Scientists are intensifying scrutiny of the interstellar visitor 3I/ATLAS, the third-known object of its kind to enter the Solar System. Recent developments include refined trajectory measurements using data from Mars, close-range images captured by NASA’s Perseverance rover, and resurging debate about whether the object’s behavior might hint at artificial propulsion.
Sharpening the Trajectory with Mars-Based Observations
A major leap in understanding 3I/ATLAS came when the European Space Agency (ESA) leveraged data from its Mars-based spacecraft, the ExoMars Trace Gas Orbiter (TGO), to dramatically improve predictions of the object’s path. As the comet passed roughly 30 million kilometers from Mars in early October, the TGO observed it from a vantage point unavailable to Earth-based telescopes.
By combining Mars-based data with terrestrial observations, scientists reduced the trajectory uncertainty by a factor of ten. This refinement is critically important for accurate future tracking and for informing planetary defense approaches, although officials emphasize that 3I/ATLAS poses no threat.
NASA’s Perseverance Rover Captures a Historic Image
Simultaneously, NASA’s Perseverance rover, stationed on Mars, recorded a striking image of 3I/ATLAS using its navigation camera (Navcam). The picture appears as a long streak in a composite of hundreds of frames taken over approximately ten minutes—a result of the object’s rapid motion across the Martian sky during the exposure.
Astrophysicist Avi Loeb of Harvard, who has been closely following 3I/ATLAS, interpreted the streak effect as a motion blur rather than a physical structure. He argues that individual snapshot frames, each only a few seconds long, would show 3I/ATLAS as a compact spot rather than a streak.
Composition Anomalies: Gas Jets, Metal Emissions, and Debate
Earlier observations revealed intriguing and unusual behavior by the object. Observers reported complex jets and anti-solar streams, meaning some ejections appeared to point toward the Sun rather than away from it—a highly unusual feature for a comet.
Loeb has proposed a controversial hypothesis: these jets might be more than cometary outgassing. Instead, they could represent thrusters—suggesting 3I/ATLAS might be a technological spacecraft utilizing controlled propulsion to accelerate away from the Sun after its perihelion.
Adding to the mystery, Loeb has pointed to the detection of nickel tetracarbonyl—a metal compound rare in natural contexts but common in industrial processes. He contends that such output, paired with the anti-tail behavior, supports his “technosignature” theory.
Scientific Pushback and Natural Explanations
The wider scientific community has largely rejected Loeb’s more speculative interpretation. NASA scientists have publicly stated that 3I/ATLAS behaves like a natural comet. Researchers note that while the jets and acceleration are unusual, they can be explained by cometary physics without invoking artificial propulsion.
In particular, earlier analyses suggest the anti-solar tail could result from a stream of larger dust grains less affected by solar radiation, rather than from any rocket-like exhaust.
Chemical Signature and Coma Composition
Scientific observations continue to shed light on the object’s composition. A recent study using the James Webb Space Telescope (JWST) indicates that the comet’s coma is dominated by carbon dioxide (CO₂), along with water vapor, dust, and trace amounts of other molecules. Notably, the CO₂/H₂O ratio in 3I/ATLAS appears unusually high—far above what is typical for most Solar System comets—suggesting a nucleus composition that may reflect its interstellar origin.
Polarimetric measurements also show an extreme negative polarization, a feature not commonly seen in either asteroids or comets native to our solar system. These data hint that 3I/ATLAS could belong to a new class of interstellar object, or at least one that challenges familiar comet models.
Tension Over Data Access and Transparency
The debate over 3I/ATLAS has also stirred controversy about access to data. Loeb has publicly criticized NASA for not releasing high-resolution images from the HiRISE camera on the Mars Reconnaissance Orbiter, alleging that critical observations are being withheld. He claims the images could shed light on whether the object’s non-gravitational acceleration is consistent with natural outgassing or something more intriguing.
NASA, for its part, maintains that the data are being evaluated and that no credible sign of threat or alien origin has been confirmed.
What Lies Ahead
As 3I/ATLAS continues its journey out of the inner Solar System, astronomers are keeping a close eye. The refined orbit determined by ESA enables more precise instrument targeting for ground- and space-based observatories. The Perseverance images offer a rare stereo perspective of an interstellar visitor. And chemical, photometric, and polarimetric studies may help clarify whether 3I/ATLAS is simply a very unusual comet—or something altogether more extraordinary.
For now, the consensus in the broader scientific community leans toward a natural origin. But the unusual features identified by Loeb and his collaborators continue to drive debate and more observation, keeping 3I/ATLAS firmly in the spotlight of planetary science and interstellar research.
