Interstellar comet 3I/Atlas from another system slightly threatens Nasa probe to Jupiter
The Europa Clipper probe, launched by Nasa toward Jupiter’s moon Europa, crosses the ion tail of comet 3I/Atlas between October 30 and November 6.
The object, the third confirmed interstellar in the Solar System, originates outside the Sun’s influence and poses minimal risk to the spacecraft.
Key facts:
- Discovered on July 1, 2025, by the Atlas telescope in Chile.
- Perihelion on October 29 at 1.4 astronomical units from the Sun.
- Composition rich in carbon dioxide in the coma.
Trajectory confirms external origin
European researchers used the Tailcatcher model to simulate the encounter. The tool calculates particle flow under solar wind action between Sun, comet, and probe.
The alignment occurs about 8 million kilometers from the comet’s nucleus.
Unique composition of 3I/Atlas
Carbon dioxide dominates
James Webb Space Telescope observations reveal unusual CO2 proportion in the gas and dust cloud.
This dominance differs from local comets.
The coma shows a CO2/H2O ratio of up to 8:1.
Nucleus and activity
The nucleus diameter ranges between 440 meters and 5.6 kilometers.
Activity detected since May 2025 at 6.4 astronomical units from the Sun.
Space telescope observations
Hubble and James Webb telescopes recorded diffuse coma and weak tail in July.
The Nordic Optical Telescope confirmed activity on July 2.
Instruments involved:
- Webb’s NIRSpec for infrared spectrum.
- Hubble cameras for coma structure.
- Gemini South for water ice detection.
Data indicate water production of 40 kg per second.
Encounter with Europa Clipper
The probe has a magnetometer and plasma instrument suitable for measurements.
Alignment steps:
- Comet reaches perihelion on October 29.
- Ion tail expands with peak activity.
- Ion flow reaches the probe’s position.
- Detection of magnetic field changes.
Direct damage risk is low, according to Nasa.
Hera also on the path
The European Hera mission, heading to asteroid Didymos, crosses the tail between October 25 and November 1.
Hera lacks plasma analysis instruments.
Other missions monitor
Juice observes in November
Esa’s Juice probe uses cameras and spectrometers for post-perihelion view.
Coordination with Europa Clipper in ultraviolet.
Mars rovers
Perseverance and Curiosity captured the comet as a bright point.
Scientific potential of the crossing
Direct plasma measurements provide data on stellar system formation.
Charged particles reveal chemistry from another stellar environment.
3I/Atlas preserves material from billions of years ago.
