The other day, more than usual calls on my cellphone were being dropped. The Internet was erratic and DStv was often on the blink.

An increase in electromagnetic jamming always precedes an attack. The question is: From whom? I considered the options and worked out that it had to be aliens. The first fundamental question is: Where would aliens come from and why? We can generally accept that nobody alien or human would want to travel for more than one year. Thus, if we figure that the alien craft can travel at 30% the speed of light on average, then they would have come from about 0.3 × 3 × 106 m × the number of seconds in a year away, which is about 28 × 1 012 km, which is about 305 × the distance of the earth to the sun.

Scientists would have us believe that there are no habitable planets less than ten light years away. However, by the laws of relativity, time passes more quickly the faster you go, so, probably, the aliens will reach some speed that can cover the appropriate distance in a few years, which will only seem like one year to the passengers. (Interestingly enough, British Airways can make the trip from Heathrow to South Africa, which is, in fact, about 14 hours, seem like two days – it is called ‘reverse relativity’). Back to the aliens.

How many would come and how many ships? What size? The number of ships, I think, is easy: history has shown us that exploration is best done with three ships. Fewer and there is a 50% mutual support requirement. More and the probability of failure is greater. The size, I think, would be about the size of a US nuclear submarine – about 170 m long. If the Yankees can live for a year under water, aliens can survive in space for the same amount of time.

The downside, of course, is that you have to build the alien spaceship in space and it will cost an absolute fortune. Both these are social problems. So, we have to guess that the aliens set off since they had no alternative – possibly, they had worked out that a very large meteor was going to crash into the planet. A nuclear submarine costs about $ 2.4-billion; so, the alien spaceships will cost about this amount.

When the aliens get here, what will they want? If they want a place to stay and a job, it is unlikely that they will get any employment. It is hard enough to get these things, anyway (just ask any Somali in Cape Town).

We do have some places where they are welcome to settle (the Sahara Desert, Patagonia and KwaZulu-Natal) but what will they be doing for gainful employment? Obviously, if they have developed a sizeable spaceship, they can rent it out to various scientists who can take it on trips to see the planets.

There is, of course, the problem of what to do with the alien spaceships – they will be undoubtedly nuclear powered and thus difficult to dispose of. For this reason, they will probably just continue to orbit the earth visible like a slow shooting star at night and this will make most people feel uncomfortable. If we look back to history, never ever have any explorers gone to a foreign land and made peace with the locals. Our alien invasion will not be the first.

It is possible, too, that the aliens will merely be stopping for supplies. Or at least that is what they will say. What supplies? If they have nuclear power, they hardly need oil. Precious metals and diamonds have limited trading value for an alien. They can make their own water. But they probably would like a change of diet. The difficulty with this is that nobody can tell the alien reaction to a medium-rare steak. It is a good chance that on arrival they will shake hands, look around and say: “Um, we won’t be stopping.” I hope so anyway. But gad! What if they like medium-rare steak? Oh dear.