The European Space Agency (ESA) announced that data collected by the ExoMars Trace Gas Orbiter (TGO) probe, in orbit around Mars, increased the accuracy of the trajectory of the interstellar comet 3I/ATLAS by ten times. The observations took place in the first week of October, when the comet passed close to the red planet. The combination of these records with information from ground-based telescopes made it possible to refine the mapping of the route through the Solar System.
The CaSSIS instrument, originally designed to image the Martian surface, was aimed into space to capture the comet against the starry background. ESA’s Near-Earth Object Coordination Center (NEOCC) coordinated the data processing.
- Previous accuracy: approximately 1,000 km margin of error
- Current accuracy: reduced to approximately 100 km
- Average distance to the comet during observation: millions of kilometers
Observations carried out on Mars
The ExoMars TGO probe recorded 3I/ATLAS in several passes during October. Scientists adjusted the instrument’s parameters to compensate for the object’s rapid movement.
The orbital position of the sonda offered a unique angle, different from observations made only from Earth. This complementary point of view reduced uncertainties in the calculated orbit.
Radio signals detected on Earth
The MeerKAT radio telescope, in South Africa, captured signals of hydroxyl molecules (OH) emitted by the comet on October 24. The detection occurred five days before perihelion, the moment of closest approach to the Sun.
The observed patterns are identical to those recorded in other comets in the Solar System. The presence of water vapor confirms the cometary nature of the object.
Activity recorded at perihelion
3I/ATLAS reached its closest point to the Sun on October 31. During this period, warming intensified the release of gas and dust.
The comet’s brightness exceeded initial predictions made after its discovery in July. Amateur and professional observers have reported naked-eye visibility in dark-sky locations.
Predicted upcoming observations
The JUICE mission, currently on its way to Jupiter, will keep the comet in view until November 25th. The probe will record the object shortly after perihelion, when the tail and coma should be more developed.
The data collected by JUICE will complement the information already obtained by ExoMars TGO. The combination will allow us to model the evolution of cometary activity in greater detail.
Characteristics of the interstellar object
3I/ATLAS is the third confirmed object of origin outside the Solar System, after 1I/ʻOumuamua and 2I/Borisov. Its hyperbolic speed indicates that it is not gravitationally bound to the Sun.
The current trajectory points to a definitive exit from the Solar System in the coming years.
