The Dragon Capsule from SpaceX has just docked successfully with the International Space Station. It carried four astronauts to the orbiting space station; they will live there for the next six months. It was reported by the Guardian here.
Looking at the picture in the report, I was struck by how close the Earth seems. And in fact, it is! Although the ISS was 422 km above Idaho at the time, that’s just not that far… It’s in space, really in space, but it turns out space is quite close to us…
This diagram shows how far out from the Earth the UK would project if we could stand it on end…
And now this one has a red circle corresponding to the orbit of the ISS…
In contrast, we’d have to stack about 400 UKs end-to-end to walk (not really!) to the moon. So when you watch First Man or other films about the Apollo missions to the moon, think how much further out that was than ALL the crewed space travel since, which has been in Earth orbit – essentially near the red line…
And to carry on the UK analogy even further, it takes about 8 hours to travel by train from London to Aberdeen – most of the way up the UK (admittedly, this is when the UK is lying horizontally on the ground). And yet Dragon’s journey to the ISS took 27 hours! Rockets are NOT slower than UK trains, trust me – this is a function of the number of slowly enlarging orbits that dragon made to reach its destination. The destination might be 422 km away, but the flight path is a long one. Check out the flight path in NASA’s press kit.
I’ve written about the scale of the atmosphere and Earth’s gravitational field in more detail before. If you’re interested, try these: