Deep Impact 0079 (Was: Gundam Fleet Composition Examples)
Fri, 08 Jan 1999 19:26:32 -0800

At 23:33 1/7/99 -0700, you wrote:
> What I mean is that the hypersonic shockwave from the 'bow' of the 30-km
>colony as it slams into the Earth will shoot back through the colony and
>may actually cause the 'tail' of the colony itself to explode while it's
>still high in the atmosphere!

That may be what happened during Operation British. The Iffish Island
colony that was dropped from Side 5 (L1 during the One Year War, moved to
L4 some time prior to 0087) toward Jaburo broke up in the atmosphere,
scattering several large pieces across North America before about half of
it hit Sydney.

> No, you're thinking of simply 'dropping' an object from a high altitude,
>which is incorrect if it's in an _orbit_. The potential energy of the high
>altitude orbit is dissippated by whatever mechanism (thrusters/nukes/etc)
>is used to slow down the object, effectively reducing its energy and
>gradually dropping its orbit.

Well, the colony was guided toward its target, which may have required some
of the energy to be dissipated to achieve the desired trajectory, but
essentially a colony/asteroid drop is no different than any other meteoric
impact. The minimum velocity is going to be about Mach 11, median about
Mach 18, maximum about Mach 25.


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