Just Passing Through

The need to keep a look-out at all times. Published by Del Rey/Random House Publishing 1986. Cover art by Michael Whelan.

Oumuamua caused a bit of a stir when it was first detected last October – the first object moving through our Solar System that has been shown to be of interstellar origin. It was detected using the Pan-STARRS telescope facility at the Haleakala Observatory in Hawaii, which carries out a continual search for Near-Earth Objects and has identified a large number of asteroids. Oumuamua is believed to comprise metal-rich rock similar to some types of asteroid that originated rather closer to home.

The reason it really hit the headlines, though, was its unusual elongated shape which appeared in some artists’ impressions to bear a resemblance to a Star Destroyer out of Star Wars, or perhaps the cylindrical spacecraft which entered the Solar System in Arthur C Clarke’s 1973 novel Rendezvous with Rama. But no, it’s not an alien spaceship, though for a little while it tweaked our imagination.

By coincidence, it is an asteroid search at the Mauna Kea Observatories in Hawaii that forms the (fortunately fictional) basis for the detection of a huge alien spacecraft in Larry Niven and Jerry Pournelle’s 1985 novel Footfall. Examining astronomical photographs through a blink comparator, it is found to be on a hyperbolic orbit and decelerating as it moves towards the inner Solar System. The US President explains to an amazed population that it “is approaching the Earth along a path that convinces our best scientific minds that it is under power and intelligently guided.”

And when it’s discovered that the spacecraft, which appears to have been a sort of Bussard ramjet, has dropped a massive part of its structure that it would presumably have needed if its occupants intended to leave the Solar System again, the conclusion is disturbing – they mean to stay. But then, many people would have tended to agree with the thoughts of a Congressman who believes “that conquering another planet across interstellar space just isn’t cost-effective.” Which only goes to show how wrong you can be. Fortunately, humanity has a little bit of advance warning since this vessel looks nothing like a natural asteroid, not that that helps very much in the long run.

Having said that, a hollowed-out asteroid might provide a partly ready-made vehicle for off-world colonies in space, on the lines suggested in George Zebrowski’s 1979 novel Macrolife. The idea has often appeared in science fiction, though in Greg Bear’s Eon from 1985 the living space inside turns out to be much, much larger than expected. It might also be particularly suitable for long-distance, even interstellar, journeys if the natural rock could provide protection against the many hazards of space travel, an early representation being in Milton Lesser’s 1953 story The Star Seekers, though natural materials aren’t necessarily the best since they can be subject to various weaknesses which you wouldn’t want to crop up part-way through such a trip. Maybe not all they’re cracked up to be.

Even so, for an exceptionally long-lived society, or travellers in suspended animation, moving around the Galaxy in such a structure could be a distinct possibility. They might even arrive in our backyard.

But let’s not get carried away here. Oumuamua is estimated to be something around 230 metres long – not a patch on the vast size of the fictional Star Destroyers, and certainly insufficient for a rotating space habitat on the scale of, say, an O’Neill colony. Once you allow for essential life support and a reasonable propulsion system, there’s not much room left for a grand invasion force. Unless, of course, the inhabitants are particularly small and, needless to say, size isn’t everything.

Anyway, it’s leaving the Solar System now and will, in due course, resume its journey through interstellar space. Next time something like this turns up from the depths of space, we might be ready to examine it in a bit more detail. Unless, perhaps, it starts examining us in detail first.

Richard Hayes, Assistant Editor (Odyssey)

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