Re: Collision risk

Dave Mullenix (
Wed, 28 Feb 1996 03:39:00 -0600

>On a slightly different subject vis-a-vis TSS and its tether, Philip Chien
>> ... yeah there's a one in kazillion chance that the satellite and tether
>> would run in to another spacecraft, or even tangle up into Mir's
>> structure, but not enough to be a concern.  There's been plenty of
>> other debris which has been put up their accidentally and hasn't
>> been a concern (e.g. HST solar array, SFU solar arrays, etc.)

Rob Matson replies:
>There's a world of difference between the tether and a solar array.  This
>isn't an area issue -- it's a cross-section intersection issue, and linear
>dimension becomes more important.  The probability of a 10-meter by 3-meter
>solar array intersecting a particular 1 square-meter cube (say) is hundreds 
>of times smaller than a 20-km tether intersecting that same volume, even 
>if it IS only 1/10" thick.

And finally, I have my say:
If I remember right, debris cut the SEDS tether TWICE.  I think the
first cut released the satellite and the second cut chopped the
trailing tether in two.  I remember being surprised it was even hit

Of course, the chances of the tether being hit by debris in the 
portion that was inside the launch tower are much lower than the
chances of a 20 km long tether being hit anywhere in its length.