A Martian volcano, Arsia Mons, rises above the clouds in a stunning newly-released panoramic image captured by the Mars Odyssey Orbiter, revealing a peak higher than any terrestrial volcano.
Arsia Mons reaches 12 miles above the Martian surface, twice as tall as Hawaii’s Mauna Loa, the tallest volcano on Earth, creating a dramatic image as it emerges from heavy clouds over the Red Planet.
The latest phase of Odyssey’s more than two-decade mission aims to capture valuable information about the Martian atmosphere, of critical interest to future crewed landing missions.
Tharsis Mountains
Arsia Mons is part of a mountain range called the Tharsis Montes, alongside two other volcanoes, Ascraeus Mons and Pavonis Mons. Arsia is the southernmost of the three, which makes a chain in the space between the largest volcano in our solar system, Olympus Mons, to the west and the Valles Marineris, a long stretch of canyons, to the east. The range is named after the Tharsis region in which it is located, close to Mars’ equator.
Despite being discovered back in 1971 by the Mariner 9 spacecraft, never before have any of the Tharsis Montes volcanoes been imaged along the horizon. Instead of Mars’ predominant carbon dioxide clouds, the three peaks are surrounded by clouds composed of water ice, which are most noticeable in the early morning.
Mars Odyssey Orbiter
In the more than two decades since its 2001 launch, the Mars Odyssey rover has become the longest-running orbiter mission to an extraterrestrial world. Despite its lengthy operational period, the orbiter continues to break new ground, with the present imaging task beginning in just 2023, with four high-altitude Martian horizon images. Capturing these panoramas required the Odyssey to rotate 90 degrees to observe their entire expanse.
Odyssey’s THEMIS camera, capable of detecting both visible and infrared light, captured the expansive views, as the instrument is versatile enough to also collect observations of the Martian atmosphere and objects in it, such as the moons Phobos and Deimos. The infrared imaging captured by THEMIS provides crucial data for researchers detecting underground ice on the Red Planet, as any local water supplies will be valuable assets to future crewed missions.
“We picked Arsia Mons hoping we would see the summit poke above the early morning clouds. And it didn’t disappoint,” said Jonathon Hill of Arizona State University in Tempe, operations lead for THEMIS.
The Changing Martian Atmosphere
Arsia Mons was spotted on May 2, 2025, as the team sought to capture interesting surface features during their investigation of Mars’ upper atmosphere. The series of images displays seasonal changes, as the clouds of dust and water ice change over time.
“We’re seeing some really significant seasonal differences in these horizon images,” said planetary scientist Michael D. Smith of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s giving us new clues to how Mars’ atmosphere evolves over time.”
Arsia holds the heaviest cloud cover of the three peaks in the Tharsis Mountains chain, formed by air expanding and then rapidly cooling as it travels up the volcano. During the aphelion, the period when Mars is at its greatest distance from the sun, the cloud cover grows even denser, part of a Martian equatorial ring called the aphelion cloud belt.
With an eye toward crewed Mars missions in the coming decades, unraveling the composition of these unique clouds offers important data for understanding Martian weather, which will also help to promote safe landings for future missions.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.