Re: Re: Re: starship-design: One way (again...)

[Kelly St <KellySt@aol.com>]

In a message dated 12/6/97 12:08:42 PM, kuo@bit.csc.lsu.edu wrote:

>KellySt@aol.com wrote:
>>In a message dated 12/4/97 3:09:55 PM, kuo@bit.csc.lsu.edu wrote:
>
>>>>>> I disagree.  If I were offered the chance to fly on a 1 way mission
>>>>>> to the Alpha Centauri systems at .2c (where I'd then spend the rest
>>>>>> of my life), I for one would jump at it. I'm sure there are many
>>>>>> others who'd be just as excited to do so.
>
>>>It's not a suicide mission.  Suicide is purposefully dying prematurely.
>>>With a couple hundred years of life support supplies, there's no
>>>inherent reason why the crew would die prematurely.
>
>>Actually even if you had a couple hundred years of suplies its unlikely the
>>ship could stay functional for more then a few decades.
>
>Even if that were the case, it's not _certain_ to fail.  At least
>in American culture, this is a critical difference.  It's why we
>were willing to enlist in 2 dozen bombing mission tours but never
>even considered Kamikaze missions.

It is statistically certain to fail.  I.E. if you are asking a systems to work
longer then the average mean time to failure of its parts, it will fail
without the replacement of those parts.  If the parts are primary structure
(remember we'll be shaving weight margines to get the thing flying) you need
major shipyard facilities.


>>Normal systems on that scale usually burn out after 40-50 years.
>>Given the lack of replacement parts (stored parts also don't last
>>forever),
>
>They don't have to last forever.  They just have to last several
>decades.

Many can't last a few years on the shelf.

>>and the fact the crew would also be wearing out
>
>Why would the crew be wearing out?  We'd be getting old after a
>while, but at that point it would be getting less and less
>important to have the equipment last much longer.

It has to keep working for the crew to keep living.  If it needs repair NOW,
you can't just hope it woun't fail for a decade or two for the last crewman to
die.  It almost certainly will fail in months to years.


>>(thus lowering their ability toservice the craft), the ship
>>probably wouldn't last as long as the crew theoretically could.  Humm.. then
>>again the crew isn't going to have access to top of the line medical
>>facilities (or non aging medical personel) so their life expectancy would be
>>shortened too.
>
>The life expectancy would indeed be greatly reduced compared to
>staying at home.  Besides the lack of medical facilities, there's
>the issue of improvements in technology back at home.
>
>The worst case possibility is if someone develops a "fountain of youth
>pill", which can be manufactured on the ship.  Then the crew would
>be guaranteed to die due to lack of supplies and/or ship failure.
>
>But none of this is _guaranteed_.  So it's not a suicide mission.

Your sending people out to to a decade or two of work (at most until the
exploration gear become unservicable) and then sit in the deralic ship until
they die.  

Thats effectivly a suicide mission.  I know a few folks in this group
disagree, or don't care, but it still would meen no government on earth could
get permision for such a mission.  I.E. your throwing away a crew for no
critical reason.  Specifically your doing it to save money, which is really
not going to sell.


>>>As for 2-way vs. 1-way, I gave as an example a .2c cruise speed.
>>>A 2-way mission at .1c would take at least 80 years to get there
>>>and back!  With current human lifespans, that sounds to me a
>>>hell of a lot worse than going one way in 20 years and then spending
>>>the next half century or so basking in the warmth of alien suns.
>
>>I don't follow the numbers.  First you state a .2c cruse speed vs a .1.  Why
>>would a 2 way mission use a slower ship?
>
>Because a 1 way mission can go at 1/2 delta-v of a rocket, while a
>2 way mission can only go at 1/4 delta-v.  Alternatively, if beams
>are used for the acceleration run (and the deceleration run of the
>return journey), the 1 way mission can go at 100% delta-v, while
>the 2 way mission can only go at 50% delta-v.

The delta-v potential of a ship is related to the fuel mass ratios.  The fuel
mass ratios are exponetial, not linear.  I.E. a ship that needs to accelerate
and decelerat with onboard fuel (Li-6 fusion fuel) needs 400 times the fuel
load of one that just needs to accelerat or decelerate not both.  Or for a 2
way unrefueled mission it would need 400^3 as much fuel.


>>Oh, and since your stuck in the same ship parked there, or on the flight
back
>>(no you can't spend you years on an alien beach), I can't see how parked
would
>>be prefereable.
>
>Alpha Centauri includes a binary system.  It would indeed take decades
>to study this system, which is very different from our own.  Being
>on site means being able to rig up whatever equipment is needed to
>make whatever observations are desired (a 2 way mission could leave
>behind unmanned probes, but they'd have more limited capabilities and
>wouldn't be able to react to scientific advances prompting new
>observations as quickly).
>
>Stars aren't just big balls of fire.  Even studying our own Sun is
>a lifetime career!

Without tools?  The systems will wear out and your light years from the
manufacturing infastructure needed to keep all the stuff working.  As a wrough
guess I'ld expect the transport shuttles and such to burn out in under 20
years, and the main ship sensors and systems to be maybe good for 40.  Past
that your need to strip those systems for pars to regulate life support,
medical, etc..

I.E. you not talking about spending your life studing the starsystem.  Most of
the time your just going to be working to keep the last of the ship (and
yourselves) alive.

>-- 
>    _____     Isaac Kuo 

Kelly