[amsat-bb] Re: Multiple satellite launches (rates?)

Robert Bruninga bruninga at usna.edu
Mon Nov 25 13:35:21 PST 2013

>  The following link is of Picodragon and 2 other satellites

> being released from ISS. There is a picture and short video.

> http://amsat-uk.org/tag/picodragon/

Looking at the video, my uncalibrated eyeball counts the deployment rate at
about ½ meter per second? Ie, in the first second of video, the 3 cubes
move about the same distance as their overall combined length.   And in 2
seconds about the same again.

Using the still photo at the top of the page, I estimate about 10cm of
additional spacing between the 3 cubesats total or about ½ meter for this
overall length.  Of course there is some parallax difference between the
two views, but my guess is about 1/2m per second if the frame-timer in the
video is a rough guess.

But this is the ISS launcher which might be different from the PPOD
launchers on the Dnepr and Minotaur.  Just guessing of course..

Bob, Wb4aPR

-------------original message ---------------------

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
downlink experience.

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…

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