Reconstruction of the first interstellar meteor

Now that we’ve measured the composition of the first known interstellar meteorite, IM1, can we recreate its materials in the lab?

The stress IM1 endured before it disintegrated meant that it was once the most powerful of the solar system’s iron meteorites. This raises important questions: What is IM1’s melting temperature, thermal conductivity, material strength, or electrical conductivity?

Given the measured excesses of beryllium (Be), lanthanum (La), and uranium (U), dubbed “BeLaU”, by factors of hundreds over solar system rocks, it is interesting to know whether IM1 is natural or technological. . Originally.

If IM1 is normal, it could be the product of a planet with a magma ocean and an iron core, with iron-bound elements sinking towards the core and other elements remaining in the planet’s crust reflecting the pattern of ‘BeLaU’ abundance found on our new planet. Scientific paper. After intense work and long sleepless nights over the summer, the paper was published on the arXiv preprint server on August 29, 2023, exactly two months after we returned from the expedition.

In an unprecedented gesture, arXiv officials chose to highlight the paper with a dedicated video featuring a summary of the paper’s findings, read out by artificial intelligence (AI). arXiv director Stein Sigurdsson emailed me the idea that if IM1 is technological in origin, the enhanced abundance of heavy elements in “BeLaU”-type globules could be due to the fact that LaO over Mo or W sulfide substrates are promising materials. . For two-dimensional semiconductors in nanotechnology fabrication. Of course, everyone knows that U is used in fission reactors.

I am pleased that there is more to be learned from further analysis. The radioisotopes in the “BeLaU”-type pellets can be used as clocks based on their known half-lives and the relative abundance of the daughter and mother nuclei. The genius Stephen Wolfram emailed me a list of a wide range of useful isotopes with half-lives suitable for measuring the duration of interstellar travels, including plutonium-244 at 81 million years, uranium-235 at 0.7 billion years, and potassium-40 at 81 million years. Uranium-235, which has 0.7 billion years, and potassium-40, which has 81 million years. 1.25 billion years, uranium-238 at 4.46 billion years – which is equivalent to the age of the solar system, and thorium-232 at 14 billion years – which is similar to the age of the universe. Unfortunately, the decay product of uranium, lead (Pb), is volatile and is lost by evaporation in the IM1 fireball at temperatures of thousands of degrees.

Dimitar Sasilov pointed out to me that another way to estimate the duration of the interstellar journey is from the abundance of beryllium, which accumulates over time as a result of fragmentation by interstellar cosmic rays. As I looked up through a starry night on the deck of the M/V Silver Star exploration spacecraft, it occurred to me that measuring IM1’s flight duration and multiplying it by its known velocity outside the solar system could tell its distance and direction. From the star source. This provides a unique opportunity to identify the IM1 sender’s mailing address.

But can we know what was used in the IM1 package that arrived on our doorstep?

The Cake Recipe Book includes a list of ingredients and their relative contributions to the mix. We have this list of IM1 components, excluding the volatile elements that were lost due to evaporation during the meteor fireball. Can we add the missing components as reasonably as possible, mix the items and check what ‘cake’ we get for IM1?

While mixing all the relevant elements in a lab can be expensive, AI offers another way forward. We can simulate the “cake” by mixing the ingredients and measuring the properties of the composite alloy on a computer. Before I go for my morning jog at sunrise, I email a professor in the Department of Materials Science and Mechanical Engineering at Harvard University who has developed AI code to simulate the properties of alloys. My request was for him to simulate the configuration of IM1 and calculate the properties of the product.

The simplest way to reconstruct IM1 is to find a large chunk of it lying on the ocean floor. The fireball’s heat may have eroded only the surface of IM1, leaving its major components on the ocean floor. To find them, we’re planning a future expedition using sonar imaging equipment that can distinguish IM1 fragments from ground rock. Now that we’ve mapped where the IM1 globules are located relative to the background material in the control regions we scanned, we can predict where the large chunks might fall based on their size. The force of friction exerted by air scales with area, while the force of gravity scales with volume so that smaller objects decelerate faster due to the larger area-to-volume ratio. As with raindrops, terminal velocity depends on the balance of the two forces and increases with size. All of this can be taken into account to predict the expected location of larger IM1 fragments, depending on their sizes.

The task is challenging but the rewards are inspiring. To paraphrase John F. Kennedy at Rice University about the space effort during my birth year, 1962: “We chose to go to The Pacific Ocean this year And we do the other things, not because they are easy, but because they are difficult, because that goal will organize and measure the best of our energies and skill, because that challenge is the challenge we are willing to accept, the challenge we are unwilling to postpone, and intend to win.”

The ‘BeLaU’ formation pattern of IM1 globules has not been previously reported in the scientific literature and has not been found in our control regions – the recovered globules have the composition of the Solar System. Most of my career has focused on theoretical physics, projecting what the universe should look like. This summer I chose to lead an experimental project. This interstellar expedition convinced me of the words of Yogi Berra: “In theory, there is no difference between theory and practice. In practice there is.”

Avi Loeb is Head of the Galileo Project, Founding Director of the Harvard Black Hole Initiative, Director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and Past Chair of the Harvard Astronomy Department (2011-2020). He chairs the Breakthrough Starshot Project Advisory Board, is a former member of the President’s Council of Advisors on Science and Technology and a past chair of the National Academies’ Board of Physics and Astronomy. He is the bestselling author of Extraterrestrial: The First Sign of Intelligent Life Beyond Earth and co-author of the textbook Life in the Cosmos, both published in 2021. His new book, Interstellar, is due out in 2021. Published in August 2023.