NASA has released a number of global ultraviolet images of Mars, constructed from data harvested by the agency's MAVEN spacecraft. The data will help scientists to understand the processes at play in the tenuous Martian atmosphere, including the means by which the Red Planet's enormous volcanoes become sheathed in cloud.
The Mars Atmosphere and Volatile EvolutioN (MAVEN) probe was launched in November 2013 with a mission to explore the Martian atmosphere. The data used in the new images was collected by the orbiter's Imaging Ultraviolet Spectrograph (IUVS) instrument, which was designed to characterize the Red Planet's upper atmosphere and ionosphere.
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In the newly released images, the ultraviolet light, which would ordinarily be invisible to human eyes, has been presented in false color.
Since its arrival around Mars in September 2014, MAVEN has been hard at work. Part of the new image release takes the form of an incredibly detailed ultraviolet view of the Martian south polar region, as seen by the orbiter on July 10, 2016. The data used to create the scene was harvested as the southern hemisphere of the Red Planet experienced its spring season.
Ultraviolet false color image of the Martian south polar region. The magenta smudge denotes concentrations of atmospheric ozone
By observing the UV signature of the polar regions as the southern hemisphere progressed through spring, NASA saw a build-up of ozone, indicated in magenta. The build-up comes about because water, which normally destroys ozone, freezes out of the atmosphere in winter. Even though spring would bring warmer temperatures to the pole and with it, ozone-busting water, the fact that ozone remained suggests that wind patterns were largely preventing water vapor from returning to the pole.
Also represented in the new release are the first-ever images of a Martian "nightglow" – a phenomenon that causes the side of a planet facing away from the Sun to gently glow with ultraviolet light. Whilst the phenomenon is named for the night, the process responsible for creating the glow begins on the day side of the planet, where ultraviolet light from the Sun breaks down molecules of carbon dioxide and nitrogen into their component atoms.
These atoms are then transferred to the night side of the planet thanks to strong, high-altitude winds. The newly deposited nitrogen and oxygen atoms then sink further down into the atmosphere, where they collide to form nitric oxide. As the atoms combine to create new molecules, excess energy is released in the form of ultraviolet light, which can be picked up by an orbiting spacecraft's spectrometer.
By observing this ultraviolet glow, MAVEN's science team was able to infer that splotches and lines present in the "nightglow" data point to irregularities in the circulation patterns of high-altitude winds. The new images should allow scientists a greater understanding of vital wind patterns that dictate the nature of the Martian atmosphere between 37 – 62 miles (60 – 100 km) above the Red Planet's barren surface.
Alongside the static images, NASA has released a brief nine-second video documenting seven hours of ultraviolet light data. Terrain on the left side of the planet in the video is experiencing morning conditions, while land on the right is experiencing afternoon, prior to slipping into the night side of the planet.
Three of Mars' massive volcanoes are prominently displayed in the video. The monstrous landmarks are easily discernible in the ultraviolet data by the white blotches of cloud that gather around their steep peaks. As the disk of the planet rotates, Olympus Mons, the tallest volcano on the Red Planet slips into view, appearing as a dark smudge.
As the Martian day progresses towards evening, the white clouds situated above the volcanoes grow exponentially. This continues until the clouds shrouding the three volcanoes combine into a single vast cloud spanning roughly 1,000 miles (1,609 km). Collecting data on cloud formations such as those seen in the video is valuable, as it helps scientists to understand the dynamic behavior of the Martian atmosphere, on daily, and even seasonal timescales.
Scroll down to view the NASA video created from data collected by MAVEN on July 9 – 10 2016.