From: Mars Society
Posted: Tuesday, July 24, 2001
On the first EVA of Rotation 3, a Magnetic Property Experiment was set up underneath the Habitat (to protect it from rain). Below follows a description of the experiment and its relevance to studies on Mars and at the simulation site.
It is a device called the Magnet Array (MA). It consists of 5 magnets of various strength that can attract airborne dust with varying efficiency. The strongest magnet is able to attract a weakly magnetic mineral such as hematite (alpha-Fe2O3). A strongly magnetic mineral such as pure magnetite (Fe3O4) can stay on all five magnets. By imaging the dust pattern accumulated on the MA, information of the magnetic properties of the dust is provided and in consequence the magnetic mineralogy can be characterized.
The MA deployed on Devon is similar to those which, as part of the IMP camera payload, flew on Mars Pathfinder (NASA 1996). On Mars the dust was attracted to the four strongest magnets and possibly to the weakest one. This showed that the Martian soil contains a strongly magnetic phase. Based on the dust pattern and optical spectroscopy, the phase was interpreted to be maghemite (gamma-Fe2O3).
The magnetism of the Martian soil is surprising. Soils on Earth are rarely as magnetic as the Martian soil appears to be. Moreover, maghemite is rarely found on Earth and its formation is not trivial. One possible way is by slow oxidation of Fe2+ to Fe3+ in water followed by precipitation.
We would like to find out how the Martian soil formed, because this will tell us about Mars in the past. The magnetic mineralogy indicates whether or not the soil formed under the presence of water, because iron reacts strongly with water (just think of rust). Therefore on the 2003 lander missions (NASA and ESA) the soil will be studied further with Mossbauer spectroscopy and other magnetic properties experiments.
Why is interesting to set up the Magnetic Array on Devon Island?
The Haughton Crater and its surroundings resemble the Martian landscape and therefore, it is an excellent site for simulating operations on Mars. By comparing the results of the magnetic experiment on Devon Island with those from Mars we can find out if the airborne dust on Devon actually has similar magnetic properties to those of the Martian dust and thereby how good an analog the soil of Devon is to that of Mars.
In the end of Rotation 3, the MA will be photographed by a camera similar to the PanCam from Pathfinder, and the dust pattern will be compared to that obtained on Mars.
These images courtesey NASA JPL, Peter Smith's Imager for Mars Pathfinder, University of Arizona, and to the Niels Bohr Institute.
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