Interstellar Diary

Avi Loeb
6 min readMay 10, 2023


The book “Les voyages de Marco Polo (The travels of Marco Polo)”, written in 1300 by Rustichello da Pisa from stories told by the Italian explorer Marco Polo, includes an account of Polo’s adventures in Central Asia and the Far East during the last quarter of the 13th century. If the internet had existed 750 years ago, Polo would have shared his experiences directly on social media without a mediator.

In summer 2023, I will be leading a Galileo Project team on an expedition to the Pacific Ocean to retrieve fragments of the first interstellar meteor, IM1, that I discovered with Amir Siraj. The material strength of this meteor was higher than all other 272 space rocks in the CNEOS catalog of NASA. We hope to analyze its composition and infer whether it originated from an exotic astrophysical source or perhaps manufactured by an extraterrestrial technological civilization. We have produced magnetic sleds and sluicing devices to retrieve the meteor’s fragments, contracted a suitable boat, and arranged for the best instruments and professionals at Harvard University to analyze the retrieved sample upon return, following a preliminary X-ray fluorescence spectroscopy on the boat.

Like Polo, I have no account on social media. But I do write research updates in essays and plan to post an expedition diary detailing our daily experiences during the upcoming ocean adventure. Polo’s account was regarded as a “new description of the world.” Here’s hoping that the forthcoming Galileo Project expedition will be regarded as a “new description of other worlds.”

Unlike Polo, we focus our attention on one site on Earth, where the meteor’s fireball was observed. However, the relics we hope to find travelled for millions to billions of years through interstellar space. IM1 was the first interstellar object detected by humans on January 8, 2014. It was half a meter in size and the end of its journey was marked by three flares of fireworks containing a few percent of the energy of the Hiroshima atomic bomb, as a result of its friction with the lower atmosphere of Earth.

The three flares likely represent the breakup of IM1 into three comparable-size pieces. If any large piece of it survived, it must have been manufactured technologically. Otherwise, I calculated in a recent paper with Amory Tillinghast-Raby and Amir Siraj that even the toughest iron meteorite would have disintegrated into tiny, millimeter-size spherules that rained down on the ocean following the explosion.

There are many challenges. The ocean is a mile deep at the meteor explosion site, and the task of finding tiny particles on the ocean floor is immensely challenging. Nevertheless, we must keep a beginner’s mind and search agnostically, because without searching — we will definitely not find anything. To paraphrase on John F. Kennedy’s speech at Rice University which took place during my birth year of 1962, `We choose to go to the Pacific Ocean this summer and do the other things, not because they are easy, but because they are hard.’

I told Rob McCallum, our accomplished expedition coordinator, that I will be happy to sleep near the machine room since I prefer to stay half awake and be ready any time to examine the material we bring up from the ocean floor. Like any other scientific project, this will be a team effort and I plan to host a team dinner at my home on the day before departure.

In an online meeting with the expedition funder, Charles Hoskinson, we discussed our final organizational plans with him on the boat. I committed to include Charles in the scientific papers that will result from the expedition, and showed him a hardcopy of the galley proofs for my forthcoming book “Interstellar” about the extraordinary implications of a successful mission. At the end of our discussion, Charles mentioned a conversation about filming the expedition with the Canadian film producer, Odessa Rae, known for producing the documentary Navalny, which won the Best Documentary Feature at the 95th Academy Awards. As I was explaining that we already have an exceptional filming crew, members of that crew happened to knock on the door of my home for a coordination meeting. They overheard the exchange, and whispered: “Back off Odessa.” As it turns out, they are close friends with Odessa. They instantly messaged her that they are already busy with the task.

The expedition outcome offers a rich backdrop for a science fiction story. While I love doing science and I enjoy reading fiction, I prefer not to imagine what we might find in the Pacific Ocean because reality could be grander than our imagination. For example, IM1 could have included a technological nugget that was protected by design from the heat released during its entry into the Earth’s atmosphere. In that case, we could recover a functioning device. To find larger pieces, we have cameras on our sleds and plan to analyze their footage along with the material they return to the boat. But even without designed protection, the fragment-size-distribution calculation I performed with Amory and Amir, implies the possible existence of inch-size fragments in case IM1 was made of stainless steel.

The worst-case scenario is that we will not find anything. Nevertheless, life is fulfilling when you know that you tried. We are prisoners of Earth’s gravity, and so any interstellar visitor can tell us a story of what lies beyond our limited experience in the solar system, all the way out there within the vastness of cosmic space and time.

We already recognize that 95% of the mass budget of the cosmos is dominated by the substances of dark energy and dark matter, which were never witnessed in the solar system. That our daily experiences are shaped by 5% of the content of the Universe should give us a pause and convince us to be humble in welcoming the unexpected.

An interstellar visitor will bring a metaphorical diary of its journey’s history, far more expansive than the terrestrial adventures of Marco Polo. There might be a richness to the known 3+1 dimensions that is far more spectacular than the imagined landscape in the extra-dimensions of string theory.

Whatever we find will be recorded in my personal diary, to be shared through the boat’s Wi Fi connection on this outlet with no subscription fees. Human technology advanced a great deal over the past millennium, but technological civilizations that lived and died around older stars, could have had a head start of billions of years relative to us. We might have a lot to catch up with. Let us start in the Pacific Ocean.


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 chairs the advisory board for the Breakthrough Starshot project, and 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. His new book, titled “Interstellar”, is scheduled for publication in August 2023.



Avi Loeb

Avi Loeb is the Baird Professor of Science and Institute director at Harvard University and the bestselling author of “Extraterrestrial” and "Interstellar".