The interstellar comet 3I/ATLAS, discovered in July 2025 by the ATLAS telescope in Chile, approaches the Sun without official statements from NASA. Astronomers from several countries question the lack of updates from the American space agency, which has been monitoring the object for months. The hyperbolic trajectory confirms its origin outside the Solar System, the third recorded case. The silence comes amid observations that reveal atypical chemical compositions, such as high concentrations of carbon dioxide.
Experts highlight that NASA, despite financing the ATLAS system, has not released recent images of its probes on Mars. The comet passed close to the red planet in October 2025, about 30 million kilometers away. Agencies including the European Space Agency have released preliminary data, but the absence of American details fuels speculation. Perihelion, the closest point to the Sun, is scheduled for October 30, 2025.
The minimum distance to Earth will be 1.8 astronomical units, without risk of collision. However, the composition of the core, estimated to be between 300 meters and 5.6 kilometers in diameter, remains underexplored by NASA.
- Hubble Space Telescope observations indicate dust plume and subtle tail.
- James Webb Space Telescope data detects carbon monoxide and traces of nickeluel.
- Spectroscopy reveals water vapor at unexpected distances from the Sun.
Discovery and orbit of 3I/ATLAS
Astronomers confirmed the interstellar nature of 3I/ATLAS shortly after its detection on July 1, 2025. The ATLAS telescope, funded by NASA, captured the object 670 million kilometers from the Sun. Its speed of 209 thousand kilometers per hour distinguishes it from local comets.
The comet follows an open orbit, indicating a unique passage through the Solar System. It emerged from the direction of the Sagittarius constellation and is expected to return to interstellar space after March 2026. Preliminary observations from NASA’s TESS satellite suggest activity since May 2025.
The lack of updates from the American agency contrasts with releases from the ESA. Probes like Mars Express recorded the Martian flyby on October 3.
Chemical composition reveals peculiarities
Spectroscopic analyzes indicate predominant carbon dioxide in the comet’s coma. This proportion, eight times greater than water, differs from objects in the inner Solar System. Observatories in Chile and Hawaii have detected nickel emission lines without associated iron.
The James Webb Space Telescope, in August 2025, identified volatile compounds such as carbon monoxide. These elements suggest formation in a distant protoplanetary disk. The observed negative polarization alters light reflection, a rare trait.
Observations from international agencies fill in the gaps
The European Space Agency coordinated missions with Mars Express and ExoMars Trace Gas Orbiter. Images from October 7, 2025 show an elongated structure without evident fragmentation. The Hope probe, from the United Arab Emirates, contributed local magnetic field data.
ESA’s Juice Jupiter Observatory plans monitoring in November 2025. Ground-based telescopes in the Southern Hemisphere will track the object until September. China, via Tianwen-1, has captured ultraviolet spectra, but is awaiting processing.
These international contributions add up to more than 500 hours of collective observation. Collaboration accelerates analysis without relying exclusively on US resources.
Anomalies in comet activity
3I/ATLAS exhibits gas ejection facing the Sun, opposite to the solar sublimation pattern. Photometric brightness pulses every few hours, with no correlation to known rotation. Absence of dust outbreaks, despite the solar proximity, maintains stable levels.
Studies indicate a mass 1,000 to 10,000 times greater than expected for a similar size. Estimated ages range from 7 to 14 billion years, predating the Solar System. Natural orbital probability stands at 0.005 percent.
Expectations for the upcoming perihelion
The comet will reach 1.4 astronomical units from the Sun on October 30, 2025. Telescopes like Hubble prepare ultraviolet spectroscopy for emitted gases. Post-perihelion monitoring will track exit from the Solar System.
Reappearance in December 2025 will allow terrestrial targeting. Observatories in Chile adjust equipment for low light. The study window offers data on interstellar evolution.
Trajectory and likely origins
Orbital models point to its origin in the thin or thick disk of the Milky Way. Gravitational influences from nearby stars altered the path. Bayesian simulations calculate odds of artificial origin, but prioritize natural hypotheses.
Passage by Jupiter in March 2026 may modify final speed. Current distance to the planet is 210 million kilometers.
Contributions from space telescopes
Hubble captured images on July 21, 2025, 445 million kilometers from Earth. Details reveal an irregular core with a 10-kilometer coma. Swift Observatory detected hydroxyl in UV, confirming water vapor.
Gemini North recorded cyanide emissions in October. These observations add up to spectra of 20 distinct wavelengths.
