ESA’s Jupiter Icy Moons Explorer, or Juice, has recently captured striking new observations of Comet 3I/ATLAS. In November 2025, the spacecraft employed five of its scientific instruments to study the comet, collecting crucial information about its activity, structure, and composition. These measurements are helping scientists understand the behaviour and characteristics of this interstellar visitor. Alongside these instruments, Juice’s Navigation Camera, NavCam, provided an initial visual glimpse of the comet, revealing its shape and surface features. This early imagery gives researchers a preliminary view and helps guide expectations for the more detailed data collected by the other instruments. Juice’s observations mark an exciting step in studying distant comets.
Comet 3I/ATLAS captured in stunning detail by Juice’s navigation camera
Juice was originally designed to explore Jupiter’s icy moons, with its NavCam intended primarily for navigation rather than high-resolution scientific imaging. However, the spacecraft turned its attention to Comet 3I/ATLAS in November 2025, capturing images and preliminary data. The observation was made in the days leading up to Juice’s closest approach to the comet, which occurred on 4 November at a distance of approximately 66 million kilometres.Although the detailed measurements from Juice’s scientific instruments will not reach Earth until February 2026, the mission team was able to extract a quarter of a single NavCam image to provide an early look at the comet. This preview revealed the comet clearly, surrounded by signs of activity, much to the surprise and excitement of the scientists. The NavCam image shows the comet with a glowing halo of gas, known as its coma, which is a key indicator of cometary activity. There is also evidence of two distinct tails. The plasma tail, composed of electrically charged gas, extends towards the top of the frame, while a fainter dust tail, made of tiny solid particles, stretches to the lower left. These features are typical of comets as they heat up when approaching the Sun, releasing gas and dust into space.This observation occurred shortly after the comet’s closest approach to the Sun, meaning 3I/ATLAS was in a highly active state. Scientists anticipate that the data from Juice’s scientific instruments will reveal these processes in even greater detail, including the composition and behaviour of the cometary material.
Juice’s five scientific instruments and data transmission challenges
Juice is equipped with five instruments that were activated to study 3I/ATLAS:
- JANUS: The high-resolution optical camera, capable of capturing detailed images of the comet’s surface and tail structures.
- MAJIS: A spectrometer that analyses the light emitted and reflected by the comet, revealing its chemical composition.
- UVS: An ultraviolet spectrometer that helps detect specific gases in the coma.
- SWI: The Sub-millimetre Wave Instrument, which provides information on the comet’s temperature and molecular composition.
- PEP: The Particle Environment Package, which measures charged particles around the comet.
These instruments will provide a comprehensive dataset, including images, spectrometry readings, and particle analysis, giving scientists new insight into how Comet 3I/ATLAS behaves as it travels through the inner Solar System.Due to Juice’s current orientation, its main high-gain antenna is being used as a heat shield to protect it from the Sun. As a result, the spacecraft must rely on its smaller medium-gain antenna to transmit data back to Earth. This limitation significantly reduces the transmission rate, which is why the full dataset from the scientific instruments will only arrive on 18 and 20 February 2026.
Early NavCam observations reveal comet activity and Juice’s scientific versatility
Despite the limited preview from the NavCam image, scientists are already excited by the visible signs of activity in Comet 3I/ATLAS. The presence of both plasma and dust tails, along with the bright coma, indicates a dynamically active comet. When the full scientific data arrives, researchers expect to gain unprecedented detail about the comet’s composition, outgassing behaviour, and interaction with the solar wind.Juice’s observations of Comet 3I/ATLAS demonstrate the spacecraft’s versatility, showing that even instruments designed for navigation can provide valuable scientific insights. These early findings promise to deepen our understanding of comets and the complex processes that shape their behaviour.Also Read | ESA discovers butterfly-shaped crater on Mars revealing impact, volcanic activity, and possible water
