One of the first sci-fi books I ever read was Rendevzous With Rama by Arthur C. Clarke. I was only about twelve years old, and it left a lasting impression. My imagination has been running overtime for the better part of twenty years because of it; after all, what would it be like to have an extraterrestrial object ploughing through our solar system? What would that mean for mankind?
We don’t have to look far to find the answer. There is an object coming through our system right now. Its name is A/2017 U1, and it’s almost certainly a comet. It made its closest approach to the to the sun on September 9, and is now zooming away at 97,200 mph—more than enough to take it back into interstellar space. In truth, that’s the end of its story - it was detected too late for us to send any sort of mission to it, let alone design and fund one!
Imagine that A/2017 U1 wasn’t a frozen ball of ice, though. What if, like in Arthur C. Clarke’s Rendezvous With Rama, it was a ship sent from another civilisation. Even if it had no interest in us, and was simply using our star as a slingshot to its next destination, would it have any impact on us?
To start with, it would no doubt mean that we are not alone in the universe—or, to be more precise, we have not always been alone. Just because we have come across a product of an alien civilisation doesn't necessarily mean that said civilisation is still around. However, it would be foolish to assume that it is not.
Secondly, it could well shake the very foundations of many of the world's belief structures. This wouldn’t be the first time that this has happened; just look at the introduction of Darwin’s theory of evolution. Of course, religion has endured through the advent of many a scientific discovery, and would most likely survive a close encounter of the third kind as well.
Thirdly, and quite possibly most importantly, there is a very real chance that this foreign object could be a threat. That might sound slightly hyperbolic on the surface, but if a civilisation has sent a spacecraft to our solar system, this means that they are far more advanced than us, or. at least, they are if they are still alive. It’s only sensible to assume that they are and to prepare accordingly.
So, what can we do? Maybe nothing, but while that is most probably a realistic attitude to have, it really isn’t particularly helpful.
At our current level of technology, there are indeed weapon systems that are within our reach such as the Relativistic Kill Vehicle. But if, as previously mentioned, this hypothetical civilisation is indeed far more advanced than us—possibly even by millions or billions of years. What do we do?
Unless we are close to the pinnacle of weapons development, there is every chance that we simply have no hope; the extraterrestrial threat could be stronger than our combined military forces are in comparison to the Sentinelese people of North Sentinel Island. The western world is, on the whole, maybe a few thousand years more advanced than they are, but the aliens could be millions or billions of years further along.
Our best hope is that these ET’s have no hostile intent, or simply pay us no attention as if we were ants crawling along a vine. That being said, it is probably wise to proceed as if there is a chance of competition out there amongst the stars, that we do all that we can to reach our full potential, both scientifically and martially. That way we at least stand a chance if we find ourselves in the midst of a dispute with our possible alien neighbours in the future. Of course we should hope for peace and prosperity, but if you want peace you should prepare for war. If you fear war, make sure that you are capable of winning one; if there is other life out there and they are anything at all like us, they will surely do the same.
Maybe civilisations are spread so far apart we will never need to worry about contact, but until we are sure, until the evidence is in front of us, should we not be designing the space faring warships that have so far been relegated to fiction for ourselves?