Bob McDonald's blog: Interstellar asteroid shows uncanny parallels to an Arthur C. Clarke sci-fi novel

Bob McDonald's blog: Interstellar asteroid or starship?
This artist's impression shows the first interstellar asteroid, Oumuamua. It seems to be a dark red highly-elongated metallic or rocky object, about 400 metres long, and is unlike anything normally found in the Solar System. (M. Kornmesser/ESO)

The recent passage of an oddly shaped, interstellar asteroid  through our solar system delighted astronomers. To me, it was eerily foretold in 1973 by science fiction writer Arthur C Clarke. But in the fictional tale, the object was an alien spaceship.

Astronomers first spotted the rogue asteroid named Omuamua, on Oct. 19. It had come in at incredible speed from high above our solar system, travelling at 137,921 km/hr (85,700 mph) on a trajectory that took it on a hyperbolic swing past the sun. Its flight path showed that it had come from interstellar space. And after receiving a gravity assist from our star, it would be cast back out to the realm between the stars, never to return again.

Adding to the excitement over the first glimpse of a visitor from another solar system was the object's unusual shape — 400 metres long and very thin, like a cigar rather than the more rounded shapes found among other asteroids.

This scenario fits almost exactly with that portrayed in the science fiction novel, Rendezvous With Rama.

In the story, set in the year 2131, a similar, but much larger elongated object, 54 kilometres long and 20 kilometres in diameter, is spotted coming in at 100,000 km/h. Fortunately, in the future, humans have the capability to send an intrepid crew of astronauts out to meet the strange visitor from afar, only to discover that it is an alien interstellar spaceship that just happens to be passing through our region of space with no intention to make contact with Earth. What our astronauts find inside will be left to the reader, but the parallels to this month's asteroid flyby are is uncanny.

Or was it an asteroid?

Sadly, we do not have the capability today to send a crew out to rendezvous with the asteroid and find out if anyone is living inside it (doubtful), because it is travelling too fast for our current rockets to catch it. One group has calculated what it would take to make such a rendezvous, and the private company Space X is designing a huge rocket for Mars exploration that could pull it off, but such a mission is far off in the future.

Oumuamua had come in at incredible speed from high above our solar system, travelling at 137,921 km/hr (85,700 mph) on a trajectory that took it on a hyperbolic swing past the sun. (ESO/K. Meech, et al.)

For now, large telescopes will follow Omuamua for the next few months, then it will be gone forever.

Another aspect to consider in this flyby is that although it is the first interstellar object to be spotted, there are likely many more out there that we haven't seen, including many that have already passed through our solar system.

The odds of an asteroid hitting the Earth are very real, as the dinosaurs found out 66 million years ago. But a strike from an interstellar asteroid could be more severe because the objects are travelling much faster than those that come from within our solar system. A typical asteroid hits the Earth with a velocity of about 30 km/s, which is very fast, but our alien visitor whipped by the sun at 87.4 km/s, so even a small object carries a huge amount of destructive energy.

Finally, this object was spotted after it had already whipped around the sun and was on its way out. In other words, we didn't see it coming. That is a problem because if one is heading our way, we need as much lead time as possible to nudge it out of harm's way. A small nudge while it at a great distance is enough to cause it to miss the Earth. The closer it gets, the more you have to push it because the Earth becomes a much easier to hit target.

Our alien visitor is a reminder that space is full of rogue objects wandering among the stars. If we spot another one heading straight for us, it would be in our own interest to be ready to go out and meet it, whether it is an alien spaceship or not.


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