"Light sail of the same size were designed and built our own civilization, including the IKAROS project and Starshot".
Astronomers from the Harvard Smithsonian Center for Astrophysics (CfA) have detected an unexpected boost in speed and shift in trajectory in the red object named Oumuamua as it passed through the inner solar system.
It withstood collisions with gas and dust-grains, as well as stresses from the rotation and tidal forces of space, according to researchers. Loeb calculated that for it to be a random object following a random orbit, there would have to be 100 million times more of its type hanging around in the solar system. That means the object would be made of some thin material that could absorb radiation from the sun - either a naturally created material we've never seen before, or something made by aliens. "Technology the light sails can be used to transport cargo between planets or between the stars", the researchers note.
However, its flattened, elongated shape, combined with the way it accelerated on its way through the solar system set it apart from conventional asteroids and comets.
Bailer-Jones, who earlier this year led a group of scientists who identified four dwarf stars as likely origin points for Oumuamua, raised questions in particular about the object's tumbling motion.More news: Sculptor who made Mohamed Salah statue explains why it went wrong
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On its face, the study is trying to reconcile 'Oumuamua's pattern of acceleration, which matches that of a comet, to other observations that suggest it's not an active comet.
Astronomers were sure that the object was not a member of our solar system and came from some distant world in the universe. "But we should examine anything that enters the solar system from interstellar space in order to infer the true nature of Oumuamua or other objects of its mysterious population".
"Any functional spacecraft would nearly certainly retract its solar sail once in interstellar space to prevent damage", Jackson said.
Of course, the pair aren't claiming that Oumuamua's definitely of alien origin.
The theory, which the scientists call "exotic", comes from a recent paper they wrote which was published online in November.
It's also entirely possible - perhaps more possible - that the object isn't part of a far-flung alien race's attempts to investigate the (other) occupants of the Milky Way.