Last year, a cigar-shaped object, unlike any mankind had ever seen before, entered into our solar system. Scientists spent some time deliberating about whether the strange object was an asteroid or comet before ultimately being forced to conclude that this unusual new visitor was actually the first of an entirely “new class” of interstellar objects. That mystery only deepened as the object, which scientists dubbed “Oumuamua,” seemed to accelerate as it traveled through our solar system.
The object’s name, “‘Oumuamua,” is a Hawaiian word meaning “a messenger that reaches out from the distant past,” and according to a new paper published by researchers at the Harvard Smithsonian Center for Astrophysics, that name may be exactly right.
“‘Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization,” the paper asserts. Crazy as such a theory may seem, there’s actually some interesting evidence to support it. The team went on to posit that the technology that could have been employed on ‘Oumuamua may actually have been something humans are already familiar with.
“Considering an artificial origin, one possibility is that ‘Oumuamua is a light sail, floating in interstellar space as a debris from an advanced technological equipment,” the paper postulates. “Light-sails with similar dimensions have been designed and constructed by our own civilization, including the IKAROS project and the Starshot Initiative. The light-sail technology might be abundantly used for transportation of cargos between planets or between stars.”
Light sails are considered among the most efficient means of space travel — and surprisingly — are among the fastest forms of propulsion mankind has yet to develop; or at least it could be in theory. It works much like a sail does on the ocean’s of earth, but instead of catching wind, a light sail is bombarded by light particles. Each tiny collision provides a small push to the sail. In the near vacuum of space, there’s nothing to slow the sail once it begins accelerating, so conceivably, a light sail will continue to accelerate until it reaches some fraction of light speed — provided it has a continuous source of light behind it that’s close or powerful enough to reach it. Some scientists have postulated that directed energy beams from lasers could help propel future light sail vessels.
The problem with light sails, however, is that while they may boast an extremely high potential top speed, they’re also extremely slow to accelerate. It would take far longer to reach Mars via light sail than it would with a conventional rocket, making light sails a logical propulsion system for long-range exploration, perhaps, but not for crewed space flight.
If Harvard’s team is right, ‘Oumuamua may have been a derelict light sail.
“This would account for the various anomalies of ‘Oumuamua, such as the unusual geometry inferred from its light-curve, 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,” the paper reads.
‘Oumuamua isn’t the only space object scientists have seen accelerating as it travels through orbit. The gravitational pull of large bodies like planets or stars can create a slingshot effect that provides an orbital body with a boost of acceleration and comets are known to accelerate due to “outgassing” as the sun melts ice on the comet itself and it expels gasses. ‘Oumuamua, however, accelerated in a manner that wasn’t in keeping with its orbital trajectory and didn’t expel any visible gas, leaving scientists perplexed.
Was ‘Oumuamua a lost spacecraft from a far off civilization? Chances are good that we’ll never know for sure. All we can say for certain is that, whatever it was, it was unlike anything we’ve ever seen before.