On June 14–28, 2023, I led an expedition to the Pacific Ocean to retrieve remnants of the meteor IM1, which was listed by NASA in the CNEOS catalog of fireballs and formally confirmed to be interstellar in origin by the U.S. Space Command in a formal letter to NASA, available here. About 850 molten droplets, or spherules, were collected and brought to analysis in the state-of-the-art geochemistry laboratory of Professor Stein Jacobsen at Harvard University. The expedition will be featured in a Netflix documentary and a new book to appear in 2026.
About a tenth of the spherules retrieved from the expedition showed a highly enriched composition, with elements like beryllium (Be), lanthanum (La) and uranium (U) having an abundance of up to a thousand times the solar elemental composition. These unique fragments were classified as “BeLaU”-spherules, and their complete elemental pattern did not match that of any well-studied solar system material.
Skeptics speculated that the BeLaU signature might represent either human-made coal ash or a tektite strewn field. Tektites are glassy rocks formed from terrestrial material melted and ejected by the hypervelocity impact of a large meteorite.
Last year, our research team conducted a detailed analysis that demonstrated beyond any reasonable doubt that the BeLaU composition is different from that of coal ash (see Figure 1c in our published paper here).
This week, the brilliant scientist Dr. Eugenia Hyung from Jacobsen’s laboratory, led a paper co-authored by four students, Stein and myself (accessible here), which reports precise elemental data for Australasian tektites to test the second speculation raised by the skeptics. In short, our finding is that the Australasian tektites closely resemble the elemental abundance pattern of the upper continental crust of Earth for all the elements analyzed and are very different from the BeLaU composition.
Let us start with some background information. The entry of the interstellar meteor IM1 into the Earth’s atmosphere on January 8, 2024 resulted in three atmospheric detonations, which were detected by U.S. government satellite sensors 84 km north of Manus Island. Our analysis of the event (published here) suggested an object of interstellar origin due to its arrival velocity of more than 45 kilometers per second, inspiring an ocean expedition to retrieve remnants of the object as discussed in a peer-reviewed paper here. Among the retrieved fragments were 850 spherules that were 0.05–1.3 mm in diameter. The majority (~80%) of these fragments consisted of cosmic spherules, categorized into “S-type,” “I-type” and “G-type” spherules of undifferentiated composition and familiar chondritic origins. A fraction of the materials that did not fit into the three archetypal categories were further classified as “D-type” spherules, named after their highly differentiated compositions in comparison to chondrites, characterized by their low magnesium to iron ratio. About half of the D-type particles was further sub-categorized and named “BeLaU,” after their unusual composition — exhibiting in particularly high abundances in elements such as Be, La, and U compared to known materials. The “BeLaU” composition is of unknown origin, potentially from beyond the solar system (as published after peer-review in a paper accessible here).
A few skeptical scientists who had no access to the materials speculated that the BeLaU spherules originated from an Australasian tektite strewn field and microtektites of lateritic soil. Tektites are melted droplets, solidified from melt or condensed from vapor due to meteoritic impacts and are characterized as glassy silicate objects that are round, oblong, flanged-button, dumbbell, or tear-dropped in shape, and black in color. Tektites have in general been established to originate from impacts onto areas with close to average upper continental crust in composition. Only minor or no traces of the impactor are found in the tektites. Tektites that are less than 1 millimeter in diameter are referred to as “microtektites” or “microkrystites” depending on the absence or presence of microlites, respectively. Among the various types of tektites, Australasian tektites and microtektites were proposed as candidate for the BeLaU composition due to the proximity of the expedition site to the strewn field identified for the Australasian tektites. This field covers parts of China, Indonesia, the Pacific Ocean, the Indian Ocean, Australia, and Antarctica. The IM1 fireball site is close to the putative impact site for the Australasian tektites, widely suggested to be in Indochina. To test this hypothesis, our team measured precisely the elemental abundances of Australasian tektites and compared them to the “BeLaU” composition retrieved from the IM1 site.
Four representative Australasian tektites were chosen for our analysis. The tektite samples originated from Florieton, South Australia and Charlotte Waters, Northern Territory of Australia and two other unspecified origins within Australia. The samples were characterized to be glassy, homogenous, and dark brown or black and oblong or rounded in shape.
The elemental abundances of the four tektite samples and the average upper continental crust were compared to the BeLaU-composition. Our team found that the elemental abundances of the tektites are all very similar with respect to one another and resemble the abundance of the upper continental crust.
Regarding molybdenum (Mo), the BeLaU spherules and the Australasian tektites exhibit opposite normalized enrichment patterns, with the former enriched, and the latter depleted. While concentrations of Be and U of the BeLaU composition exhibit enrichment compared to the upper continental crust, those of tektites are more similar to the crust. A direct comparison of the elemental abundances of the tektites and BeLaU demonstrate beyond a reasonable doubt that Australasian tektites are unlikely candidate material for the BeLaU spherules.
Our study also indicates that the BeLaU-composition is different from laterites. Laterite is a residual material formed by the intense, long-lasting chemical weathering of parent rocks in warm, humid climates with seasonal rainfall, resulting in a soil or rock rich in iron and aluminum oxides and hydroxides. Their element composition does not match the BeLaU pattern either.
In summary, it is relatively easy to come up with speculative hypotheses regarding the origin of the BeLaU spherules. But our detailed analysis argues that speculations associating BeLaU-spherules with common terrestrial materials were unsubstantiated.
New scientific knowledge is not dictated by critics, science popularizers or influencers, but by those who do the hard scientific work. Paraphrasing John F. Kennedy’s Moon Speech: We chose to go to the IM1 site in the Pacific Ocean and do the related scientific analysis, not because they are easy but because they are hard; because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one we intend to win, and the others, too.
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.