Olympus Mons is the solar system鈥檚 sickest half-pipe. It and other Martian volcanoes act like skate ramps to launch dust up to 75 kilometres above the planet鈥檚 surface, observations from NASA鈥檚 Mars Reconnaissance Orbiter (MRO) have revealed.
Massive dust storms can whip particles up into the Martian atmosphere and turn the entire planet hazy. But there are other dust layers that don鈥檛 seem to be related to large storms, say of Hampton University, Virginia and his colleagues.
The team analysed data from dust sensors on MRO and discovered unusually thick layers above an altitude of 50 kilometres extending horizontally for over 1000 kilometres. They seemed to cluster around Olympus Mons and the Tharsis Montes, a group of three large volcanoes nearby.
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There were no signs of these layers elsewhere on Mars, suggesting that the volcanoes play a role in their formation.
The layers were also most common during Mars鈥檚 northern summer, when the volcanoes鈥� summits are heated more intensely than their slopes, creating thermal currents.
Modelling suggests that localised storms with winds of over 150 kilometres per hour could be blowing dust up the slopes, forming layers up to 50 kilometres above Olympus Mons鈥檚 25-kilometre peak.
鈥淥ur interpretation is that the dust layers do come from volcanically based dust storms, which occur far more frequently than previously inferred from observations,鈥� says Heavens.
It鈥檚 unlikely that these dust layers are related to the mysterious high-altitude Martian cloud reported by astronomers earlier this year, says Heavens, as they are seen above a completely different part of Mars. They could be partly responsible for the planet鈥檚 drying out, however.
鈥淭hese dust storms may mix water vapour as high as they do dust, so they may be a part of the water vapour escape process,鈥� he says.
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