This is an image of the ultraviolet ‘night glass’ in the Martian atmosphere. Green and white false colors represent the intensity of ultraviolet light, with white being the brightest. The night glass was measured at an altitude of about 70 kilometers by the Imaging UltraViolet Spectrograph instrument on NASA’s MAVEN spacecraft. A simulated view of the Marsbol is added digitally for context. The image shows an intense illumination in the night atmosphere of Mars. The lights come regularly after sunset on Martian evenings in the fall and winter seasons, and disappear by midnight. The lighting is caused by increased wind downwards which increase the chemical reaction, creating nitric oxide which causes the glow. Credit: NASA / MAVEN / Goddard Space Flight Center / CU / LASP
Large areas of the Martian night sky pulse in ultraviolet light, according to images from NASA‘s MAVEN spaceship. The results are used to elucidate complex circulation patterns in the Martian sphere.
The MAVEN team was surprised to find that the atmosphere pulsed exactly three times a night, and only during March‘spring and autumn. The new data also revealed unexpected waves and spirals over the winter poles, while the Mars Express spacecraft results also confirmed that this night glass was clear over the winter pole regions.
Mars’ night atmosphere glows and pulsates in this data animation from MAVEN observations of spacecraft. Green-white false color shows the enhanced illumination on Mars’ ultraviolet ‘night glass’, measured by MAVEN’s Imaging UltraViolet Spectrograph at an altitude of about 70 kilometers (about 40 miles). A simulated view of the Marsbol is added digitally for context, with ice caps visible at the wrist. Three night glass illuminations come across one rotation of Mars, the first much brighter than the other two. All three lights come shortly after sunset, appearing to the left of this view of the night side of the planet. The pulsations are caused by wind going down which improves the chemical reaction which becomes nitric oxide which causes the glow. Months of data were averaged to identify these patterns, indicating that they recur at night. Credit: NASA / MAVEN / Goddard Space Flight Center / CU / LASP
“The images from MAVEN provide our first global insight into atmospheric motions in the mid-atmosphere of Mars, a critical region where air currents carry gases between the lowest and highest layers,” said Nick Schneider of the University of Colorado Laboratory for Atmospheric and Space Physics (LASP), Boulder, Colorado. The illuminations occur where vertical wind gases lead to areas of higher density, whereby the chemical reactions increase the rate at which nitric oxide is created and the ultraviolet glow power. Schneider is instrument lead for the MAVEN Imaging Ultraviolet Spectrograph (IUVS) instrument that made these observations, and lead author of a paper on this study that was published on August 5, 2020, in the Journal of Geophysical Research, Space Physics. Ultraviolet light is invisible to the human eye but detected by specialized instruments.
The diagram explains the cause of Mars’ glowing night atmosphere. On the day of Mars, molecules are dragged apart by energetic solar photons. Global circulation patterns carry the atomic fragments to the nocturnal side, where winds downward increase the reaction rate for the atoms to reform molecules. The declining wind occurs in some seasons near the pulse and in the equatorial regions among others. The new molecules have extra energy that they emit as ultraviolet light. Credit: NASA / MAVEN / Goddard Space Flight Center / CU / LASP
“The ultraviolet glow usually comes from a height of about 70 kilometers (about 40 miles), with the brightest place about a thousand kilometers (about 600 miles), and is as bright in the ultraviolet as the northern lights of the earth, “said Zac Milby, also of LASP. “Unfortunately, the composition of Mars’ atmosphere means that these bright spots do not emit light at visible wavelengths that allow them to be seen by future Mars astronauts. Pity: the light patches would intensify every night after sunset over the world and drift across the sky at 300 kilometers per hour (about 180 miles per hour). ”
The pulsations discover the importance of planet-surrounding waves in the atmosphere of Mars. The number of waves and their velocity indicate that the middle atmosphere of Mars is influenced by the daily pattern of solar heating and disturbances of the topography of Mars’ enormous volcanic mountains. These pulsating spots are the clearest evidence that the waves of the middle atmosphere correspond to those known to dominate the layers above and below.
“MAVEN’s major discoveries of atmospheric loss and climate change demonstrate the importance of these large circulation patterns that transport atmospheric gases across the globe and from the surface to the edge of space.” said Sonal Jain, also of LASP.
This is an image of the ultraviolet ‘night glass’ in the Martian atmosphere over the South Pole. Green and white false colors represent the intensity of ultraviolet light, with white being the brightest. The night glass was measured at an altitude of about 70 kilometers by the Imaging UltraViolet Spectrograph instrument on NASA’s MAVEN spacecraft. A simulated view of the Marsbol is digitally added for context, and the faint white area in the center of the image is the polar ice cap. The image shows an unexpectedly bright glowing spiral in the night atmosphere of Mars. The cause of the spiral pattern is not known. Credit: NASA / MAVEN / Goddard Space Flight Center / CU / LASP
Next, the team plans to view nightglass “sideways”, instead of from top to bottom, with data used by IUVS looking just above the edge of the planet. This new perspective will be used to better understand the vertical winds and seasonal changes.
The Martian night glass was first observed by the SPICAM instrument on the European Space Agency’s Mars Express spacecraft. However, IUVS is a next-generation tool that is better able to map the glow of the night several times, finding patterns and periodic behaviors. Many planets including Earth have night glasses, but MAVEN is the first mission to collect as many images from a night glass of another planet.
Reference: “Imaging of Martian Circulation Patterns and Atmospheric Times Through MAVEN / IUVS Nightglow Observations” by NM Schneider, Z. Milby, SK Jain, F. González – Galindo, E. Royer, J.‐C. Gérard, A. Stiepen, J. Deighan, AIF Stewart, F. Forget, F. Lefèvre en SW Bougher, 5 August 2020, JGR Space Physics.
DOI: 10.1029 / 2019JA027318
The research was funded by the MAVEN mission. MAVEN’s principal investigator is based at the University of Colorado Laboratory for Atmospheric and Space Physics, Boulder, and NASA manages the MAVEN project. NASA explores our solar system and beyond, discovering worlds, stars and cosmic mysteries near and far with our powerful fleet of space and ground-based missions.
