A Benevolent Visitor or Space Poison?

As 3I/ATLAS is set to come close to Earth in just two weeks, Harvard professor Avi Loeb is pondering the nature of this interstellar visitor. Is it a friend or perhaps something more sinister? The answer may hinge on the chemicals it carries.

Loeb noted in a recent conversation that “there is significantly more methanol than hydrogen cyanide.” He elaborated, saying, “Methanol is crucial for life’s origins.”

On the flip side, he also pointed out that high levels of hydrogen cyanide can be toxic. This information comes in light of recent images taken by the European Space Agency’s Juice spacecraft, which depicts the comet with two tails and releasing substantial gas as it nears the sun.

In a post on Medium, researchers discussed how the chemical makeup of the comet’s gas plume reveals important insights about its character.

Loeb referenced findings from the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile, which recorded measurements of both methanol and hydrogen cyanide in ATLAS throughout the autumn.

This is significant since methanol is often described as “a building block of amino acids and sugars essential to life’s chemistry.” He explained that young stars typically contain a lot of methanol, which has been observed extensively over the past couple of decades.

Loeb recalled a past discovery from 2006, where a methanol cloud was found using the Merlin radio telescope near a young forming star. Similarly, in 2016, ALMA detected methanol in the disk around TW Hydrae, another young star.

Interestingly, ATLAS also showed traces of hydrogen sulfide—a substance that was infamously used as a chemical weapon during World War I. Loeb humorously remarked that on a blind date with an interstellar object, one should watch out for signs of whether it might have introduced life on Earth or, conversely, act more like a “serial killer” spreading poison.

Fortunately, he believes that ATLAS is likely “friendly,” as the ratio of methanol to hydrogen cyanide is quite high—one of the largest ratios noted in any observed comet.

Loeb suggests this celestial object might have contributed to life in other galaxies. “If the solar system lacked certain building blocks, visits from objects like 3I/ATLAS might have been the source,” he mentioned. He has theorized that Earth could have been “pollinated” by various interstellar gardeners over its 4.6 billion-year history, which seems plausible given our limited observation timeline.

Despite his theories regarding ATLAS’s potential origins, Loeb asserts that these findings don’t dismiss the idea of extraterrestrial sources. He pointed out that the chemical composition hints at possible fuels, noting, “There are multiple interpretations regarding how the fuels could produce methanol and other compounds.”

He also discussed his observations of the comet’s “complex jet structure,” which he speculated might indicate the presence of rocket thrusters. His anticipation is that upcoming data releases, including the full Juice data set due in February 2026, will enrich our understanding of ATLAS’s chemical profile.

In a further development, the James Webb Space Telescope is set to capture images of the comet this month, likely around its closest approach to Earth on December 19th.