Ultraviolet Imaging Shows Us Mars Like We've Never Seen It

by Kastalia Medrano
CU Boulder Laboratory for Atmosphere and Space Physics

For the first time, scientists have obtained images of Mars’s fabled “nightglow,” a mysterious atmospheric phenomenon on the Red Planet, that could help future Mars colonists understand how the Red Planet’s atmosphere functions.

NASA’s Mars Atmosphere and Volatile Evolution Mission (MAVEN) has been studying the Red Planet’s atmosphere since 2013, but on Monday, it had something big to report. During a press conference hosted by the American Astronomical Society, Nicholas Schneider of the University of Colorado, Boulder, presented recent images from the University’s Imaging UltraViolet Spectrograph (IUVS), that finally confirmed that Mars’s “nightglow” was a definite part of the planet’s atmosphere.

Nightglow refers to the chemical reactions taking place in Mars’s upper atmosphere — specifically with nitric oxide. It illuminates irregularities in the planet’s circulation (weather, basically), and the hundreds of new images provided by MAVEN mark the first time we’ve been able to observe it with anything like this kind of detail. Understanding Mars’s atmosphere is crucial to understanding how the planet’s meager water cycle works. There isn’t a lot of water, let alone oxygen, on the planet, but nightglow, and the planet’s other atmospheric factors, are still hugely important. Scientists previously suspected nitric oxide nightglow was real, but they’ve never been able to return images of it until now.

UC Boulder’s IUVS has been studying the loss of the Martian atmosphere, as well as the planet’s climate history, for the duration of the MAVEN’s orbits. The new set of images exhibits the power of imaging spectroscopy, wherein each pixel contains the full ultraviolet spectrum. It’s allowed the researchers to make insights into three main areas of Mars study: nightglow, ozone, and clouds.

Mars doesn’t have much atmosphere, and therefore not much oxygen, but that doesn’t mean that what it does have isn’t intriguing. Unlike the Earth, which presents the commonly known ozone holes, Mars exhibits ozone “piles” — pileups resulting from its different chemistry, and from how high-altitude winds carry atoms around the planet. The new images confirmed that the ozone accumulates in the polar vortex, as scientists believed, where there’s little water vapor; the hydrogen and oxygen molecules can destroy the ozone layer. The ozone turned out to extend further into the springtime than previously thought. The more we understand about the planets ozone, the more we understand about how water escapes from the surface.

As for clouds on Mars, they’re commonly composed of water ice crystals, and they allow the scientists observing them to trace the planets atmospheric flow. A brief video model, constructed from the data, showed the various points at which they tended to collect, particularly above geographic elements like volcanoes.

“Just pick your volcano and watch the growth of the clouds, Schneider said. “You can see this incredible expansion of the clouds over the course of just seven hours — they basically merge here in a cloud bank that must be a thousand miles across.”

You can see the clouds forming over four prominent volcanoes, just like how clouds gather over mountain ranges on Earth. Schneider said this is precisely the kind of data scientists want to plug into circulation models for cloud formation to test how well theyve interpreted the physics of it all, and to see how the energy of the planet shifts with the seasons.

Knowing the processes behind Mars’s atmosphere is critical for any plans to build and operate permanent outposts on the planet as the century unfolds. After all, just as we prefer having forecasts of the weather here on Earth, humans living on the Red Planet will almost certainly want to know what’s in store for them when they wake up for that day.

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