China Publishes First Images of Interstellar Comet 3I/ATLAS Near Mars; NASA Photos Held by Shutdown

China shares first public images of interstellar comet 3I/ATLAS as it passed Mars

China has released the first publicly available images of the rare interstellar comet 3I/ATLAS after the object made a close approach to Mars, beating the United States to publication. Both China’s Tianwen-1 orbiter and NASA’s Mars Reconnaissance Orbiter (MRO) captured observations when the comet passed roughly 18 million miles from Mars on Oct. 3, but only the China National Space Administration (CNSA) has made its images public so far.

What the Tianwen-1 images show

CNSA said Tianwen-1’s High-Resolution Imaging Camera (HiRIC) — which has been operating around Mars since February 2021 — recorded a bright nucleus surrounded by an extensive coma spanning about 3,100 to 6,200 miles (5,000–10,000 km). In a statement, CNSA called this "the first attempt to photograph such a distant and relatively faint target (10,000 to 100,000 times darker than a target on the surface of Mars)" and highlighted the team’s feasibility assessment based on orbital geometry, brightness estimates and the orbiter’s payload capabilities.

"Comet characteristics of the celestial body are obvious in the image, which is composed of the comet's core and its surrounding coma, with a diameter of thousands of kilometers…Through these observations, researchers are further conducting in-depth research on Atlas," CNSA said.

Why NASA’s images aren’t public yet

NASA’s MRO also imaged 3I/ATLAS with its HiRISE camera, which has a 19.7‑inch aperture and can deliver sharper resolution than Tianwen-1’s 15.2‑inch HiRIC. Reports indicate MRO data could offer roughly three times the resolution of Hubble Space Telescope images taken on July 21. However, those MRO images remain unreleased amid a partial U.S. federal government shutdown that began Oct. 1 and has limited some agency operations.

Republican Rep. Anna Paulina Luna (Fla.) said she spoke with NASA about making the MRO images public and urged Acting Administrator Sean Duffy in a letter dated Oct. 31 to release the data despite the shutdown. NASA has indicated it will publish the images when the agency resumes normal operations.

Unusual properties and ongoing analysis

Harvard astronomer Avi Loeb, who has publicly called for release of the MRO photos and has previously speculated that 3I/ATLAS could be artificial, said on his blog he hopes higher‑quality HiRISE images will appear soon. Observatories that released post‑perihelion pictures — including the R. Naves Observatory — show a faint, roughly spherical glow with no obvious tail after the comet passed perihelion around Oct. 29–30.

Loeb calculated that more than 13% of the object’s mass may have been lost during the perihelion passage. He wrote that for a typical comet, that degree of mass loss would usually produce a large dust-and-gas coma shaped by solar radiation pressure and the solar wind into a distinct tail pointing away from the Sun. The apparent lack of a classic tail, along with the comet’s unusually large nucleus, high incoming speed, rapid brightening near perihelion, and a color shift toward bluer than the Sun, have been cited as anomalies worth further study.

Scientists are continuing to analyze the Tianwen-1 images, pending release of the higher‑resolution MRO data, to better understand the nature and behavior of 3I/ATLAS. Both sets of observations will help refine models of interstellar objects and their responses to close solar encounters.

Note: This article summarizes public statements by CNSA and reporting about NASA’s MRO; speculative interpretations (including those by individual researchers) remain unconfirmed until the full data are available.