Harvard Physicist Plans To 'Ride' 3I/ATLAS Comet To Send Time Capsules to Aliens

The mysterious interstellar comet 3I/ATLAS has been the focus of public speculation since its discovery on 1 July 2025. Now, a top Harvard physicist has proposed a bold new use for such visitors.

In a paper published on 21 December 2025, Harvard physicist Avi Loeb proposed using these rare space travellers as a way to send messages—or even 'time capsules'—from humanity out into the cosmos. His new theory suggests that these naturally occurring objects could help us share our story with potential extraterrestrial life far more efficiently than ever before.

A Quicker Route for Interstellar Time Capsules

Loeb's proposal centres on forsaking the 'traditional' mindset of building a faster spacecraft and instead focusing on pragmatic methods of interstellar outreach. He suggests a practical approach that utilises the natural high-speed trajectory of cosmic wanderers like 3I/ATLAS for a quicker time capsule.

The existing efforts to contact extraterrestrial life rely on NASA's Voyager 1 and 2 spacecrafts, which are currently making their way out of the solar system. Attached to these probes are the Voyager Golden Records, which serve as a time capsule of sounds, images, music, and messages from Earth. Loeb called this effort a 'message in a bottle' for aliens, but stressed that it is an unduly slow process.

'If we are impatient in establishing physical contact with extraterrestrials, we can attempt to do better in reaching our cosmic neighbours with technological artefacts,' he wrote.

Why 3I/ATLAS Decisively Outpaces Voyager

The primary benefit of using interstellar comets is the massive speed advantage they hold over human-made spacecraft. Voyager 1, launched on 5 September 1977, is travelling at a speed of 17 kilometres per second. At this rate, the probe will require another 28,000 years to reach the assumed limit of the solar system.

In contrast, interstellar objects like 3I/ATLAS are already moving significantly faster, travelling at a speed of 60 kilometres per second. This higher velocity dramatically shortens the time required to escape the solar system. By relying on such a natural messenger, the journey time is cut by more than two-thirds. This means that, by Loeb's calculation, an artefact riding an object like 3I/ATLAS will head into outer space in only 8,000 years.

His data provides a compelling case for choosing an interstellar object over a bespoke probe when measuring the speed of cosmic communication.

Accelerating Humanity's Relays to the Cosmos

Loeb concluded: 'Riding 3I/ATLAS offers the benefit of reaching interstellar space by the year ~10,000 CE instead of the year ~30,000 CE.'

This significant time difference illustrates why humanity should consider banking on the high-speed natural messengers. Experts could choose to attach a record, similar to the one carried by Voyager, on future interstellar visitors. Alternatively, he suggested that messages could be carved onto the surfaces of these asteroids using a high-power laser beam, sending a more permanent marker of human existence.

While he acknowledged the inherent uncertainty that no one can predict if these messages will ever be noticed, the potential benefits of such a discovery are profound.

Should extraterrestrial life possess the technological instruments required to read such a message, Dr Loeb said it would open 'a new discipline on university campuses labelled as "Interstellar Archaeology".'