New global images of Mars from NASA鈥檚 Mars Atmosphere and Volatile Evolution (MAVEN) mission being led by CU Boulder show the ultraviolet glow from the Martian atmosphere in unprecedented detail, revealing dynamic, previously invisible behavior.
They include the first images of 听鈥渘ightglow鈥� that can be used to show how winds circulate at high altitudes. Additionally, dayside ultraviolet imagery from the spacecraft shows how ozone amounts change over the seasons and how听afternoon clouds form over giant Martian volcanoes. The images were taken by the Imaging UltraViolet Spectrograph (IUVS) on MAVEN.
鈥淢AVEN obtained hundreds of such images in recent months, giving some of the best high-resolution ultraviolet coverage of Mars ever obtained,鈥� said CU Boulder Professor Nick Schneider of the Laboratory for Atmospheric and Space Physics (LASP). Schneider is presenting new MAVEN results Oct. 19 at the American Astronomical Society Division for Planetary Sciences meeting in Pasadena, California.
CU Boulder designed and built the IUVS instrument and the Langmuir Probe and Waves experiment for the MAVEN mission. CU Boulder Professor Bruce Jakosky of LASP is the mission鈥檚 principal investigator and the university is leading science operations as well as public education and outreach for the mission.
Nightside images show ultraviolet (UV) 鈥渘ightglow鈥� emission from nitric oxide (abbreviated NO). Nightglow is a common planetary phenomenon in which the sky faintly glows even in the complete听absence of external light. The 鈥渘ightside鈥� atmosphere听of Mars emits light听in the ultraviolet due to chemical reactions that start on its dayside.
Ultraviolet light from the sun breaks down molecules of carbon dioxide and nitrogen, and the resulting atoms are carried around the planet by high-altitude wind patterns that encircle the planet. On the nightside, these winds bring the atoms down to lower altitudes where nitrogen and oxygen atoms collide to form nitric oxide molecules. The recombination releases extra energy, which comes out as ultraviolet light.
Scientists predicted NO nightglow听at Mars, and prior missions detected its presence, but MAVEN has returned the first images of this phenomenon in the Martian atmosphere. Splotches and streaks听appearing in these images occur where NO recombination is enhanced by winds. Such concentrations are clear evidence of strong irregularities in high altitude winds and circulation patterns on Mars.
These winds control how the Red Planet鈥檚 atmosphere responds to its very strong seasonal cycles.听These first images will lead to an improved determination of the circulation patterns that control the听behavior of the atmosphere from approximately 37 to 62 miles (about 60 to 100 kilometers) high.
Dayside images听show the atmosphere and surface near the south pole of Mars in听unprecedented听ultraviolet detail. They were obtained as spring comes to the southern听hemisphere. Ozone is听destroyed when water vapor is present, so ozone accumulates in the winter polar region where the water vapor has frozen out of the atmosphere.
The images show ozone lasting into spring, indicating that global winds are inhibiting the spread of water vapor from the rest of听the planet into听winter听polar regions.听Wave patterns in the images, revealed by UV absorption from ozone concentrations, are听critical to understanding the wind patterns, giving scientists an additional means to study the chemistry and global circulation of the atmosphere.
MAVEN observations also show听afternoon cloud formation over the听four giant volcanoes on Mars, much as clouds form over mountain ranges on Earth. The tallest, Olympus Mons is 88,000 feet, more than three times the height of Mt. Everest.
IUVS images听of cloud formation are among the best ever taken showing the development of clouds throughout the day. Clouds are a key to understanding a planet's energy balance and water vapor inventory, so these observations will be valuable in understanding the daily and seasonal behavior of the atmosphere.
鈥淐louds form on every planet in our solar system with enough atmosphere, often involving conditions or ingredients not found on Earth,鈥� said Schneider. 鈥淏ut these Mars clouds, forming over tall mountains in the afternoon, are surprisingly familiar,鈥� said Schneider. 鈥淧eople think of Mars as completely unlike Earth, but these scenes of afternoon cloud buildup over the mountains remind me of Colorado.鈥�
鈥淢AVEN's听elliptical orbit is just right,鈥� said CU Boulder Research Associate Justin Deighan of LASP, who led the observations. 鈥淚t 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.鈥�
NASA鈥檚 Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN project and provided two science instruments for the mission. The University of California at Berkeley鈥檚 Space Sciences Laboratory also provided four science instruments for the mission. Lockheed Martin built the spacecraft and is responsible for mission operations. NASA鈥檚 Jet Propulsion Laboratory in Pasadena, California, provides navigation and Deep Space Network support, as well as the Electra telecommunications relay hardware and operations.
