The ISS is around 400km above us. A rocket needs a speed of at least 8km per second to get to space. If we cut out the acceleration part it could in theory reach the ISS in around 50 seconds. Even if we factor in the acceleration part etc. it should still be very quick up there. Yet the fastest possible time to get to the ISS is 4 hours. That would be an average speed of 100Km/h which is way slower than the speed of the rocket after a few seconds. Why the long journey?
In: Planetary Science
In the simplest terms: getting to the ISS isn’t about traveling the 400 km, it’s about accelerating to 8 km/s (28000 km/h) and ending up in the right place at the right time, so that the relative speed if you and the ISS is about zero. If you went straight up and parked yourself in ISS’s way, you would only get an extremely high speed crash (at Mach 28!) Fun fact, we actually overshoot the station at first and use the magic of orbits to let it catch up to us. Watch [this magnificent bastard explain the current speed record :).](https://www.youtube.com/watch?v=bUi0yWc5Dnw)
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