[LINK] Finally up to date on the Shuttle

Frank O'Connor foconno1@bigpond.net.au
Fri, 14 Feb 2003 17:51:42 +1100

Thanks Bernard and Tony,

I am constantly grateful that we have the odd bit of engineering 
talent on the list to explain these sort of things for we neophytes 
... it saves us from falling back on the embarrassing 'Fairies do it' 
argument that I often have to resort to with my unnaturally curious 
nephews and nieces. (Who fall back on the old "He's a senile old 
twit" addendum when I do use the 'fairies' explanation.)


At 4:07 PM +1100 14/2/2003, Bernard Robertson-Dunn wrote:
>Re all this orbital mechanics stuff.
>The dynamics of an orbiting body is a combination of kinetic and potential
>An orbitting body at (say) 500km altitude has a particular velocity. To get
>to an alltitude of 1000km, it has to fire its rockets. Once it gets into
>its higher orbit it is actually going slower than at 500km. The energy from
>the rocket firing has initially been converted kenetic energy but with an
>increase of altitude this changes into potential energy.
>Every orbital altitude equates to a particular velocity (both angular and
>The reason why a body has to decelerate to go into a lower orbit, but
>higher velocity, is because it has excess potential energy. Total energy
>level (KE+PE) needs to be reduced in order to get to a lower orbit. This is
>done initially by reducing the KE. As it moves to a lower orbit the PE
>reduces but the KE increases to a level that was greater than at the higher
>I know that this defies the law of gravity, but, you see, I never studied
>--Bugs Bunny
>Bernard Robertson-Dunn
>Canberra Australia
>Link mailing list