Recent advancements in tracking the trajectory of comet 3I/ATLAS, the third known interstellar object, have been made by the European Space Agency (ESA). Discovered on July 1, 2025, this comet posed no threat to Earth but became a focal point for astronomers studying trajectory prediction methods.
ESA’s Innovative Approach
ESA enhanced the comet’s predicted location by tenfold using data from the ExoMars Trace Gas Orbiter (TGO). This spacecraft, positioned in orbit around Mars, provided a unique vantage point to observe 3I/ATLAS.
Initially, from its discovery until September, astronomers relied on Earth-based telescopes to speculate about the comet’s position. However, between October 1 and 7, 2025, TGO captured images of the comet when it came within approximately 29 million kilometers of Mars.
Significant Observations
- On October 3, 2025, 3I/ATLAS was closest to Mars.
- Observations from TGO were about ten times closer than Earth-based methods.
- High-speed travel: The comet moves at speeds approaching 250,000 km/h.
This new perspective allowed scientists to refine the comet’s trajectory with remarkable precision. While initial expectations were modest, the results significantly surpassed them, improving prediction accuracy and decreasing uncertainty about the object’s location.
Technical Challenges and Collaboration
Utilizing the Mars orbiter’s capabilities posed challenges, as the CaSSIS instrument was primarily designed to observe the Martian surface. Astronomers had to adjust their methods to successfully capture detailed images of 3I/ATLAS against the Martian sky.
Coordination between different teams at ESA was crucial. Experts in flight dynamics, science, and instruments collaborated effectively to address issues that could affect data accuracy. This marks a historic first where measurements from a spacecraft orbiting another planet were submitted to the Minor Planet Center (MPC) database.
Implications for Planetary Defense
Although 3I/ATLAS is not a threat, the exercise has broader implications for planetary defense strategies. ESA regularly monitors near-Earth objects, and this incident exemplified the importance of triangulating data from both Earth and space.
The success of this mission emphasizes the need for continued development of methodologies to track celestial objects. ESA’s Mars and Jupiter missions, including the Jupiter Icy Moons Explorer (Juice), will continue monitoring 3I/ATLAS. Expect updates on its findings in February 2026.
Future Missions
Looking ahead, ESA plans the Neomir mission, designed to detect near-Earth objects obscured by the Sun. This mission aims to provide warnings of potential impacts at least three weeks in advance.
ESA is also preparing the Comet Interceptor mission to learn more about comets, including the possibility of studying another interstellar object. These missions highlight humanity’s continued drive to explore and understand our galaxy.
