3 ms·

That is amazing. Seeing the complexity of the grid is mind blowing - and the realization the blocks representing the satellites are the size of cities makes you

• jonplackett 8y ago
  It seems like that doesn't it, but space is MASSIVE. Imagine if there were only 7000 people spread out on the face of the earth, would you be worried you'd accidentally run into one of them? These things are up another few hundred miles so are even more spaced out than that.
  • jessriedel 8y ago
    This is true but not as useful an intuition as it first appears. The major difference for satellites is that everything in low-Earth orbit is traveling at ~8 km/s, so the spatial volume they traverse in any amount of time can be surprisingly large. A cubic-meter satellite traverses 250 cubic kilometers of volume in a year. (If you want to get an order-of-magnitude estimate for collision frequency, you imagine one satellite occupies it's normal volume and the other occupies the traversal volume, and then just ask what the chance is that those volumes overlap, given the amount of space above the Earth within the altitude range of the orbits.) And indeed, there has already been an accidental satellite-satellite collision (not just satellite-debris collision). https://en.wikipedia.org/wiki/2009_satellite_collision https://en.wikipedia.org/wiki/2009_satellite_collision The Iridium constellation has about ~80 satellites, and one passes within 5km of another satellite about 50 times/day.