Magnetic Properties Experiments on the Mars Pathfinder Lander: Preliminary Results

Many of the particles currently suspended in the martian atmosphere are magnetic, with an average saturation magnetization of about 4 A·m 2 /kg (amperes times square meters per kilogram). The particles appear to consist of claylike aggregates stained or cemented with ferric oxide (Fe 2 O 3 ); at least some of the stain and cement is probably maghemite (γ-Fe 2 O 3 ). The presence of the γ phase would imply that Fe 2+ ions leached from the bedrock, passing through a state as free Fe 2+ ions dissolved in liquid water. These particles could be a freeze-dried precipitate from ground water poured out on the surface. An alternative is that the magnetic particles are titanomagnetite occurring in palagonite and inherited directly from a basaltic precursor.