On January 21, 2024, a European orbiter recorded a stunning view of Mars at sunset. The images showcase the planet’s layered atmosphere in incredible detail. According to a new study, this view was captured using the ExoMars Trace Gas Orbiter (TGO) flying about 250 miles (400 kilometers) above Terra Cimmeria, revealing the rich textures of the Martian atmosphere.
The camera system, known as CaSSIS, provided clear images of the atmosphere from the planet’s shadow, where backlit layers emerged sharply against the twilight sky. The study highlighted five vertical slices of the atmosphere, each about 2.2 miles (3.5 kilometers) wide. These slices display the atmosphere’s layered structure, ranging in altitude from 9 to 34 miles (14 to 56 kilometers).
Nicolas Thomas, the principal investigator from the University of Bern, explains that his research focuses on how planetary imaging can unveil the effects of dust during Martian sunsets. Interestingly, the camera can spot small variations in color and brightness within these atmospheric layers.
As the sun sets on Mars, twilight produces a unique scattering of light. Blue wavelengths are amplified as they scatter off dust particles, creating stunning blue hues in the Martian sky. Mark Lemmon, a scientist with NASA, noted that as the blue light scatters off the dust, it tends to remain close to the sun’s direction. This phenomenon is part of what gives Mars its striking sunsets, which have drawn comparisons to Earth’s own colorful evenings.
Color trends in the atmosphere suggest that aerosols, tiny particles like dust or ice, tend to diminish in size with higher altitudes. Above around 27 miles (43 kilometers), some layers transition to a red hue, indicating changes in composition and size. This nuanced understanding of the atmosphere is crucial for climate models, as past profiles from Mars Climate Sounder show seasonal dust patterns and ice caps that fluctuate with changing weather conditions.
The process of capturing these remarkable images involved CaSSIS rotating its detector to catch the edge of Mars while traveling at approximately 2 miles per second (3.2 kilometers per second). The perfect angle for bright forward scattering allowed the researchers to gather five detailed datasets during a four-minute window, enhancing our understanding of the atmosphere’s structure.
Future plans for Mars include repeating these observations about once a month to create a comprehensive atlas of the Martian atmosphere. Researchers aim to uncover why some layers shift in color and how particle sizes vary from the equator to the poles. These insights will enhance our grasp of Mars’ climate and atmosphere.
The full findings can be explored in the detailed report published in Science Advances.
As exploration continues, Mars is proving to be more than just a barren landscape. It reveals layers of complexity in its atmosphere that provide vital clues for understanding its past and planning future missions.
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