Within a billion years, NASA’s Voyager 1 probe will reach the opposite side of the Milky Way disk from the Sun. By the time it arrives, the Sun will have boiled all the oceans on Earth, making it habitable. As a result, NASA may not be around to celebrate this remarkable milestone in the journey of one of its most famous spacecraft.
Last month I asked my brilliant student at Harvard, Shokhruz Kacharov, where the Voyager 1 spacecraft will be in a billion years. Using a detailed model of the distribution of matter in the Milky Way galaxy, Shokhruz was able to plot Voyager’s future orbit relative to the Sun over billions of years. The results will be presented in a forthcoming peer-reviewed article.
All of this may sound academic and not grounded “down to earth” as the adults in the room often pretend. But the reason for my question was on Earth. I actually thought of this question because most stars formed billions of years before the sun. So if a Voyager-like rocket was used on exoplanets more than a billion years ago, then corresponding space probes could now reach the Solar System from anywhere in the Milky Way disk. We can observe these interstellar objects with our telescopes as they pass close to Earth.
In particular, pairing a ground-based telescope with the Webb Space Telescope a million miles away will allow us to pinpoint the trajectory of objects and detect any non-gravitational acceleration they display. It would also be extremely sensitive to detect trailing gases from either cometary evaporation of natural ice or engine exhaust. But even without surrounding gas, the Webb Telescope can measure the surface temperature and size of objects based on the infrared flux they emit. This would allow us to determine their reflection of sunlight in the Earth-Sun separation if they are much larger than Voyager.
However, on Voyager’s size scale, our telescopes do not reflect enough sunlight to detect these objects unless they come close to Earth. Even better, if they collided with Earth, they would turn out to be interstellar meteors of unusual strength and material composition. Our next expedition to the site of the interstellar meteor IM1, which collided with Earth on January 8, 2014 and showed unusual strength and material composition, aims to find large pieces of this object and infer its origin.
Shokhruz and I have calculated the galactic orbits of all 5 probes that NASA has launched into interstellar space so far, namely: Voyager 1, Voyager 2, Pioneer 10, Pioneer 11 and New Horizons. We also calculated the past trajectories of two interstellar meteors, IM1 and IM2, as well as the interstellar object `Oumuamua and the interstellar comet Borisov.
The basic question of whether any of the interstellar objects detected near Earth are artificial will be better answered as more are discovered. The most promising way to increase the current sample of interstellar objects is with the Rubin Observatory in Chile, which will survey the southern sky every 4 days within a year with a 3.2 billion pixel camera that just arrived at the observatory a week ago. With its unprecedented sensitivity, the Rubin Observatory can find an interstellar object every few months. My postdoc, Richard Cloete, and I are developing the software needed to analyze Rubin’s data. By tracking the orbits of interstellar objects and observing them with other telescopes, we hope to reveal their likely origins and the nature of the environment that gave birth to them.
For the same reasons that humans may not be on Earth when Voyager arrives on the far side of the Milky Way, the senders of any interstellar probes may not be nearby on their exoplanet due to the evolution of their parent star when we receive these packages. in our mailbox near Earth. Even if these technological objects ceased to function long ago, their existence would indicate that there were other intelligent inhabitants in the Milky Way. Their trash is our treasure. Learning about their state of mind from what they left behind is like studying ancient civilizations on Earth that no longer exist based on the relics we find at archaeological sites.
During a recent public appearance, I was asked what I envisioned for the future of humanity. I explained that humans arrogantly believe that they are important actors on the cosmic stage. But the truth is that even on Earth’s provincial scene, life has survived massive catastrophes long before humans came on the scene, including global warming 252 million years ago that wiped out 96% of all marine species.
This gives hope that, in the grand scheme of things, life on Earth will also survive human-induced ecological disasters. Another way to put it is that microbes are more resilient than humans. In a billion years, human existence may be just a small footnote in the cosmic ledger. To gain a more balanced perspective, we need to seek out other actors on the space stage and learn from them. And if none of them survived, we can study their history based on the artifacts they left behind.
We are in no position to claim a major role in the history of the universe. But the good news is that we can find out what happened on the space stage and find pleasure in the fact that our own Voyager will reach the other side of the Milky Way from the Sun in a billion years. Isn’t this performance breathtaking?
Yes, we are short-lived meter-scale creatures with great physical limitations, but we are so ambitious and fearless that we can send our message in a bottle to the other side of the Milky Way, 50 thousand light years away. a billion years.
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 former chair of the Department of Astronomy at Harvard University (2011 -2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chairman of the Council on Physics and Astronomy of the National Academies. He is the best-selling author of the book “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and co-author of the textbook “Life in the Cosmos”, both released in 2021. His new book, “Interstellar”, is released in 2021. August 2023.