On its way to Jupiter, ESA’s JUICE spacecraft observed the rare interstellar comet, 3I/ATLAS, gathering crucial data from an object originating beyond our solar system.

This stunning image of 3I/ATLAS was taken by the Navigation Camera (NavCam) aboard JUICE in November 2025. Image credit: ESA/Juice/NavCam.

3I/ATLAS, discovered on July 1, 2025, by the NASA-funded ATLAS survey telescope in Rio Hurtado, Chile, is an extraordinary interstellar comet. Also referred to as C/2025 N1 (ATLAS), this comet entered our solar system from the direction of the constellation Sagittarius.

The comet features the most dynamically extreme orbit ever recorded in the solar system, showcasing its interstellar origins and remarkable speed.

On October 30, 2025, 3I/ATLAS reached its closest perihelion to the Sun, coming within 1.4 AU (astronomical units) of Earth, just inside Mars’ orbit.

“From the moment of its discovery, we understood that the unique shape of its orbit would allow JUICE to observe it from a different perspective than Earth,” explained Dr. Marco Fenucci, a mathematician and near-Earth object dynamist at ESA’s Near-Earth Object Coordination Center.

Predictions indicated that JUICE would be the closest spacecraft to 3I/ATLAS in November 2025, shortly after it reached perihelion.

“Preparing for payload pointing campaigns and flybys generally requires about nine months,” noted Angela Dietz, JUICE spacecraft operations manager. “When ATLAS appeared, we recognized that time was limited.”

JUICE commenced 3I/ATLAS observations on November 2, 2025, continuing until November 25. The closest approach occurred on November 4, at approximately 0.4 astronomical units.

Utilizing five instruments—JANUS, MAJIS, UVS, SWI, and PEP—the spacecraft conducted extensive measurements of the interstellar visitor.

Due to thermal limitations, observations were restricted to six 45-minute slots and one final 4-hour slot.

These sessions yielded 126 scientific files, totaling 11.18 gigabits of invaluable data.

However, scientists must wait for the results, as high bitrate downlinks are feasible only after JUICE enters the cold cruise phase in mid-January 2026.

The eagerly awaited data downlink happened over two 11-hour passes on February 17 and 20, 2026, using ESTRACK’s New Norcia and Malargüe deep space antennas.

“What we do is a collaborative effort, and the ability to optimize this campaign in such a short timeframe is something we take pride in,” stated Dietz.

“Jupiter’s icy moons are frequently visited, with flybys occurring just weeks apart.”

“The successful 3I/ATLAS campaign enhances our confidence that JUICE can efficiently meet scientific objectives on short notice and effectively manage complex operations within tight schedules,” commented Federico Giannetto, JUICE spacecraft operations engineer.