In Arthur C. Clarke’s 1973 novel Rendezvous with Rama, a 50-kilometre-long cylindrical spacecraft flies into the Solar System. A space mission is mounted to intercept and study the alien ship, before it flies back out again. Now, remarkably, science fiction is morphing into fact. Astrophysicist Avi Loeb of Harvard University believes that ‘Oumuamua – a mysterious interstellar object that flew through the Solar System in 2017 – may have been an alien artefact.
‘Oumuamua was spotted by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) at the Haleakalā Observatory in Hawaii. It was like nothing ever seen before in the Solar System. From fluctuations in the sunlight that it reflected, astronomers deduced that its shape was most likely that of a flat pancake the size of a football pitch. Most strikingly, the path it followed suggested something was affecting it other than the Sun’s gravity. This happens to comets. These giant snowballs “outgas” material, which acts like a rocket exhaust. Loeb says there was no sign of outgassing. So what was propelling the object through space?
Loeb thinks that, taken together, ‘Oumuamua’s peculiar characteristics indicate it was artificial. He has raised $2 million from private donors to search for the next ‘Oumuamua, and to design a robotic mission to fly by it and take close-up photographs. Not lacking ambition, he envisages this costing $1 billion.
Critics, such as Chris Lintott of the University of Oxford, have countered that we simply didn’t get a good enough look at the thing. The amount of outgassing necessary to explain the object’s motion would have been too small to be spotted by telescopes. But whether ‘Oumuamua was artificial or not, it has got people thinking more about extra-terrestrial (ET) technology.
Currently, the search for extra-terrestrial intelligence, carried out by bodies such as the SETI Institute, looks for intelligent radio signals and “bio-signatures”, such as oxygen and methane, in the atmospheres of planets around other stars. We now know of more than 4,000 planets outside of our Solar System. But ET civilisations may use radio communication technology for only a brief time in their history. As for oxygen, there was little in the Earth’s atmosphere for the first two billion years of life existing on its surface. Both oxygen and methane can have non-living sources, so these molecules may not be the indicators of life that everyone thinks.
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Loeb wants to focus instead on searching for alien technology, starting within our Solar System. The Earth has weather and geological activity which remake its surface, so any ET artefact would be hard to find. Bodies with surfaces that do not change, like the Moon, would be a better bet.
The prospect of finding alien tech on the lunar surface inevitably conjures up the movie version of another Clarke novel, 2001: A Space Odyssey, in which a buried “monolith” is discovered in the Moon’s Tycho Crater. Created by extra-terrestrials, it was left as a kind of “cosmic alarm”. When exposed to sunlight, it emits a high-pitched radio signal, indicating that we humans have mastered space travel, and are ready to pass on to our next evolutionary phase.
Looking for signs of artefacts beyond the Solar System is harder. A good bet, Loeb believes, is to look for chemicals produced by technology. He suggests compounds like chlorofluorocarbons, or CFCs, once used on Earth as refrigerants and spray-can propellants. He thinks they could be detected in the atmosphere of planets around nearby stars by NASA’s James Webb Space Telescope, launched last December.
We can also look for alien megastructures. For a time, it seemed as if KIC 8462852, also known as Boyajian’s Star, might have been orbited by such an object. The star was experiencing significant dips in brightness, and one theory suggested that aliens might have built a megastructure to harvest its sunlight. But the behaviour turned out to be caused by dust in the Solar System.
There are other possibilities, however. Loeb says we should be looking for signs of space travel. Also, if an alien civilisation collected starlight by covering its planet with photovoltaic panels (similar to solar panels) it would cause its surface to reflect light differently from rock and ocean. Loeb is optimistic about finding extra-terrestrial tech because most stars were formed billions of years before the Sun: plenty of time for advanced civilisations to arise. “For that reason, I think the chances are very good,” he says.
This piece is from the New Humanist summer 2022 edition. Subscribe here.
