Marvin Ellis of the Harvard/Smithsonian Center for Astrophysics has published a paper on arXiv, “Research Programs Arising from ‘Oumuamua Considered as an Alien Craft” arguing that ‘Oumuamua (1I/2017 U1), the first unambiguously interstellar object to be discovered within the solar system, is sufficiently anomalous, displaying characteristics which are absolutely unique among the more than a million solar system asteroids and comets discovered so far, that the hypothesis it is an artefact created by an extraterrestrial technological civilisation cannot be excluded. While natural explanations cannot be ruled out, most of those proposed presume phenomena which have never before been observed in nature while, after all, we do have one example of a technological civilisation which has the capability to build and launch an object like ‘Oumuamua on an interstellar trajectory—ourselves.
The paper argues that admitting the alien artefact hypothesis as a possibility suggests a number of concrete follow-up research topics in a variety of fields, including planning for study of similar interstellar objects should they be discovered in the future. Here is the abstract.
The controversial hypothesis that 'Oumuamua (1I/2017 U1) was an alien craft dominated by a solar sail is considered using known physics for the two possible cases: controlled and uncontrolled flight. The reliability engineering challenges for an artifact designed to operate for 10^5 - 10^6 yr are also considerable. All three areas generate research programs going forward. The uncontrolled case could be either “anonymous METI” (messaging extraterrestrial intelligence) or “inadvertent METI”. In the controlled case the nature of the origin star, trajectory guidance from the origin star to the Sun, and the identity of a destination star are all undecided. The “controlled” case has more strikes against it than the “uncontrolled” case, but neither suffers a knock-out blow, as yet. Some of the issues turn out not to be major obstacles to the alien craft hypothesis, but others weaken the case for it. Most, however, imply new studies. Some of these, e.g., intercept missions for new interstellar objects, are concepts being developed, and will be of value whatever these objects turn out to be. Overall, these considerations show that a many pronged, targeted, research program can be built around the hypothesis that’Oumuamua is an alien craft. The considerations presented here can also be applied to other interstellar visitors, as well as to general discussions of interstellar travel.