Riding 3I/ATLAS to the Stars
The Voyager Golden Records, containing a time capsule of sounds, images, music and messages from Earth, were attached to NASA’s Voyager 1 and 2 spacecraft which are currently traveling out of the solar system. These records serve as humanity’s message for any intelligent extraterrestrial life that might find them, essentially a “message in a bottle” sent out to interstellar space.
If we are impatient in establishing physical contact with extraterrestrials, we can attempt to do better in reaching our cosmic neighbors with technological artifacts.
Traditional thinking would argue that we must construct a faster spacecraft to overtake Voyager and be recognized earlier. Indeed, interstellar artifact collectors might discover our fastest technologies first if their shorter travel times compensate for their later launch dates.
Voyager 1 was launched on September 5, 1977; coincidentally, just a few weeks after the extraterrestrial Wow! Signal was detected. Voyager 1 is traveling out of the solar system at a speed of 17 kilometers per second. It is currently at a distance of about 170 times the Earth-Sun separation (AU). Interstellar space starts outward of the boundary of the Oort Cloud at about 100,000 AU, inside of which icy rocks are still bound by gravity to the Sun and show up near Earth as long-period comets. Voyager 1 will reach that boundary in about 28,000 years.
In contrast, the interstellar object 3I/ATLAS has an outward speed of 60 kilometers per second. It will return to interstellar space in about 8,000 years. Riding 3I/ATLAS offers the benefit of reaching interstellar space by the year ~10,000 CE instead of the year ~30,000 CE.
The discovery of interstellar objects over the past decade offers new opportunities for humanity to send time capsules to interstellar space.
One approach would be to design interceptor missions that would deposit analogs of the Voyager’s Golden Records on the surface of a large interstellar object like 3I/ATLAS, with the hope that these records will be recognized by interstellar archaeologists. Another approach is to use a high-power laser beam to engrave a message on the dry surface of an interstellar asteroid.
Will this effort be worthwhile if extraterrestrials will not notice our technological marks on interstellar objects? This question echoes the famous philosophical thought experiment: “If a tree falls in a forest and no one is around to hear it, does it make a sound?”
With the mainstream mindset of terrestrial astronomers, we would certainly miss any such markers. But there is also a practical limitation. Our largest telescopes both on Earth and in space do not have sufficient angular resolution to resolve a billboard sign with letters as big as Manhattan Island at a distance of order the Earth-Sun separation. However, if any extraterrestrial billboard with letters that big shows up at a distance smaller than 0.1 AU, it will open up a new discipline on university campuses labeled as “Interstellar archaeology”.
Recognizing technological imprints on asteroids or comets from interstellar space would provide the cosmic perspective that we desperately need in our daily routines. Terrestrial museums featuring replicas of these imprints will likely attract larger audiences than Science Fiction movies.
Of course, there could also be functional instead of artistic imprints of technology on the surfaces of interstellar asteroids. These would mark attempts of extraterrestrials to mine them for precious minerals or fuel (as discussed here).
Future interceptor missions, like ESA’s Comet Interceptor (as described here and here), could get close to interstellar objects and provide close-up photographs of them (as discussed here). The existence of artificial lights or infrared excess from the heat generated by a technological power source inside an interstellar asteroid or a comet, could also be identified in Webb space telescope spectroscopy from a large distance.
Here’s hoping that our travel agencies will realize that interstellar objects offer a fast ride out of the solar system. If offered the opportunity, I would have loved to hitchhike 3I/ATLAS and let it carry my remains into interstellar space.
How long will it take 3I/ATLAS or Voyager to reach the opposite side of the Milky-Way disk of stars? Of order one billion years.
Since most stars formed billions of years before the Sun, any civilization near them would have had plenty of time to reach our backyard. Their technological Golden Record or the remains of their most ambitious explorers might be buried in interstellar spacecraft even if those were propelled by a copy of our rocket technologies from the 1970s.
ABOUT THE AUTHOR
Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
