# [amsat-bb] Re: Multiple satellite launches

Robert Bruninga bruninga at usna.edu
Mon Nov 25 07:54:33 PST 2013

```Ø  When there is a launch of several satellites in a single payload,
several cubesats for example,  I assume they release each at
different locations on the deployer trajectory.  Preliminary keps are based
on the trajectory when each is released?

Ø  Otherwise if they were released all at once, how would NORAD know which
is which?

Doesn’t much matter when they are released, they still are all in the same
orbit more or less for quite a while.  Even if the springs release them at
1/2 meter per second, they are all going at 7000 meters per second so it
takes days for them to separate very much.

Let’s see,  at ½ meter per second separation, then they are 100’ apart
after the first minute, 1 mile after the first hour.  And not until they
are a few miles apart can NORAD distinguish them enough to start getting
good tracks on them.  By then it is impossible to know which is which.
Hence the guessing game until each owner decides which object best fits his

Continuing on, they will be 24 miles apart after the first day where they
will be about 5 seconds apart when tracked from the ground.  After a week,
then maybe 175 miles and ½ minute apart.  After a month, maybe 750 miles
and 2 minutes apart.  After a year, maybe 9000 miles and 30 minutes apart.
And finally, after about a year and a half, they will be half an orbit or
about 45 minutes apart, beyond which, they start getting closer again…

Something like that unless I screwed up…

Bob
```