Black Powder in the Debris Field of the First Recognized Interstellar Meteor, IM1

Avi Loeb
5 min readJun 19


Diary of an Interstellar Voyage: Part 16 (June 20, 2023)

Video footage revealed a rock that the expedition’s magnetic sled bumped into during Run 4 in IM1’s debris field.

As I was jogging on the deck of Silver Star, the workout app on my electronic watch indicated a frustratingly slow paste of motion compared to the one that I am used to. By the end of the run I realized that I must have been facing the opposite direction relative to the motion of the ship. The motion of the platform under my feet might have slowed down my inferred speed relative to the Earth’s frame of reference as calibrated by GPS satellites. The lesson to be learned from this experience is that everything is relative. As Oscar Wilde noted: “The only people who appear normal to me are those who I do not know very well.”

Similarly, the definition of an anomaly in physics relies on a good understanding of the background. This applies to the direct search for dark matter particles in laboratory detectors, as well as to Galileo Project expeditions in search of technological relics from extraterrestrial civilizations.

In Run 8, the sled’s magnets were saturated with the background of volcanic black powder. The interesting question is whether this magnetic background entrains tiny fragments of IM1. We will explore this possibility with further analysis.

Run 8 of the magnetic sled through the likely crash site of the first recognized interstellar meteor, IM1, about 84 kilometers off the coast of Manus Island in Papua New Guinea, yielded a large harvest of volcanic black powder, which we plan to run through our gamma-ray spectrometer in the coming days in order to characterize its radioactive constituents.

This black powder is dominated by a large background of volcanic ash but may contain dust from the exterior of IM1. The video footage from the sled’s camera showed clear evidence for volcanic rocks as well as hydrothermal vents that were the source of life on Earth. Despite the darkness of the ocean floor at a depth of 2 kilometers, the “nightlife” appears to be thriving there as much as in Las Vegas.

Biological background: a sled-dragged boulder hits a stationary rock on the ocean floor with a sea-fan on it.

The producer of the expedition’s documentary, Dan Levine, who also produced my favorite science-fiction film `Arrival’, emailed me to say: “I wonder as you are gazing up at the Milky Way, who is gazing back at you…”, to which I replied: “any documentaries they are making might not be as good as yours. Your film has a good chance of winning the Galactic competition.”

We realize that IM1’s debris had rested on the ocean floor for nearly a decade and could have been coated by biological or geological processes. For example, we suspect that the silica detected on the surface of the steel shards we recovered from IM1’s debris field was probably background contamination. To remove it, we polished one of the gray shards from Runs 6 & 7 and noticed a significant reduction in its silicon content, making a high-confidence identification of its composition as similar to Series 1100 Low Alloy Steel with a material yield strength in a range above 165 MPa, surprisingly close to the ram-pressure at which IM1 disintegrated.

Once we are able to trace IM1’s path based on criss-crossing its debris field, we could potentially search for evidence of any large body at the end of IM1’s path as it impacted the ocean floor. If IM1 were of technological origin, we can then study the technologies embedded in its relic.

An image of corroded iron fragments at the bottom of the ocean, showing a variety of sizes. Some of the shards could potentially be of extraterrestrial origin. Analysis of the abundance of radioactive isotopes can determine whether the shards originated from Earth or from a long interstellar journey of IM1, lasting millions to billions of years, during which isotopes with a short half-life would be depleted.

We plan to store all the retrieved materials at the Harvard College Observatory upon our return, and then analyze them with the most sensitive instruments available worldwide. This would allow us to reach detection sensitivities for radioactive isotopes that are a hundred times better than that attainable on Silver Star. The improvement in the signal-to-noise ratio of the gamma-ray spectral lines from our sample improves in proportion to the square root of the integration time, so there is little benefit from integrating each measurement on the ship for more than a single day.

We already know that the Uranium content of our steel shards is not orders of magnitude larger than expected on Earth, but we cannot reach the sensitivity needed to assess if some of it was depleted during an interstellar journey. With our laboratory tools back home, we will be able to conclude with confidence whether the sample of steel shards is of terrestrial or interstellar origin, irrespective of the details associated with human-made trash in the Pacific Ocean near Papua New Guinea. The beauty of science is that it can dissociate its conclusions from details associated with the behavior of humans. I told the documentary director, Jason Kohn, that I hate crowds of people because by listening to all they say — I end up wasting most of my time on noise rather than on signal.

Here’s hoping for a large extraterrestrial signal relative to our terrestrial noise on the ocean floor at IM1’s crash site.


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".