NASA Releases Images of Interstellar Comet 3I/ATLAS Captured by Mars Missions
NASA has finally released stunning images of the third interstellar object (ISO) to visit our Solar System, known as 3I/ATLAS, which were captured by several missions currently operating at Mars. The images, taken by the Mars Reconnaissance Orbiter (MRO), the Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiter, and the Perseverance rover, provide an unprecedented close-up view of this mysterious visitor from beyond our solar system.
In early October 2025, 3I/ATLAS made its closest approach to Mars, coming within 30 million km (18.6 million mi) of the Red Planet. This flyby placed the comet within view of several missions operated by NASA, the European Space Agency (ESA), and the China National Space Agency (CNSA). While the ESA and CNSA promptly released their images, NASA's data release was delayed due to a government shutdown.
High-Resolution Images from the Mars Reconnaissance Orbiter
The MRO captured visible light images of 3I/ATLAS on Oct. 2nd using its High-Resolution Imaging Science Experiment (HiRISE) camera when the comet was approximately 0.2 astronomical units (AUs) away. To obtain these images, the orbiter had to perform a special maneuver, rotating to aim the camera at the celestial object.
"Observations of interstellar objects are still rare enough that we learn something new on every occasion. We're fortunate that 3I/ATLAS passed this close to Mars," said Shane Byrne, HiRISE principal investigator at the University of Arizona.
The HiRISE images, among the closest views any spacecraft or telescope is expected to obtain of 3I/ATLAS, will help scientists better estimate the comet's size and the color of particles in its core. An annotated version of the image indicates that the comet and its gaseous envelope measure approximately 1500 km (932 mi) in diameter.
Ultraviolet Observations by MAVEN
The MAVEN orbiter captured images of 3I/ATLAS using its Imaging Ultraviolet Spectrograph (IUVS) over a ten-day period from Sept. 27th to Oct. 7th. These high-resolution UV images provided the most detailed breakdown of the comet's chemical composition, establishing upper limits on the hydrogen-to-deuterium ratio and other chemical data that could offer clues about its origin.
An annotated composite image released by NASA identifies three hydrogen sources detected by MAVEN's IUVS camera: atmospheric hydrogen, interplanetary hydrogen, and hydrogen released from the comet's outgassing water.
"The images MAVEN captured truly are incredible," said Shannon Curry, MAVEN's principal investigator at the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder. "The detections we are seeing are significant, and we have only scraped the surface of our analysis."
Perseverance Rover Captures Faint Image from Mars Surface
NASA's Perseverance rover also managed to catch a glimpse of 3I/ATLAS from its position inside the Jezero Crater on Oct. 4th. Using its Mastcam-Z camera, the rover captured two images showing the comet as a faint smudge against a background starfield. Due to the object's faintness as seen from the surface, extremely long exposure times were necessary, resulting in stars appearing as streaks in the sky.
Comet's Evolving Behavior and Future Observations
Since reemerging from behind the Sun, 3I/ATLAS has exhibited new and intriguing behavior, including:
- A dramatic increase in brightness
- New ultraviolet and X-ray activity
- A more pronounced color
Scientists are eager to continue studying this rare interstellar visitor as it makes its way through our solar system. 3I/ATLAS will make its closest approach to Earth on Friday, Dec. 19th, 2025, at a distance of nearly twice the separation between the Earth and the Sun (2 AUs), posing no threat to our planet.
The images captured by NASA's Mars missions provide invaluable data for understanding the nature and origin of interstellar objects like 3I/ATLAS. As more advanced telescopes, such as the ESA's upcoming Comet Interceptor mission, come online in the coming years, astronomers will be better equipped to study these enigmatic visitors from distant star systems, shedding light on the diversity and evolution of matter across the cosmos.
