Insight & Analysis

Interstellar overdrive

Published: Nov 2018

Astronomers believe a 400m long rock hurtling away from the Sun at 70,000 mph could be a ‘light sail’ – debris from an advanced spacecraft that was “on a reconnaissance mission”.

The elongated structure – the first ever detected interstellar object – was spotted by the Haleakala observatory in Hawaii in October 2017 at a distance of about 19m miles from Earth.

There is speculation that with a high metal content and showing no signs of dust, it could be part of a massive alien craft sent to look for signs of life, say astronomers at the Harvard Smithsonian Center for Astrophysics.

The object, formally designated 1I/2017 U1 but now referred to as ‘Oumuamua’ (from the Hawaiian for ‘scout’), curiously exhibits both asteroid and comet properties. Even stranger, it gained an “unexpected” burst of speed as it passed through the inner solar system.

In their paper, ‘Could Solar Radiation Pressure Explain Oumuamua’s Peculiar Acceleration?’, Shmuel Bialy, a postdoctoral researcher at the Institute for Theory and Computation (ITC), and Professor Abraham Loeb, ITC’s Director, suggest that by appearing to gather speed as it left the solar system but not when it was closest to the Sun, Oumuamua may in fact be a form of spacecraft that relies on radiation pressure to generate propulsion.

“Oumuamua could be an active piece of alien technology that came to explore our solar system, the same way we hope to explore Alpha Centauri (a star system some 4.37 light-years away) using Starshot and similar technologies,” said Loeb.

Analysis of its trajectory suggests that it came from far beyond the solar system, possibly in the constellation Lyra, and is now heading in the direction of the constellation Pegasus.

The suggestion that Oumuamua is of artificial origin led one commentator to propose that “this at least proves science accepts that intelligent alien life exists”, demanding to know their whereabouts.

Another observer welcomed the arrival of intelligent life. “Please be aliens,” they said, “I’m so fed up of the current inhabitants on earth, although don’t bother coming if you want to be a reality star”.

Those fearing alien invasion need not worry. According to Davide Farnocchia, a scientist at NASA’s Center for Near-Earth Object Studies at the Jet Propulsion Laboratory, Oumuamua is on “the most extreme orbit” he has ever seen. “It is going extremely fast, and on such a trajectory that we can say with confidence that this object is on its way out of the solar system and not coming back.”

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