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Re: Since We Are Off Topic Somewhat....



This might be excessively basic, but wouldn't the heat energy of the 
friction in re-entry be roughly equivalent to the energy from the engines 
which put the craft up there in the first place?  This doesn't include the 
de-orbit burn, obviously, but since the shuttle has a lot of mass, there 
will be more time spent at high velocity dragging against the atmosphere, 
than a relatively small satellite which weighs much less mass, given the 
same descent path because of it's higher intertia(Kinetic Energy).

Also, since the shuttle enters at a sharp angle, the rate of deceleration 
would be higher since power=forceXdistance.  If a satellite enters at a slow 
angle(typical), then the temperature of the heat generated from friction 
would be much lower, for much longer and pieces of the craft might have 
slightly better chances of not vaporizing.

I like the way that the first paragraph in this page: 
http://en.wikipedia.org/wiki/Kinetic_energy is worded, relative to this 
discussion!

Auke,
VE6PWN

----- Original Message ----- 
From: "Edward Cole" <kl7uw@acsalaska.net>
To: "Jim Jerzycke" <kq6ea@pacbell.net>; "Joe" <nss@mwt.net>; "'AMSAT-BB'" 
<amsat-bb@amsat.org>
Sent: Friday, February 15, 2008 1:24 AM
Subject: [amsat-bb] Re: Since We Are Off Topic Somewhat....


> Also remember that during launch the space shuttle is facing directly
> into the direction of travel thus presenting the lowest drag (and
> least friction).  During re-entry the space shuttle lifts its nose a
> bit to expose more area of the underside of the craft to produce more
> drag.  This increases friction.  As the shuttle descends, air density
> increases which increases friction.  The shuttle slows due to this
> friction.  The decent path is a smaller rate of decent (lower angle)
> than launch which is nearly vertical at first.  This gives more time
> for slowing due to atmospheric friction.  All this produces very high
> temperatures.  Too steep a decent would increase temperatures beyond
> what the tiles on the skin of the shuttle can withstand and the
> shuttle would burn up just like a meteor.  Hope this helps understanding.
>
> Ed (just an old retired NASA engineer - not quite rocket scientist).
>

> 

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