A Harvest of 92 New Spherules in One Day!

Avi Loeb
6 min readJul 15, 2023


Diary of an Interstellar Voyage, Report 38

(July 14, 2023)

The first-day harvest of my summer intern student at Harvard, Sophie Bergstrom, included ten new spherules, plus one held by tweezers, from the first recognized interstellar meteor, IM1.

Upon our return to the US from the deck of the ship Silver Star, we visited Ryan Weed’s laboratory at UC Berkeley and left a few spherules from the Pacific Ocean site of the first recognized interstellar meteor, IM1 , for further study by members of his research team. During that day, exactly two weeks ago, their scanning electron microscope revealed a nested structure of spheres within spheres from the outer diameter of a millimeter down to the length-scale of hundreds of atoms. The plume of ions ablated by a laser — beamed on a spherule, was transmitted through a mass spectrometer and revealed a rich wealth of isotopes from Lithium-6 to Uranium-238, which we are still interpreting.

The bulk of the materials arrived from UC Berkeley to my doorstep over the past week. I immediately shipped some vials to Roald Tagle at the Bruker Corporation in Germany, which he just received over the past day. Also, over the past day I arranged for my summer intern student at Harvard, Sophie Bergstrom, the opportunity to sift the remaining materials for any missed spherules, using a microscope and tweezers.

Within one day, I received three amazing reports. First, Sophie found her first spherule candidate and emailed me a photo of it to inquire whether it is real. From our experience on Silver Star, I told her that biological spheres can be crushed by pressing on them with tweezers and she indeed made sure that the metallic marble she discovered cannot be crushed. Half a day later, I received an email from Roald who reported that he discovered 81 new spherules in all the materials he received. A few hours later, Sophie reported 10 more spherules. Altogether, the harvest on this first search day was 92 new spherules, nearly double the total number identified on Silver Star.

A close-up photo of one out of the 81 new spherules that were discovered today by Roald Tagle at the Bruker Corporation in Berlin, Germany.

During the analysis at UC Berkeley, one of the first 50 spherules from Silver Star was destroyed. But with so many newly delivered spherules, we should not mourn the loss of one.

Altogether, we now have an abundance of (92+49)=141 spherules from both the meteor path and control regions, with more to be found in the next few days. We will be analyzing their composition in terms of elements and radioactive isotopes in the coming weeks, and compare the results to solar system spherules.

Based on a research agreement signed before the expedition with the University of Technology at Papua New Guinea, the head of the Mining Engineering department there, Dr. Jim Lem, is scheduled to visit Harvard in the near future and participate in our analysis. We plan to summarize our results in a scientific paper to be submitted for publication in a peer-reviewed journal.

When studying the composition of spherules, we will examine the possibility of a so-called “New Horizons meteor”, in which the composition of the molten droplets would reveal a technological origin of space trash akin to our New Horizons spacecraft colliding with an Earth-like exoplanet in billions of years and burning up as a meteor in its atmosphere. Imagine depositing IM1’s fireball energy per unit mass of a few percent of the Hiroshima atomic explosion into 500 kilograms of matter containing computer screens and semiconductors. In that case, the molten droplets on the ocean floor would likely be enriched with rare elements, well beyond their abundance in natural rocks.

The amazing harvest of 92 new metallic marbles made my day. This was an uplifting ending to two exhausting weeks following our return, during which I averaged ten interviews per day.

Despite the stress, I maintained my strength thanks to unexpected artistic gifts. To illustrate their uplifting character, here are a few examples that arrived just this week. First, a sculpturer wrote:

“Dear Professor Loeb,

I am a sculpturer living in Spain with a scientific background (Cambridge University, Harvard University).

I have long admired your publications and independent thinking, and value your work immensely. You have been a huge inspiration for me, and I am sure that you have an opportunity to answer the most important questions facing humanity ever.

I have some of my work in the process of being installed in various locations, including … for a Nobel laureate…

In recognition of my personal admiration and gratitude for how you have influenced my own thinking, I would like to dedicate a small sculpture in honor of your career as a gift…

I really hope that you like this idea. It has been on my mind for a couple of years…

My kindest regards …”

Second, a song writer who won three Oscars, two Grammys, two Golden Globes and four Emmys, wrote:

“Dear Avi,

…I do not have a scientific bent at all, but I’m thrilled to get the chance to write a song … about you and the amazing work you do in astrophysics. I will try and make it a wonderful marriage between art and science.

In the meantime, take care. Stay well.

Best regards, …”

Third, a playwright from Los Angeles sent me a finished play in celebration of my scientific career, along with the note:

“Dear Avi:

It is with such joy that I send the first complete draft of our play….

Avi: It exists.


Fourth, a podcaster gifted me with a montage of photos from the interstellar expedition to the tunes of “Silver Star”. To view it, click here.

Today, ten out of the ten interviews I had, ended independently with the same words: “Thank you for your inspiring research and for delivering a honest, curious and uplifting message to all of us. Please stay well and keep doing what you are doing. We root for the success of your leadership and optimistic vision for the future!”

Within a month, I am scheduled to publish my next book, Interstellar, which summarizes my vision for humanity in interstellar space.

We tend to focus on affairs at our home, the Earth. But we better visit our back yard, the solar system, and check whether we only find familiar rocks there. Every now and then we might encounter odd objects from the street, such as a tennis ball thrown by a neighbor. These odd interstellar objects, like IM1 or `Oumuamua, would not resemble familiar asteroids or comets.

As long as we are willing to acquire new knowledge, we could use these oddities as an opportunity to learn about our neighbors. The awe associated with witnessing advanced interstellar gadgets, could promote new technologies on Earth as well as a new sense of humility and respect, akin to spiritual learnings.

But all of this would be possible as long as scientists are willing to seek evidence and admit its implications, free of the chains of groupthink and professional ego. Insisting that any object in the sky must be a stony meteorite — as advocated for IM1 by meteor experts last week, would leave us in the scientific stone age. On the other hand, accepting the assertion of the US Space Command that IM1 is interstellar at the 99.999% confidence, would make us sleep better at night — knowing that the US is well protected from ballistic missiles by the same sensors that measured IM1’s speed.

Allowing for interstellar partners starts with the humility of treating exquisite data with respect.


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".