There are so many satellites orbiting Earth now at various altitudes and there is quite a lot of space junk floating around as well.

Now although there are so many satellites and so much junk up there the probability of a collision is extremely low.

When launching a spacecraft/rocket (take Musk's recent launch), do they take into account the positions of the other satellites or do they just ignore it as the probability of a collision is still extremely low ?

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    $\begingroup$ They would be stupid, if they didn't take all available info. Each launch is costly and checking the trajectory against those of known space debris and active satellite does not cost much. $\endgroup$ Jun 10, 2020 at 15:44
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    $\begingroup$ Related: space.stackexchange.com/q/40476/9060 $\endgroup$
    – Chris
    Jun 10, 2020 at 16:00
  • $\begingroup$ Of course they do! $\endgroup$
    – User123
    Jun 10, 2020 at 16:10
  • $\begingroup$ @planetmaker To be precise, the additional cost per launch is not much. The worldwide tracking systems are expensive both in hardware and manpower, but as with insurance policies, the cost per "use" is relatively low compared with the potential loss of a launch. $\endgroup$ Jun 10, 2020 at 17:24
  • $\begingroup$ These junk occurs so uniformly randomly that there's not much you can do to avoid them by moving launch window around. $\endgroup$ Jun 10, 2020 at 17:30

1 Answer 1


mentions this:

Launch windows

Collision avoidance is a concern during spaceflight launch windows. Typically, a Collision On Launch Assessment (COLA) needs to be performed and approved before launching a satellite. A launch window is said to have a COLA blackout period during intervals when the vehicle cannot lift off to ensure its trajectory does not take it too close to another object already in space.


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