# [amsat-bb] Re: Since We Are Off Topic Somewhat....

Auke de Jong, VE6PWN sparkycivic at shaw.ca
Fri Feb 15 01:36:58 PST 2008

```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.

http://en.wikipedia.org/wiki/Kinetic_energy is worded, relative to this
discussion!

Auke,
VE6PWN

----- Original Message -----
From: "Edward Cole" <kl7uw at acsalaska.net>
To: "Jim Jerzycke" <kq6ea at pacbell.net>; "Joe" <nss at mwt.net>; "'AMSAT-BB'"
<amsat-bb at 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).
>

>

```