NASA missions capture multi-platform views of interstellar comet 3I/ATLAS

NASA is conducting a distributed observation campaign of interstellar comet 3I/ATLAS, the third confirmed object from outside the solar system to pass through the Sun’s gravitational environment.

The campaign incorporates imagery and data from spacecraft positioned at Mars, near the Sun, and throughout the inner and outer solar system. 3I/ATLAS was discovered on July 1 by the ATLAS telescope in Chile and will reach its closest approach to Earth at approximately 273 million km (170 million miles) on December 19.

Mars-based observations

The closest images obtained so far were recorded from Mars orbit. The comet passed the planet earlier in the northern-hemisphere autumn at a distance of roughly 30 million km (19 million miles).

The Mars Reconnaissance Orbiter captured high-resolution images of the coma from this geometry, while MAVEN obtained ultraviolet measurements relevant to volatile composition. A faint surface-level detection was also made by the Perseverance rover.

Near-Sun vantage points

NASA’s heliophysics spacecraft were used to observe the comet during a period when its trajectory placed it close to the apparent position of the Sun as seen from Earth. STEREO tracked the comet from 11 September to 2 October.

The ESA/NASA SOHO mission imaged it between October 15–26. Data from the PUNCH mission, launched earlier in 2025, captured the developing tail in a sequence acquired from late September to early October, consistent with the PUNCH team’s published observational interval.

These missions provide lines of sight that are inaccessible from ground-based observatories during solar-conjunction periods. NASA notes that this is the first coordinated effort by its heliophysics fleet to purposefully observe an object known to originate in another stellar system.

Observations from deep-space missions

The Psyche spacecraft obtained four sets of images of 3I/ATLAS on September 8–9 from a distance of around 53 million km (33 million miles) while the Lucy spacecraft recorded a series of exposures on September 16 from roughly 386 million km (240 million miles), later stacked to increase signal and resolve the faint coma and tail.

Additional telescope observations

Hubble obtained imagery of the comet later in July, followed by observations in August from the James Webb Space Telescope and from SPHEREx.

JWST spectroscopy indicates a coma dominated by carbon dioxide, with a CO₂/H₂O ratio among the highest measured in any observed comet, while SPHEREx coverage contributes constraints on volatile abundances and dust scattering properties.

Trajectory and outlook

3I/ATLAS remains faint and will not reach naked-eye visibility. Its hyperbolic orbit confirms an origin outside the solar system.

After its closest Earth approach in December, the comet will continue outward, passing the orbit of Jupiter in spring 2026 before returning to interstellar space. Continued monitoring by NASA spacecraft is planned as viewing geometries allow.

Reet Kaur

I’m a science journalist and researcher at The Watchers, contributing to the Epicenter edition, where I cover peer-reviewed scientific research and emerging discoveries across Earth and space sciences. With a background in astronomy and a passion for environmental science, I’ve worked in shark and coral conservation in Fiji, conducting reef and shark-behavior research, contributing to mangrove restoration, and earning PADI Open Water and Coral Reef Certifications. I bring a blend of scientific rigor and storytelling to illuminate the discoveries shaping our planet and beyond.

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