisingly it was still wet only 2cm below the clay crust. The measurements we obtained were quite similar to the previous ones: we measured the same river profile, which did seem coherent. \\ Results I will now sum up the results mentioned above The magnetic susceptibility turned out to be uniform: the measurements can be taken at different locations, on different geological stratum (plain, hills, cliffs), with different humidity rates (stream-beds, dry or rainy weather), the results are always similar: small variations around a nearly null mean. The measured values don't seem to be differentiable from the noise of the instrument. The talkie-walkies interferes with the instrument (which is very sensitive), therefore they should not be used while measuring. This can be a problem for automatic measuring (instrument connected to a computer) since the talkie-walkie's interference would not be differentiable from soil abnormalities. Magnetic susceptibility can be used to detect buried metallic objects, like tanks (but I don't think we will loose any of these on Mars.) The electric conductivity varies around river beds in a significant way, it shows an important difference of humidity between the banks and the bottom, even long after the last rain. The soil stays wet for quite a long time (which isn't obvious for a desert).