NASA and ESA Probes Capture Unique Data on Interstellar Comet 3I/ATLAS

Scientific analysis is currently underway following observations of the interstellar object 3I/ATLAS, the third confirmed interstellar visitor documented within our solar system since its discovery on July 1, 2025, by the NASA-funded ATLAS survey telescope in Río Hurtado, Chile. The object, also designated C/2025 N1 (ATLAS), is characterized by an orbital eccentricity of approximately 6.14, confirming its hyperbolic trajectory and origin from outside the solar system. The comet reached perihelion, its closest approach to the Sun, on October 30, 2025, passing inside the orbit of Mars at a distance of about 1.4 AU, or roughly 130 million miles.

During this peak activity phase, solar conjunction obscured 3I/ATLAS from Earth-based observatories. NASA's Europa Clipper spacecraft, launched in October 2024, pivoted its observational focus to the comet upon its emergence from behind the Sun in November 2025. The spacecraft successfully observed 3I/ATLAS on November 6, 2025, from a distance of 102 million miles, repurposing its Ultraviolet Spectrograph (UVS) instrument. Due to its sunward vantage point, the UVS captured a rare downstream view of both the dust and plasma tails, yielding spectral fingerprints that included detections of oxygen, hydrogen, and specific dust features. Dr. Kurt Retherford of SwRI noted these observations provided a nuanced perspective on the comet's outgassing mechanisms, vital for understanding the composition of such interstellar travelers.

Simultaneously, the European Space Agency’s (ESA) Jupiter Icy Moons Explorer (JUICE) spacecraft monitored 3I/ATLAS as part of its mission to study Jupiter and its icy moons. JUICE captured an image using its Navigation Camera (NavCam) on November 2, 2025, just before its own closest approach to the comet on November 4, which occurred at approximately 66 million kilometers. The JUICE mission, which launched in April 2023, is designed to investigate the potential habitability of the oceans beneath the icy crusts of Ganymede, Callisto, and Europa. Data acquisition from JUICE’s five primary science instruments is scheduled for transmission in February 2026, as the spacecraft utilized its main high-gain antenna as a protective heat shield during trajectory maneuvers.

The convergence of these two distinct observational platforms offers a significant scientific advantage. The Europa Clipper’s unique sunward perspective, combined with JUICE’s more conventional viewing angle relative to the comet, will enable researchers to synthesize a comprehensive, three-dimensional model detailing the comet's physical composition and tail structure. This level of detail is critical, as interstellar objects like 3I/ATLAS are pristine samples from other stellar systems, preserving clues about the formation of distant protoplanetary disks. The object, which reached a speed of about 153,000 miles per hour at perihelion, is currently on an outbound trajectory, scheduled to pass near Jupiter in March 2026 before exiting the solar system.