About a month ago, NASA published pictures of a dust devil on Mars that, with its 30 meters in diameter and about 800 meters (about half a mile) of height, looked really impressive. On March 14, however, the Mars Reconnaissance Orbiter (MRO) discovered another dust devil really huge in comparison with which the old one looks like a small whirlwind.
On Mars, there was just the summer solstice in the northern hemisphere, so that in this period it’s heated by the Sun with the maximum intensity. As in the previous discovery, keeping under observation the plain known as Amazonis Planitia, the Mars Reconnaissance Orbiter photographed with its High Resolution Imaging Science Experiment (HiRISE) a dust devil.
Astronomers determined its height examining the photographs transmitted by the Mars Reconnaissance Orbiter and established that it’s about 20 km (about 12 miles) high with a column diameter of about 70 meters (about 75 yards). That’s the size of a large tornado on Earth!
On Earth, dust devils are much smaller, rarely exceeding a few hundred meters in height. Instead, thanks to the lower density of Martian atmosphere and consequently the lower mass of the column, on the red planet there can be dust devils which have not only very wide columns but particularly ones that rise to considerable heights.
Despite its size, for the astronauts during a possible mission to Mars a dust devil of that kind wouldn’t be as dangerous as tornadoes are on Earth. Again, we must take into account that the Martian has a much lower density than the Earth’s. Despite the size of the dust devil and the speed of the air stream, it’s too rarefied to cause damage comparable to those of an Earth’s tornado, even a much smaller one.
The great danger posed by a dust devil would be caused by the sand. In fact, it tends to infiltrate all installations and vehicles built or brought to Mars and to have an action of erosion on any manufacts, including space suits of the astronauts who should be invested by a dust devil. In short, it’s a show better watched in pictures from a safe distance!