Nightglow in the Upper Atmosphere of Mars and Implications for Atmospheric Transport

• Published in: Science (American Association for the Advancement of Science) 2005-01, Vol.307 (5709), p.566-569
• Main Authors: Bertaux, Jean-Loup, Leblanc, François, Perrier, Séverine, Quemerais, E, Korablev, Oleg, Dimarellis, E, Reberac, A, Forget, F, Simon, P. C, Stern, S. A, Sandel, Bill
• Format: Article
• Language: English
• Subjects: Airglow; Altitude; Analysis; Astrophysics; Atmosphere; Atmospheric chemistry; Atmospheric circulation; Atoms; Carbon Dioxide; Carbon dioxide emissions; Earth; Electric waves; Electro-optical devices; Electromagnetic radiation; Electromagnetic waves; Electrooptical devices; Extraterrestrial Environment; Hydrogen; Mars; Mars (Planet); Nitric Oxide; Nitrogen; Observation; Observations; Ocean, Atmosphere; Oxygen; P branes; Radiation; Sciences of the Universe; Seasons; Spacecraft; Spectral bands; Spectrophotometry, Ultraviolet; Spectroscopy; Spectrum analysis; Temperature; Ultraviolet radiation; Ultraviolet Rays; Venus; Venus (Planet)
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1106957

We detected light emissions in the nightside martian atmosphere with the SPICAM (spectroscopy for the investigation of the characteristics of the atmosphere of Mars) ultraviolet (UV) spectrometer on board the Mars Express. The UV spectrum of this nightglow is composed of hydrogen Lyman [alpha] emission (121.6 nanometers) and the [gamma] and [delta] bands of nitric oxide (NO) (190 to 270 nanometers) produced when N and O atoms combine to produce the NO molecule. N and O atoms are produced by extreme UV photodissociation of O₂, CO₂, and N₂ in the dayside upper atmosphere and transported to the night side. The NO emission is brightest in the winter south polar night because of continuous downward transport of air in this region at night during winter and because of freezing at ground level.