We now have the latest ultraviolet glow of planet Mars in images! The findings will be presented today, October 19, at the American Astronomical Society Division for Planetary Sciences meeting.
The images were taken as part of the Mars Atmosphere and Volatile Evolution mission (MAVEN). An Imaging UltraViolet Spectrograph (IUVS) was used to generate details of the hitherto-invisible dynamic occurrences on Mars. These images are hoped to help carve a better understanding of the seasons and wind circulation of the Martian world.
“MAVEN obtained hundreds of such images in recent months, giving some of the best high-resolution ultraviolet coverage of Mars ever obtained,” says Nick Schneider from the University of Colorado, Boulder.
“MAVEN’s elliptical orbit is just right,” says Justin Deighan of the University of Colorado, Boulder, who led the observations. “It rises high enough to take a global picture, but still orbits fast enough to get multiple views as Mars rotates over the course of a day.”
The images show off the nightglow, a phenomenon characterised by a faint glow of the sky in the absence of external light. It is used to understand high altitute circulation of winds.
The nightside images show how chemical reactions starting off on the dayside of Mars lead to its nightside atmosphere emitting light in the ultraviolet. Carbon dioxide and nitrogen molecules are first broken down into atoms by UV light from the sun. These atoms, then, move upwards around Mars by wind patterns. Then, on the nightside, the winds move the atoms to lower altitudes, resulting in the formation of nitric oxide molecules through the collision of nitrogen and oxygen atoms. The extra energy released in this reaction results in ultraviolet light.
Nightglow was previously thought not to exist on Mars, and sometimes the recombination of nitrogen and oxygen is not furthered by winds. The new findings, therefore, suggest great irregularities in the high altitude winds and circulation patterns of Mars. The images will, thus, shed more light on these occurrences on the planet.
Ultraviolet images also depict the change in the concentration of ozone over the different seasons. The dayside images were obtained when spring returned to the southern hemisphere of the planet. Ozone remained during that season, suggesting that the spread of water vapour into the polar regions was obstructed by global winds because ozone is, otherwise, destroyed by the presence of water vapour. This finding is deemed important to understand wind patterns, which will, in turn, help scientists study the Martian atmosphere in more details pertaining to chemistry.
We can also see afternoon clouds being formed above the volcanoes of Mars in the MAVEN images. This process is similar to cloud formation over mountain ranges on our own planet. This will hopefully enable researchers to find out about the energy balance and water vapour fluctuations of the planet, ultimately leading to a better understanding of the seasons of Mars.