Oumuamua is not alien technology

Unfortunately, ET and his friends have not come for a visit: scientists say that alien technology is not behind solar system newcomer Oumuamua...

First spotted on 19 October 2017 by astronomer Robert Weryk using the Hawaii-based Pan-STARRS telescope, the object was reported to be between 100 and 1,000 metres long and over 150 metres at the widest point. Bizarrely, it was also accelerating on its course and its high velocity relative to the Sun meant that an origin within the Solar System was very unlikely. As a nod to its extra-solar origins, and speculation that perhaps this was an alien spacecraft, it was given the name 'Oumuamua', which means 'scout' in Hawaiian.

But this week, the journey for this ET came to an end. Writing in the journal Nature Astronomy, a team of 14 scientists have scrutinised the observations of Oumuamua and reached the slightly disappointing conclusion that this is definitely not an alien. In their paper, each trait of Oumuamua’s flyby that raised alien suspicions has been explained as a natural phenomenon. “There’s no reason to think this is artificial, everything we observed can be explained by it being a natural object,” comments Alan Fitzsimmons, co-author and professor of Astronomy at Queen's University Belfast.

The detection of interstellar objects has been anticipated for decades now, yet Oumuamua was able to stump the science community for years. When first observed, the object seemed to have a brightness signature that resembled that of an elongated ship. When looking back at the data though, the team found that significant variations in brightness signatures also show that this object would have been tumbling over multiple axes. So any aliens aboard would have to be very resilient to vomiting if they wanted to survive their trip!

“If it was an alien spaceship, it’d be pretty much out of control,” says Fitzimmons.

Another troubling issue was the object’s non-gravitational acceleration, which led some to believe that Oumuamua was actually a solar sail, a device that relies on a star’s sunlight to propel it forward. The team found that this ‘artificial’ acceleration is seen naturally from  objects such as comets. Comets are icy rocks and when the sun’s intense rays hit their ice, gas is released that can propel the object in the opposite direction. From the team's data, it is not 100% clear whether Oumuamua had sufficient ice for this propulsion, but that is due to restrictions in telescope sensitivity.

“We have to remember that Oumuamua - at its brightest - was a pretty faint object that you needed a very large telescope to detect clearly,” Fitzsimmons points out. Despite not having sensitive enough equipment, the team found that it is more than possible that Oumuamua had these gas emissions.

Now that astronomers have had the chance to record the first-ever interstellar object from outside our solar system, future sightings can be improved upon greatly. In just three years time, the Large Synoptic Survey Telescope (LSST) in Chile will be able to increase our detection rate from 1 every 10 years to 1 every year. On top of that, the Comet Interceptor mission has been approved and could be active as early as 2028. The mission will put a probe in orbit just past the moon and it will have the ability to intercept any visitors that wander close enough.

“It may be that within the next 15 years we even get a close-up view of one of these natural objects from another planetary system,” says Fitzsimmons. “Which will be incredibly exciting...”