Interstellar Panspermia by 'Oumuamua-like Interstellar Asteroids and Comets, and the Implications for Biological Contamination of the Early Earth


  • Michael Summers Aspiring Scientists' Summer Internship Program Mentor
  • BILL CHEN Aspiring Scientists' Summer Internship Program Intern



The discovery of the interstellar comet 'Oumuamua on October 19, 2017 by Robert Weryk using the Pan-STARRS telescope at Haleakal Observatory, Hawaii has radically changed our understanding of interstellar space. 'Oumuamua was an interstellar object that had been formed in a distant solar system, probably by the collision between two planets, then ejected into space nearly 400 million years ago, before it passed through our solar system. This discovery implies that interstellar space has 100,000,000 times more planetary system debris than previous models had predicted. This raises the question, if 'Oumuamua-like objects are highly prevalent in the interstellar medium, could biological life be able to transfer between planets in different solar systems? Based on the now known density 'Oumuamua objects per unit volume (2.4 × 10^-2 AU^-3), we find 'Oumuamua size objects (100 m) will impact the Earth, bringing approximately 2.3 x 10^-9 g/cm2 per million years. Using a power law distribution, we also calculated that interstellar objects at 1.2 and 1.4 the size of Oumuamua will bring 1.239 × 10^-7 and 6.196 × 10^-6 g/cm^2 per million years, respectively. Considering the high likelihood of collisions and that biological organisms are known to survive in space for extended periods of time under 1 meter of shielding, this has important implications for the likelihood of transfer of microbial life between Earth and planets in other solar systems. This suggests that the early Earth was the recipient of significant amounts of material from distant solar systems during the time that life is thought to have originated on Earth.





College of Science: Department of Physics and Astronomy