As we await the World Cup final on July 19, 2026, it is timely to recall that over the past decade, astronomers discovered three interstellar objects larger than a soccer field as they traversed the inner Solar system: 1I/`Oumuamua, 2I/Borisov and 3I/ATLAS.
These are three missed opportunities.
If our technological civilization had been more ambitious, it would have planted a technological gadget inside these visitors. Interstellar objects like 3I/ATLAS travel a few times faster than all five human-made probes launched to interstellar space so far.
Hitchhiking interstellar objects which pass near Earth over the next billion years before the Sun will boil off all the oceans on Earth, could fill the Milky Way with hundreds of millions ambassadors from Earth. These technological messengers would masquerade as natural objects to outside observers, allowing them to penetrate even the most guarded territories of alien civilizations like Trojan Horses.
The gadgets can be activated once the background illumination from a nearby star exceeds the habitability threshold of order a kilowatt per square meters. As soon as their gravitational acceleration peaks at closest approach to the illuminating star, they would be programmed to depart from their interstellar hosts in a direction perpendicular to that acceleration. An Oberth maneuver in the opposite direction relative to their carrier’s velocity would be the most efficient way for using their engine to slow down to the desired bound orbit around the star. A follow-up search for nearby planets with suitable liquids and solids for seeding biological life could accomplish directed panspermia.
My calculations indicate that a few hundred of such probes could reach the habitable zone around Sun-like stars within a billion years. If a percent of all Sun-like stars in the Milky-Way leads to a civilization that engages in such an activity, then the habitable zones around all Milky-Way stars will be visited by technological hitchhikers on interstellar objects within just a tenth of the age of the galaxy.
However, even one ambitious civilization can accomplish much more by producing self-replicating spacecraft which land on planets and reproduce themselves out of raw materials, as envisioned by John von Neumann around 1950 and Ronald Bracewell a decade later here.
To read more, click here.