Wide areas of Martian night sky pulse in ultraviolet light, according to images from NASAMAVEN SPACE SPACE. The results are being used to illuminate complex circulation patterns in the Martian atmosphere.
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 rods, while also confirming the results of the Mars Express spacecraft that this night light was brighter in the polar winter regions.
The atmosphere of the nights of Mars shines and pulsates in this animation of data from the observations of the spacecraft MAVEN. The false green to white color indicates the enhanced brightness of the Mars ultraviolet “bride” measured by Spectrograph UltraViolet MAVEN Images at an altitude of about 70 kilometers (approximately 40 miles). A simulated view of the Martian globe is added digitally for context, with ice caps visible at the poles. Three night glows occur during a rotation of Mars, the first much brighter than the other two. All three lights occur just after sunset, appearing to the left of this view from the planet’s night side. The pulsations are caused by falling winds which improve the chemical reaction by creating nitric oxide which causes glow. Months of data were average to identify these patterns, indicating that they recur overnight. Credit: NASA / MAVEN / Goddard Space Flight Center / CU / LASP
“MAVEN images provide our first global overview of atmospheric movements in the middle atmosphere of Mars, a critical region where air currents carry gases between the lower and upper layers,” Nick Schneider of the University of Colorado Laboratory told Atmospheric Physics and Space (LASP), Boulder, Colorado. Light bulbs occur when vertical winds carry gases to regions with higher densities, accelerating chemical reactions that create nitric oxide and enhance ultraviolet glow. Schneider is the instrument leader for the MAVEN Ultraviolet Imaging Spectrograph (IUVS) instrument that made these observations, and the lead author of a paper on this study that was published on August 5, 2020, in Journal of Geophysical Research, Space Physics. Ultraviolet light is invisible to the human eye, but detectable by specialized instruments.
“Ultraviolet light comes mainly from an altitude of about 70 kilometers (approximately 40 miles), with the brightest spot about a thousand kilometers (approximately 600 miles) beyond, and is as bright in ultraviolet as the northern lights of the Earth,” he said. Zac Milby, also of LASP. “Unfortunately, the composition of Mars’ atmosphere means that these bright spots do not emit light at apparent wavelengths that would allow them to be seen by future Mars astronauts. Too bad: bright patches would intensify upwards. “every night after sunset, and will dive through the sky at 300 kilometers per hour (about 180 miles per hour).”
The pulsations reveal the importance of the planet’s surrounding waves in the Martian atmosphere. The number of waves and their speed indicate that the middle atmosphere of Mars is influenced by the daily pattern of solar heating and disturbances by the topography of the large volcanic mountains of Mars. These pulsating dots are the clearest evidence that medium-wave waves match those known to dominate the upper and lower layers.
“MAVEN ‘s key findings on atmospheric loss and climate change show the importance of these vast patterns of circulation that transport atmospheric gases around the globe and from the surface to the edge of space.” said Sonal Jain, also of LASP.
Next, the team plans to look at the night wall “sideways”, rather than up and down, using data obtained from IUVS that looks slightly above the edge of the planet. This new perspective will be used to understand vertical winds and seasonal changes even more accurately.
Martian light night was first spotted by the SPICAM instrument on the European Space Agency’s Mars Express spacecraft. However, IUVS is a next-generation instrument that is better able to repeatedly describe the brightness of the nights, finding patterns and periodic behaviors. Many planets including Earth have night light, but MAVEN is the first mission to collect so many night light images of another planet.
Reference: “Images of Martian circulation patterns and atmospheric tides through larger night observations” by NM Schneider, Mr. Milby, SK Jain, F. González-Galindo, E. Royer, J.‐C. Gérard, A. Stiepen, J. Deighan, AIF Stewart, F. Forget, F. Lefèvre and SW Bougher, 5 August 2020, JGR Physics of Space.
DOI: 10.1029 / 2019JA027318
The research was funded by the MAVEN mission. The MAVEN lead investigator is based at the University of Colorado Laboratory for Atmospheric Physics and Space, Boulder, and NASA Goddard manages the MAVEN project. NASA is exploring our Solar System and beyond, discovering worlds, stars and cosmic mysteries near and far with our powerful fleet of space-based and earth-based missions.