China’s Tianwen‑1 photographed interstellar comet 3I/ATLAS during its early October flyby of Mars, capturing the nucleus and a coma from about 18 million miles (29 million km) away. The HiRIC camera recorded the comet’s track between Oct. 1–4 and a standalone image on Oct. 3. CNSA said the observations served both scientific goals and technical tests useful for future missions like Tianwen‑2.
China’s Tianwen‑1 Photographs Interstellar Comet 3I/ATLAS During Mars Flyby
China’s Tianwen‑1 photographed interstellar comet 3I/ATLAS during its early October flyby of Mars, capturing the nucleus and a coma from about 18 million miles (29 million km) away. The HiRIC camera recorded the comet’s track between Oct. 1–4 and a standalone image on Oct. 3. CNSA said the observations served both scientific goals and technical tests useful for future missions like Tianwen‑2.
15:51, 07.11.2025Science
China’s Tianwen‑1 Captures Images of Interstellar Comet 3I/ATLAS
China’s Mars orbiter Tianwen‑1 imaged the interstellar comet 3I/ATLAS as it made a close passage by Mars in early October, contributing valuable observations to the international effort to study this rare visitor from another star system.
What was observed
Between Oct. 1 and Oct. 4, Tianwen‑1 used its High‑Resolution Imaging Camera (HiRIC) to photograph the comet from roughly 18 million miles (about 29 million kilometers) away. CNSA released a sequence showing the comet’s track and a standalone image taken on Oct. 3 that reveal a compact nucleus surrounded by an extensive coma several thousand kilometers across.
How the observations were made
HiRIC is broadly comparable to NASA MRO’s HiRISE instrument but has slightly lower resolution. The observation required switching from routine imaging of Mars’ bright surface from low orbit to tracking a faint, fast‑moving object against a background of stars. At the time of observation 3I/ATLAS was estimated to be about 3.5 miles (5.6 km) across and traveling roughly 129,800 mph (58 km/s).
“Data acquired by a high‑resolution camera was received, processed and displayed by a ground‑based application system,” CNSA said in a Nov. 5 statement. “The images clearly show the comet’s distinctive features, consisting of a nucleus and a surrounding coma, with a diameter reaching several thousand kilometers.”
Why it matters
3I/ATLAS is only the third confirmed interstellar object to visit our solar system, after ‘Oumuamua (2017) and 2I/Borisov (2019). Because such visitors are so rare and pass quickly through the inner solar system, space agencies worldwide repurposed spacecraft — including orbiters and surface rovers at Mars — to gather observations from many vantage points.
Benefits for China’s space program
CNSA described the imaging campaign as an important extension of the Tianwen‑1 mission. Beyond the scientific value, the task provided engineers practical experience in tracking faint, distant targets and testing instrument and ground‑segment procedures — lessons that will inform future deep‑space missions such as Tianwen‑2, which launched in May and is en route to a near‑Earth asteroid sample return.
Background: Tianwen‑1 and Zhurong
Tianwen‑1 is China’s first planetary exploration mission. It launched in July 2020 and entered Mars orbit in February 2021. The mission’s Zhurong rover landed in Utopia Planitia in May 2021 and operated on the surface for about one Earth year.
In sum: The Tianwen‑1 images of 3I/ATLAS add a useful viewing angle to a rare, time‑sensitive international campaign to study an interstellar comet and demonstrate China’s growing capabilities in deep‑space observation and operations.