The recipe for baking a cake does not involve only the ingredients. It also includes a prescription for how much heat to supply and for how long to apply it. Supplying too much heat for too long would result in a burnt crust.
When an object collides with Earth, its surface heats up in an atmospheric fireball as a result of its friction with air. The extreme temperature of thousands of degrees Celsius melts the surface into droplets, called spherules, which rain down. These are the relics that the Galileo Project expedition recovered from the mile-deep floor of the Pacific Ocean at the site of the interstellar meteor, IM1, which collided with Earth on January 8, 2014. After studying the spherules with a mass spectrometer, we identified some of them as having a unique chemical composition, which we labeled BeLaU, unfamiliar compared to the composition of known Solar System spherules.
When studying these spherules under an electron microprobe, our research team noticed that they have a unique morphology. An intriguing challenge for a chef is to examine a cake with known ingredients and figure out its recipe. We know the chemical composition of the BeLaU spherules. Given the known ingredients of this “cake”, can we figure out the rest of the recipe for baking it?
IM1’s fireball was observed by sensors on U.S. Government satellites. The light curve exhibited three separate flares, each lasting for a tenth of a second. As the duration of these heating episodes is known, one could hope to find out the peak temperature to which the BeLaU spherules were heated in the fireball that made them.
During the latest meeting of our research team, the brilliant scientists Drs. Juliana Cherston and Eugenia Hyung presented images of the BeLaU spherule morphology from the electron microprobe in the laboratory of Professor Stein Jacobsen at Harvard University. Following their presentation, I asked Juliana and Eugenia: “Can we determine the temperature that resulted in this morphology?”
Indeed, laboratory experiments studied in the past the morphology of micrometeorites and meteoroids, as a function of the duration of their heating and the resulting peak temperature.
Stein noted that we can do a similar experiment in his laboratory. In that experiment, we will put together the chemical elements that make the BeLaU spherules and heat these ingredients with a short pulse of energy that resembles the short duration of IM1’s flares. By studying the structure of the resulting droplets as a function of their peak temperature, we could figure out the conditions in the fireball that made them. The temperature in Stein’s oven can be an order of magnitude larger in degrees Celsius than the typical temperature used to bake edible cakes.
My daughter, Lotem, who is currently an undergraduate at Harvard College, loves to bake chocolate chip cookies. I often visit the kitchen before and after her baking procedure and so I have a good sense of the ingredients she uses as well as the delicious cookies she makes. But I never developed the skill to make these cookies. The reproduction of the BeLaU spherules will be a learning experience for me. Here’s hoping that after our research team reproduces the morphology of these meteoritic spherules, I will be able to reproduce Lotem’s chocolate chip cookies without too much burnt crust.
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. His new book, titled “Interstellar”, was published in August 2023.
