While extraterrestrial whirlwinds known as dust devils are a common feature on the surface of Mars, it is rare for us to get to watch one.
However the NASA Mars rover Opportunity was fortunate enough to spot one from the rim of the Endeavour Crater. Images beamed back to Earth show rover tracks, Martian geology and the amazing dust devil.
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NASA rover spots dust devil on Mars
Opportunity was working its way up the Knudgsen Ridge on its way to Marathon Valley when it spotted the phenomenon. The region is of great interest as research has suggested that clays may be present there.
The clays were created due to chemical processes in ancient surface water, so scientists believe they could find out more about Mars’ wet past if they study them. However on March 31 Opportunity took a glance over its shoulder and spotted the amazing dust devil winding its way across the valley below.
The NASA rover hasn’t seen many dust devils despite the fact that it has been on Mars for 12 years. However sister rover Spirit studied the phenomenon in great depth in the Gusev Crater.
Dust devils could affect Martian climate
Spirit got stuck in a sand trap and scientists lost communication with the rover in 2010. Since then scientists have mainly seen dust devils through the lens of the High-Resolution Imaging Science Experiment (HiRISE) camera on board NASA’s Mars Reconnaissance Orbiter (MRO).
Martian dust devils come about in the same way as their terrestrial cousins. Sunlight heats a thin layer of air above the ground, causing it to rise. As it starts to rotate a small pocket of low pressure forms and turns into a fast-spinning vortex, which sucks dust from the surface and reveals darker material underneath.
Scientists believe that due to the thin Martian atmosphere the dust devils are important for dust cycling and have a profound influence on the climate.
“The Martian air is so thin, dust has a greater effect on energy transfers in the atmosphere and on the surface than it does in Earth’s thick atmosphere,” said Udaysankar Nair of the University of Alabama in Huntsville (UAH), who studied the phenomenon.
First manned mission to Mars in around 10 years?
These mini-tornadoes also help Martian rovers to continue working. As they spin over the solar panels on top of the rover, they clean away accumulated dust and give the rover a much-needed power boost so that it can continue its study.
Dust devils can reach far larger sizes as tornadoes on Earth, up to 12 miles in height. Scientists are just beginning to understand how they get so large and the exact effect they have on Mars’ climate.
“To start a dust devil on Mars you need convection, a strong updraft,” said atmospheric science graduate Bryce Williams, of the University of Alabama in Huntsville (UAH), at the American Geophysical Union’s fall meeting in San Francisco in 2014.
“We looked at the ratio between convection and surface turbulence to find the sweet spot where there is enough updraft to overcome the low level wind and turbulence,” said Williams. “And on Mars, where we think the process that creates a vortex is more easily disrupted by frictional dissipation — turbulence and wind at the surface — you need twice as much convective updraft as you do on Earth.”
The dust devil is a fascinating sight and one that the first human visitors to Mars will get to see first hand. NASA predicts that the first manned mission to the Red Planet could happen in the 2030s.