In my car, even at 100 kilometres per hour, I perceive that I’m travelling along quite quickly. In the nice saloon in our car pool, you can reach up to 160 kilometres per hour without it feeling that much faster. Of course, this is because you cannot perceive speed alone. You can notice accelerations, but when you are travelling at a constant speed, you can only tell how fast you are moving relative to other objects – or perhaps when the car begins to rattle. It is the same on the ISS. The speed of the Space Station is much greater – it needs to travel at 28,000 kilometres per hour so it doesn’t ‘fall down’. read more