Magnetic minerals on Mars – Københavns Universitet

Mars > Research > Magnetic minerals

Approximate true colour image of magnetic dust collected on the capture magnet (right) and filter magnet (left) on the Opportunity rover. Click for larger version. Image credit: NASA/JPL/Cornell/NBI-UCPH.

Magnetic minerals on Mars

Our research is focused on the investigation of the composition of the dust, soil and rocks on Mars, as this composition can tell us a lot about the evolution of Mars. The main goal is to understand the history of water on Mars, because water is believed to be a necessary condition for life to develop and exist.

Minerals reveal the history of water

Because some minerals form in water and humid environments and others in dry environments, the mineral composition of the dust and soil contains information of the history of Martian water. Mineral formation is also dependent on the acidity of the environment which again is an important parameter for the conditions of life.

Iron oxides

Mars is in abundance of iron oxides, a group of minerals containing iron and oxygen. Some iron oxides contain other elements as well. Because of the iron, most iron oxides can be captured on permanent magnets, and the iron makes it possible to identify the minerals by Mössbauer spectroscopy.

Our magnetic properties experiments

In our experiments we generally use permanent magnets on board Mars landers and rovers to capture dust from the Martian atmosphere or from the ground. We then investigate the captured dust by optical, x-ray and Mössbauer-spectroscopy, optical microscopy and even atomic force microscopy.

Main results of the experiments

Among the most important results of our magnetic properties experiments have been the following:

  • All, or nearly all, the dust in the Martian atmosphere is magnetic, which means it can be captured on permanent magnets.
  • The magnetic properties of the dust are caused by the mineral magnetite or possibly titanomagnetite.
  • The minerals olivine and pyroxene are present in the dust.
  • The mineral hematite is present in the dust.

Magnetite, titanomagnetite, olivine and pyroxene are all generally formed in dry environments, while hematite is generally formed in water. See Formation for more details.

These findings mean that the dust particles as they are now, cannot have formed in liquid water and could not have been exposed to liquid water through long periods of time, because olivine would then have been altered.
On the other hand, the presence of hematite suggests that liquid water has taken part in the formation of at least part of the dust.

We have suggested a possible evolutionary scenario of Mars to fit these observations.