ʻOumuamua is the first interstellar object detected passing through our Solar System.
A new study considers the possibility that "‘Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization." This study has not yet made it through the scientific peer-review process but the possibilities are worth consideration.
Below are a few excerpts.
"A survey for lightsails as technosignatures in the Solar System is warranted, irrespective of whether ‘Oumuamua is one of them."
"We discuss the possible origins of such an object including the possibility that it might be a lightsail of artificial origin."
"We explore the possibility that the excess acceleration results from Solar radiation pressure."
"The large variations in its apparent magnitude and the non-trivial periodicity of the lightcurve, suggest that ‘Oumuamua is rotating in an excited spin state (tumbling motion),
and has an extreme aspect ratio of at least 5:1 ... an unprecedented value for pre-viously known asteroids and comets in the Solar System."
"if ‘Oumuamua rotates in its highest rotational energy state, it should be extremely oblate (pancake-like)."
"despite its close Solar approach of r = 0.25 AU, ‘Oumuamua shows no signs of a any cometary activity, no cometary tail, nor gas emission/absorption lines were observed."
"If not cometary activity, what can drive the non-gravitational acceleration observed? In this Letter we explore the possibility of ‘Oumuamua being a thin object accelerated by Solar radiation pressure, which would naturally result in an excess acceleration"
"If radiation pressure is the acceler-
ating force, then ‘Oumuamua represents a new class of thin
interstellar material, either produced naturally,through a yet unknown process in the ISM or in proto-planetary disks, or of an artificial origin."
"Considering an artificial origin, one possibility is that ‘Oumuamua is a lightsail, floating in interstellar space as a debris from an advanced technological equipment"
"Lightsails with similar dimensions have been designed and constructed by our own civilization, including the IKAROS project and the Starshot Initiative2"
"This would account for the various anomalies of ‘Oumuamua, such as the unusual geometry inferred from its lightcurve"
"its low thermal emission, suggesting high reflectivity and its deviation from a Keplerian orbit without any sign of a cometary tail or spin-up torques"