Re: Re: Re: starship-design: What is safest?

[kuo@bit.csc.lsu.edu (Isaac Kuo)]

Kelly St wrote:
>In a message dated 12/11/97 12:02:40 AM, kuo@bit.csc.lsu.edu wrote:
>>Kelly St wrote:
>>>I deliberately refure to them as "suicide" missions for two reason.
>>>First to emphasis that that is how they will be perceved as by the
>>>public.

>>Only if the public is like you (and remains like you).  The public
>>may have a different attitude.

>I spent 15 years in NASA and few more in other such things.  This is an issue
>with a lot of study by such folks.  You do NOT, EVER, suggest astronuats or
>crew are expendable, or ever put in a situation where every effort to support
>their safe return wasn't taken.  The political firestorm from violating those
>rules is intense, and one sided.

Okay, but in the case I pose the crew are not expendable--every effort
is put into insuring their safety--and every effort to support their
safe return is taken (there is no way to make a return at all with the
technology available).

>>>Secound because I beleve the odds of outliving the dieing ships
>>>systems decrease exponetially as you significantly extend the
>>>mission length.

>>In order to perform a 2-way mission, you have to double how long
>>it takes to reach the target system, and this is also how much time
>>it takes to get back.

>Proven false on several occasions by several persons here.

No, you always make the assumption that you refuel in system.  The
situation I pose is that of a first mission, which can not refuel
in system.  Even if they could bring with them the necessary
equipment to do so, they won't have sufficient information about
the target system to reasonably expect it will be possible to
refuel.  Not for a first mission, at least.

Also, I'm talking about a mission to a star system which may not
have any resources with which to refuel at all!

You're using a circular argument if you start off with the assumption
that we need to refuel or we'll never go.  You can't argue that a
2-way mission is the only possibility by starting off with the
assumption that a 2-way mission is the only possibility.

>>In the case of a .2c 1-way mission, the one way mission lasts perhaps
>>60 years (about the time the crew die of old age).  In the case of
>>a .1c 2-way mission (this uses equivalent technology), the mission
>>lasts perhaps 60 years (about the time the crew die of old age).
>>They can't live the 80 years it takes to get there and back.  In
>>the case of a .2c 2-way mission (this uses more advanced technology),
>>the mission lasts perhaps 50 years (10 years in system).

>Far slowrer than an mission suggested by anyone with the possible exception of
>you.

But it's the mission length implied by the technology level I assumed.
I am assuming technology is capable of .2c cruise velocity (e.g. a
.4c delta-v capability with mass ratio of 10,000), and that since
this is a first manned mission to Alpha Centauri it's impossible to
refuel.

Given the proximity of .4c delta-v capability to the theoretical limits
of fusion rockets, it's not implausible that a technological plateau
of that level long enough to justify not waiting for further advances
could occur.
-- 
    _____     Isaac Kuo kuo@bit.csc.lsu.edu http://www.csc.lsu.edu/~kuo
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