The phenomenon, known as airglow (alternatively termed dayglow or nightglow depending on the time), is not unique to Mars and also occurs on Earth.Though it bears certain resemblances to the northern lights, or aurora, found onEarth, the green glow observed in Mars’ atmosphere is a distinct phenomenon with distinct underlying causes.
According to ESA, Nightglow “occurs when two oxygen atoms combine to form an oxygen molecule”.
On Mars, this phenomenon occurs at an altitude of around 31 miles (50 km). In contrast, auroras are generated when charged particles from the sun interact with Earth’s magnetic field.
For about 40 years, scientists have speculated about the presence of airglow on Mars. However, the first confirmation came only a decade ago when ESA’s Mars Express orbiter observed the phenomenon in the infrared spectrum.
Subsequently, in 2020, researchers observed airglow in visible light using the TGO, but during Martian daylight rather than at night. Now, the phenomenon has been witnessed at night through TGO.
“These new observations are unexpected and interesting for future journeys to the Red Planet,” ULiège planetologist Jean-Claude Gérard,” said in an ESA statement.
“The intensity of the night glow in the polar regions is such that simple and relatively inexpensive instruments in Martian orbit could map and monitor atmospheric flows. A future ESA mission could carry a camera for global imaging. In addition, the emission is sufficiently intense to be observable during the polar night by future astronauts in orbit or from the Martian ground,” the statement read.
The ongoing examination of Mars’ nightglow, integral to the TGO mission, will provide scientists with valuable insights into the processes taking place within the Martian atmosphere.
“Remote sensing of these emissions is an excellent tool for probing the composition and dynamics of Mars’ upper atmosphere between 40 and 80 km [25 to 50 miles],” Benoit Hubert, a researcher at the Laboratory for Planetary and Atmospheric Physics (LPAP) at the University of Liège told the news outlet.
“This region is inaccessible to direct methods of measuring composition using satellites,” Hubert added.
Exploring Mars’ atmosphere not only contributes to scientific knowledge but also aids in the development of future spacecraft intended for the Red Planet. Enhanced comprehension of its density enables mission planners to construct satellites capable of withstanding the drag induced by the Martian atmosphere.
Additionally, this knowledge can inform the design of parachutes for safely lowering payloads to the surface of the Red Planet. The findings of the team’s research were published in the journal Nature Astronomy on November 9.