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Mineralogy of the Meridiani Planum site based on the MIniTES spectra of the Opportunity rover and the PFS Mars Express spectrometer

Presentation #217.05 in the session Mars’ and Martian Moons’ Surface Properties and Composition (Oral Presentation)

Published onOct 23, 2023
Mineralogy of the Meridiani Planum site based on the MIniTES spectra of the Opportunity rover and the PFS Mars Express spectrometer

The Opportunity rover explored the area of Meridiani Planum. In total, it has traveled a distance of 45.16 km, along which it performed spectrum measurements with the MiniTES spectrometer, in the mid-infrared range. The rover’s route included several craters: (e.g. Endurance, Erebus, Victoria, Endeavour). It is possible that these were areas where there was water in the geological past.

In many publications one can read that, on the basis of the Mossbauer spectrometer apparatus, large amounts of iron oxides and sulphates were discovered. We want to check whether the data from MiniTES are consistent with the data obtained from Mossbauer. We also want to compare data from Mars Express’s PFS. Note that the trajectories of the rover and the satellite were roughly along the meridians.

For the interpretation of Opportunity rover spectra, we used data from sols: 72, 210, 910, 911. We selected only the best spectra. From the PFS, we selected orbits that passed through the path of the Opportunity rover. These were orbits 529 and 3198, which had noise-free spectra.

Spectra from sol 72 (near Eagle Crater) have distinct bands of hematite. We compare them with a mixture of Deccan basalt 34% and hematite 33% made by linear addition of the spectra [Fig.1]. The addition of jarosite or gypsum sulphates does not give the proper spectrum shape.

The spectra from sols 910 and 911 (near Victoria Crater) are identical and show much less hematite content on the surface of Meridiani Planum. On the other hand, one can see a high dust content in them, where the mild minimum is in the range of 900-1200 cm-1 with the main lowest band minimum of 1075 cm-1. The spectra from these sols best match the spectra of the terrestrial tholeiitic basalt from Iceland. However, in the averaged spectra from sol 210 (near Endurance Crater) we do not notice any bands of hematite.

For comparison, the spectra from the two orbits of PFS 529 and 3198 passing through the path of the Opportunity rover do not have hematite bands, although the TES spectrometer (MGS) has found large amounts of them. However, dust bands with a minimum of 1075 cm-1 are clearly visible. Only the spectrum from the 3198 orbit has a slight minimum around 325 cm-1, but with such a small band it is difficult to tell whether it comes from hematite [Fig.2].

The occurrence of hematite is evidence of the existence of water in this area in the past of the planet. It contains crystals of hematite. On Earth, this mineral is formed near thermal springs or at the bottom of stagnant water reservoirs.

Bolewski, A. (1982); Bolewski, A. (1990); Christensen P., et al., (2000); Klingelhofer, G., et al., (2004); Zalewska, N., et al., (2019);

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