NASA’s longest-running mission to Mars has delivered an extraordinary side view of Arsia Mons, a colossal, long-extinct volcano rising from the Red Planet’s surface just before dawn. On May 2, as sunlight crept over Mars’ horizon, the Odyssey spacecraft captured this striking image of Arsia Mons breaking through a glowing band of greenish haze in the planet’s upper atmosphere.
Standing 12 miles high — nearly twice the height of Hawaii’s Mauna Loa — Arsia Mons emerges through a veil of fog, a monument to Mars’ ancient geological past. The image not only captivates visually but also offers valuable scientific insights.
Jonathon Hill, lead of Odyssey’s camera operations at Arizona State University, said, “We picked Arsia Mons hoping we would see the summit poke above the early morning clouds, and it didn’t disappoint.”
Odyssey’s New Horizon-Gazing Technique
To capture this view, Odyssey had to adjust its usual approach. Typically, the orbiter points its camera straight down to map Mars’ surface, but in the past two years, scientists began rotating it 90 degrees to look toward the horizon. This novel perspective helps researchers study seasonal changes in dust and ice clouds.
Though still an aerial view, this horizon perspective resembles how astronauts on the International Space Station see Earth’s curved edge meeting space. Odyssey flies about 250 miles above Mars, providing a similar vantage point.
The Towering Giants of the Tharsis Region
Arsia Mons is part of the Tharsis Montes, a trio of enormous volcanoes dominating Mars’ southern hemisphere. The Tharsis region hosts the largest volcanoes in the solar system. Due to the absence of plate tectonics on Mars, these giants grew far larger than any volcano on Earth.
The volcanoes often wear cloud covers in the early morning, especially water-ice clouds, which differ from Mars’ usual carbon dioxide clouds. Arsia Mons is the cloudiest among them.
Scientists have focused on a specific cloud formation over Arsia Mons, known as the Arsia Mons Elongated Cloud. Stretching 1,100 miles over southern Mars, this transient streak appears only for about three hours on spring mornings before dissipating in sunlight. It forms as strong winds are pushed up the volcano’s slopes.
Seasonal Cloud Patterns and New Atmospheric Clues
The cloud layer visible in Odyssey’s image is part of the aphelion cloud belt — a seasonal phenomenon draping the planet’s equator when Mars is at its farthest point from the Sun.
This marks Odyssey’s fourth side view since 2023 and the first to capture a volcano piercing through clouds.
NASA planetary scientist Michael D. Smith remarked, “We’re seeing some really significant seasonal differences in these horizon images. It’s giving us new clues to how Mars’ atmosphere evolves over time.”
What The Author Thinks
Odyssey’s ability to capture such a breathtaking and scientifically rich image speaks to how far Mars exploration has advanced. Viewing the planet’s horizon and its towering volcanoes through a different lens opens new pathways to understand Martian climate and atmospheric dynamics. These insights are vital not only for planetary science but also for future missions aiming to explore and possibly colonize Mars. The more we can observe subtle seasonal changes, the better prepared humanity will be to unravel Mars’ mysteries.
Featured image credit: U.S. Embassy Jakarta via Flickr
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