An artist’s impression of ‘Oumuamua approaching the sun. Image: ESA/Hubble, NASA, ESO, M Kornmesser
The mysterious ‘Oumuamua interstellar object in our solar system could actually be an extraterrestrial solar sail caught adrift, according to a pair of scientists.
It has been about a year now since astronomers announced the first ever detection of the interstellar object named ‘Oumuamua, the Hawaiian word for scout.
Now, according to Universe Today, a recently published paper could show that its name might have been more apt than we could have ever dreamed of, as it suggests it could be a solar sail of extraterrestrial origin drifting through space. The explosive claim was made by Shmuel Bialy and Prof Abraham Loeb, the latter of whom is director of Harvard’s Institute for Theory and Computation.
As we have seen over the past year, trying to categorise ‘Oumuamua has proven tricky, to say the least, with it having changed from comet to asteroid and back again, all while appearing to have a trajectory that just doesn’t make sense.
Last June, it was revealed the object was actually gaining speed as it exited the solar system, rather than slowing down as expected. At the time, the suggestion was that icy ‘Oumuamua was being heated by the sun, venting material, thereby giving it an extra boost.
Established theory doesn’t make sense
However, Bialy and Loeb question this narrative, asking why, if ‘Oumuamua was a comet, did it not vent gases when it was closer to the sun when observed during an earlier survey? If this phenomenon – referred to as ‘outgassing’ – occurred, it should have caused a rapid evolution in its spin as well, which wasn’t observed.
Rather, the pair suggest that in order for the acceleration to occur, the object would need to be extremely thin – just a few millimetres thick – and at a scale of tens of metres in size. This would suggest a solar sail design similar to what has been proposed by the Breakthrough Starshot team with its planned trip to Alpha Centauri.
“Its origin could be either natural (in the interstellar medium or proto-planetary disks) or artificial (as a probe sent for a reconnaissance mission into the inner region of the solar system),” the researchers wrote.
Calculating what dimensions would be necessary for a sail to survive the perils of interstellar travel, the researchers said it would only need to be a maximum of 0.9mm in thickness, and should be able to withstand collisions with dust grains and anything else small it might come in contact with.
How did it get here?
So, if it is a solar sail, how did it get here? Bialy and Loeb proposed that it could actually be a piece of alien space junk drifting through the cosmos, explaining why there is no radio signal coming from ‘Oumuamua.
Writing recently in Scientific American in September, Loeb said: “This opportunity establishes a potential foundation for a new frontier of space archaeology, namely the study of relics from past civilisations in space.
“Finding evidence for space junk of artificial origin would provide an affirmative answer to the age-old question: are we alone? This would have a dramatic impact on our culture and add a new cosmic perspective to the significance of human activity.”
While they even go as far as to suggest that it could have been on an alien reconnaissance mission to our solar system, Bialy and Loeb admit there are still too many unknowns to categorically prove it is of alien origin. Even if it is just a chunk of natural debris, it could still change our very understanding of the cosmos and what could have created such an object.
Updated, 9.17am, 6 November 2018: This headline was amended to clarify that the interstellar object could be of alien origin.
