Re: starship-design: my $0.02 (finally)

["L. Clayton Parker" <lparker@cacaphony.net>]

Hi Kelly,

I spent a few minutes talking to some physicists about this the other day
(I'm an engineer). They managed to explain to me what it was and the
difficulties inherent in tapping it. They all agreed that it would be a
marvelous source of energy if it could be tapped, but as you pointed out,
finding something colder (less excited) than 3 degrees is not going to be
easy and without a gradient there would be no "spontaneous" emission of
energy. Then there is still the problem of converting it into usable form.

I still think there has to be another source of external energy that can be
tapped, harnessed or otherwise utilized for propulsion. The problem with
all of the known methods of propulsion is that they require enormous
amounts of energy to accelerate a starship to near light speed. In most
cases this amount is so large that there is no reasonable chance that we
can carry sufficient fuel or reaction mass to provide it directly.

Since most of the discussion so far has revolved around specific
technologies for GETTING THERE, I thought some consideration of general
engineering design philosophies might be in order. Here are just a few of
the key things to consider:

1)	Minimum acceleration of 10 m/sec - Anything less would take too long to
get there and expose 	the crew to a host of side effects. This simplifies
design of the ship and eliminates the need 	for spinning habitat rings etc.
More would be better, who knows what might come up.

2)	On board reaction mass must be either sufficient for the ROUNDTRIP or
easily replaceable with on 	board resources. Don't forget a safety margin
here also.

3)	Engineering of the all systems (command, control, communications,
environmental and 	propulsion) should be sufficiently simple to permit
repairs and maintenance by the crew during the 	mission, or self repair
ability should be built in (preferably both).

4)	The propulsion system must be rugged enough to withstand continuous
operation without major 	overhaul or replacement for a period equal to at
least two and a half to three times the duration of 	the voyage. (Note that
this almost automatically excludes most current technologies.)

5)	Manned exploratory missions must be roundtrip, colonization missions can
be considered one 	way for purposes of design. But the mass of a colony
ship will be corespondingly greater requiring 	an even more robust design.

These are just some of the things that need to be considered prior to
selecting a propulsion technology or method. Some methods are just plain
impractical because they would never last through the trip, others fail to
meet additional requirements. If I have duplicated previous conversations,
please excuse this but I think it is more important at this date to define
requirements before examining the technologies current or hypothesized that
might fulfill them. If anybody has any additional thoughts or comments
regarding things they think may be important in defining engineering
requirements please feel free to post them.

L. Parker