From: Henry Spencer <henry@zoo.toronto.edu>
Newsgroups: sci.space.tech
Subject: Re: ariane 5 has exploded
Date: Mon, 10 Jun 1996 04:08:27 GMT

In article <31B73B5D.1735@den.mmc.com> Rick Cooper <ss8rsc@den.mmc.com> writes:
>> >Or why they can't jettison the payload for parachute recovery?
>
>[...problems of doing so...]
>In addition, in the United States, the Air Force gets very
>nervous of large chunks of hardware falling out of the sky
>Every piece of rocket hardware launched has a Flight Termination
>System to blow it itself into small fragments if it veers of
>course...

No, this isn't quite true, although it's a popular misconception.  When
a rocket is blown up, large chunks of hardware *will* fall out of the sky.
The charges are nowhere near large enough to shred the vehicle.  That's
why the safety people insist on blowing the thing up before it strays far
enough from its intended path for any of the pieces to land on inhabited
areas.

The purposes of the destruct charges are (a) to absolutely and finally
terminate all rocket thrust, eliminating the possibility of the thing
going even farther astray, and (b) to disperse large masses of fuel,
minimizing explosion hazards.  Inert falling debris is not an issue;
look at the size of some of the SRB fragments pictured in the Rogers
Commission report. 
-- 
If we feared danger, mankind would never           |       Henry Spencer
go to space.                  --Ellison S. Onizuka |   henry@zoo.toronto.edu