MAVEN captures detailed ultraviolet images of Mars’ atmosphere
NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft has taken hundreds of high-resolution photos of the Red Planet’s atmosphere in ultraviolet light, revealing unprecedented details of its cloud formation and high-altitude wind circulation.
Captured over the last several months by MAVEN’s Imaging UltraViolet Spectrograph (IUVS), the images depicting cloud formation were processed in false color and compiled to create a movie of activity visible only in the ultraviolet.
Photos of the planet’s nightside show the phenomenon known as ultraviolet “nightglow”, in which the nightside of a planet exhibits a faint glow in spite of being in complete darkness.
On Mars, this glow is caused by the emission of nitric oxide (NO) resulting from chemical reactions occurring on the dayside of the planet. There, carbon dioxide and nitrogen molecules are broken down by ultraviolet sunlight, releasing atoms that are then carried around the planet by high-altitude winds.
Once on the nightside, these winds bring the nitrogen and oxygen atoms down to lower altitudes where they subsequently collide with one another in a process that reforms the nitric oxide molecules while releasing excess energy in the form of ultraviolet light.
Ultraviolet dayside images show both the surface and atmosphere of Mars’ south pole in vivid detail. Now entering spring, the south polar region contains deposits of ozone that accumulated during the winter when water vapor froze out of the atmosphere.
Global winds circling the planet are preventing the spread of water vapor from other parts of the planet into the south polar region.
Patterns of planet-wide winds are visible as wave patterns only in the ultraviolet, so these images are providing scientists with a new tool for understanding the Martian atmosphere’s chemistry and wind circulation.
Also visible in the dayside images are clouds forming over Mars’ four huge volcanoes, much like they form over volcanoes on Earth. Photos obtained on July 9–10, 2016, show the evolution of the clouds during a seven-hour period, which constitutes one-quarter of a Martian day.
These photos will play a key role in helping scientists better understand both daily and seasonal changes on the Red Planet because cloud patterns provide vital information about a planet’s water vapor and energy balance.
“MAVEN’s elliptical orbit is just right. 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,” said Justin Deighan, mission observation leader from the University of Boulder, Colorado.
The findings are all the more interesting because scientists did not expect to find any nightglow on Mars.
Blotchy areas and streaks in the images indicate Mars’ high-altitude winds have irregular circulation patterns. Because atmospheric responses to seasonal cycles are controlled by these winds, data from these images will be especially useful in helping scientists understand the way the Martian atmosphere behaves between 37 and 62 miles (60-100 km) above the surface.
Video Courtesy of NASA.gov Video
Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.