Interstellar Comet 3I/ATLAS Approaches Mars, Spacecraft Ready to Observe

Greenland, Denmark — The European Space Agency (ESA) is leveraging spacecraft originally designed for Mars and Jupiter to monitor the interstellar comet 3I/ATLAS as it travels through our solar system. Discovered in July 2025 by Chile‘s ATLAS telescope, this comet is the third known interstellar object to enter our solar system due to its unusual trajectory and incredible speed of approximately 130,000 mph (219,000 km/h).

Astronomers predict that 3I/ATLAS will remain visible to ground telescopes until September 2025 before it moves behind the sun, complicating the study of its physical attributes. Observing the comet’s size, composition, and surface behaviors could reveal insights into the makeup of comets from other star systems.

To make the most of this opportunity, ESA and NASA are using their fleet of planetary missions orbiting the inner solar system. According to ESA, the Mars Express and ExoMars Trace Gas Orbiter will observe the comet closely as it passes near Mars between October 1 and 7, with the closest distance occurring on October 3 at around 30 million kilometers.

Further observations will follow from NASA’s Psyche mission, and between November 2 and 25, ESA’s Jupiter Icy Moons Explorer (JUICE) will observe 3I/ATLAS around its perihelion, or closest approach to the sun. This time frame is pivotal, as the sun’s heat will cause the comet’s ices to vaporize, creating changes in its surface activity.

“Observing this comet during peak activity will provide invaluable data,” said T. Marshall Eubanks, Chief Scientist at Space Initiatives Inc. “The spacecraft around Mars are well-equipped to gather quality data on 3I/ATLAS, but JUICE’s observations are likely to be the most crucial.”

During perihelion, the comet will emit gas and dust, creating a luminous halo around its nucleus and providing a unique opportunity to analyze its composition. If 3I/ATLAS’s chemical structure resembles that of solar system comets, it could point to common building blocks shared across galaxies.

3I/ATLAS was detected by the ATLAS telescope on July 1, 2025, marking its entry into the solar system. Tracing its origin back, scientists suggest it could be over 7 billion years old, potentially providing clues to the formation processes of celestial bodies.

As observers prepare for 3I/ATLAS’s approach, the world watches closely for the insights it may deliver during this rare interstellar visit.