It is therefore no surprise that NASA’s Mars Curiosity rover, far away in the Gale crater, sometimes loses its electronic eyes on Martian weather events – and now, it looked like a dust devil spinning on the rocky crater floor goes.
Watching weather events on Mars, which we also see on Earth, is not only interesting, though – it can tell us a lot about seasonal atmospheric changes on the red planet.
It is approaching the Martian summer in the southern hemisphere of the planet, where the Gayle crater can be found, and the atmosphere is warming in the region. Just as uneven warming of the air on the Earth produces atmospheric motion, similarly the Martian atmosphere is also affected.
“Strong surface heat creates strong convection and sensory vortices, with strong winds around the low-pressure core,” writes Clair Newman, atmospheric scientist at Aolis Research on the Mars Exploration blog.
“If those murals are strong enough, they can pick up dust from the surface and appear as ‘devils of dust’, which we can see with our cameras.”
Dust devils are very well understood, and they come in the same way on both Earth and Mars. They form best in relatively flat, dry terrain, when the air at the surface level is warmer than the air above it.
This warm surface air rises through cooler, denser air, creating an updraft. This causes the cooler air to sink. If a horizontal wind moves, then through this vertical circulation, a dust devil gets into action.
They are extremely common on Mars, but we only know this because when they cross the ground, they sweep dust in their path, leaving them near them. In fact it is quite rare to see them in action on the red planet, as our observational abilities are limited, and the dust devils themselves are relatively short lived.
The dust devil above, seen in the top center of the image, was captured on Sol 2847 by Navcam of Curiosity, and covers a period of about 5 minutes, Newman says. Even though it sounds ghostly, the fact that we can see it means it was very powerful.
“We often have to process these images, what is changing between them, before the devils of dust are clearly visible,” she writes. “But this dust devil was so impressive that – if you look closely! – you can only see it moving to the right, at the boundary between the darker and the lighter slope, even in raw images. ”
Studying these films can reveal a lot about dust devils on Mars – where they form, for example, how they develop, how long they last, what kind of dust they pick up Are, and how they vary from place to place.
They can also reveal wind speed and duration, which, in combination with meteorological readings, can help scientists learn more about Martian weather, and how the dust devils fit into it.
Curiosity is currently the only operational rover on Mars (the Insight is a stationary lander), so whatever surface information Martial Dust can shine on devils is very limited. Mars also has operational orbiters, which cover a lot of ground.
These have occasionally caught the dust devils in action from space, as well as many, many tracks that they have left after retreating.