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Interstellar Visitor 3I/ATLAS Shows Water and CO2 Activity as Mars Orbiters Snag Difficult Views

Orbital solutions place it far from Earth, with more coordinated analyses due before its late-October perihelion.

Overview

  • ESA’s ExoMars Trace Gas Orbiter captured 3I/ATLAS as a faint diffuse point near Mars, and Mars Express teams are stacking short exposures and assessing spectral measurements to firm up the detection.
  • NASA’s Mars Reconnaissance Orbiter and the Perseverance rover obtained detections or raw frames, though public releases have been limited during the recent U.S. government shutdown.
  • Spectroscopy from space-based observatories, including JWST, indicates a coma dominated by carbon dioxide with additional volatiles such as water and carbon monoxide.
  • NASA’s Swift observatory detected OH that signals early water release at large heliocentric distance, with new analysis estimating outgassing near 40 kilograms per second well before close solar approach.
  • NASA affirms no impact risk to Earth, with closest approach around 1.6–1.8 astronomical units, as the object nears perihelion on October 29–30 before receding from the inner solar system.