NASA's MAVEN mission has returned images showing the ultraviolet glow from the Martian atmosphere in unprecedented detail, revealing dynamic, previously invisible behaviour.
They include the first images of "nightglow" that can be used to show how winds circulate at high altitudes, NASA said in a statement on Tuesday.
Nightglow is a common planetary phenomenon in which the sky faintly glows even in the complete absence of external light
Scientists predicted nitric oxide (NO) nightglow at Mars, and prior missions detected its presence, but MAVEN has returned the first images of this phenomenon in the Martian atmosphere, the statement added.
Additionally, dayside ultraviolet imagery from the spacecraft shows how ozone amounts change over the seasons and how afternoon clouds form over giant Martian volcanoes.
"MAVEN obtained hundreds of such images in recent months, giving some of the best high-resolution ultraviolet coverage of Mars ever obtained," said Nick Schneider of the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder.
The images were taken by the Imaging UltraViolet Spectrograph (IUVS) on MAVEN.
Schneider will present these results on October 19 at the American Astronomical Society Division for Planetary Sciences meeting in Pasadena, California, which is being held jointly with the European Planetary Science Congress.
The Mars Atmosphere and Volatile Evolution (MAVEN) mission was launched in November 2013 to explore the Red Planet's upper atmosphere, ionosphere and interactions with the sun and solar wind.
Video shows images from MAVEN's Imaging UltraViolet Spectrograph were used to make this movie of rapid cloud formation on Mars on July 9-10, 2016. The ultraviolet colors of the planet have been rendered in false color, to show what we would see with ultraviolet-sensitive eyes. The movie uses four MAVEN images to show about 7 hours of Mars rotation during this period, and interleaves simulated views that would be seen between the four images. Mars' day is similar to Earth’s, so the movie shows just over a quarter day. The left part of the planet is in morning and the right side in afternoon.
Mars’ prominent volcanoes, topped with white clouds, can be seen moving across the disk. Mars’ tallest volcano, Olympus Mons, appears as a prominent dark region near the top of the images, with a small white cloud at the summit that grows during the day. Olympus Mons appears dark because the volcano rises up above much of the hazy atmosphere which makes the rest of the planet appear lighter. Three more volcanoes appear in a diagonal row, with their cloud cover merging to span up to a thousand miles by the end of the day. These images are particularly interesting because they show how rapidly and extensively the clouds topping the volcanoes form in the afternoon. Similar processes occur at Earth, with the flow of winds over mountains creating clouds. Afternoon cloud formation is a common occurrence in the American West, especially during the summer. Credits: NASA/MAVEN/University of Colorado