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

[Kelly St <KellySt@aol.com>]

In a message dated 1/3/98 12:56:45 PM, TLG.van.der.Linden@tip.nl wrote:

>Hello Kelly,

Hi Tim,

>>>It has to be tough, but not into extremes, since backups are available or
>>>will be shortly. I'd guess that if military cars had to be made more
>>>reliable, they should not use air-pressured tires. Chances of a car getting
>>>stranded by a punctured tire on rough terrain seem to be rather high.
>>>BTW Many succesful explorers from the past used equipment that they could
>>>repair or rebuild themselves without outside help. Several expedition
>>>leaders designed equipment with that criteriom themselves before they went
>>>exploring.
>>
>>True but unlike explorers of the past, interstellar explorers would be able
to
>>carry enough to fix things that are as sophisticated as they need.  We'ld
>>probably need to accept that the exploration gear will only last a few
years,
>>archive the data, and make the ship systemsm durable enough to get back.
>
>Explorers of the past could haul large amounts too, however it hindered
>their progress, often too much to reach their goal.
>We may be able to carry enough to fix sophisticated equipment, but it likely
>would increase ship weight (and crew) far beyond what would be the minimum
>for a succesful mission.

Hard to answer without a very detailed analysis of the stuff we'ld be carring,
and what we'ld need to keep runing.  Rough guess, longer the mission, the less
that will be working.  However, if its something that is really needed, we'ld
be forced to carry every support systems and suplies nessisary to assure we
could keep 'it' runing.


>>>While some applications may ask for highgrad computing power, many don't
>>>need to. In much electric equipment limits are pushed, something that we
>>>certainly can't trust to do in our starship.
>>>So we should make circuits/chips that have the computing power of x years
>>>back but use the much more precise and reliable technology of today.
>>
>>Given that even 10 year old circuts are generally a 100 times less capable
>>then current systems, that might not be acceptable.  Also its not clear that
>>old design IC's built with new equipment would last especially longer then
>>current designs built on the same equipment.
>
>Well let me give a simple example then: Say you've two gears, in the past
>the quality of steel was rather poor, so they had to be big to have a
>reasonable lifetime. Now we can control the strength of steel much better so
>can make these gears thinner and smaller and still have the same lifetime.
>I'd guess that if we used better steel and kept the same size as in the
>past, then we'd really increase lifetime.
>Indeed the much larger mass of such a gear may not be acceptable, but if it
>means that it will need much less maintenance, thus less crew, thus less
>food, thus a smaller habitat, then I wonder if it really is less acceptable.

Good trade off case.  Thats why I'm assuming the heavy industrial and
structural systems would be over built to allow a long enough service life.
But then gears and metal components are pretty long lived anyway.  Things get
much more brittel with high precision systems, especialy things like
electronics that arn't normally designed to work for decades.


>>>Similar to what Zenon wrote, we shouldn't expect the same luxuries as in
our
>>>homes.
>>
>>The ship is a high tech exploration system.  Computing power isn't a luxury.
>>Any cut in computer sophistication will be a direct impact in the ability of
>>the science teams on the ship to analiae the data the surveyteams on the
>>ground, and the probes, recover.
>
>Well, would todays technology combined with shortlived 2050 technology
>really be too crude for an interstellar exploration mission?
>(The 2050 equipment would be used until it failed and then the old and
>easier to repair technology would be used for further exploration.)

Certainly the systems of most concern (computers, electronics, chemical
systems, etc..) would be unlikely to benifit from using 50 year old versions.
Thou their probably is some way to make custom designs for some systems that
would be more durable then their standard 2050 counterpart.


>>>>The fusion engines are far simpler then standard rocket engines.  I.E. few
>>>>pumps, nozzels, no presure vessels, etc.  I'm not clear what you mean
about
>>>>reflectivity/conductivity.  Certainly a system with the scale your talking
>>>>about wouldn't have its conductivity effected by surface blemishes.  If
its
>>>>a problem, design the system so it will work with the entire surface
>>>>corroded or clean.
>>>
>>>If a fusion engine is so simple, then a fusion power plants should not be
to
>>>hard to build and maintain either. What I've seen from fusion power designs
>>>is that they look pretty complex, more complex than chemical rocket
engines.
>>
>>Power plants would need to be a little more complicated since they need to
>>convert reactor power to electric power.  Also the current designs (ignoring
>>the magnetic tourus systems which are pretty unusable) arn't that
complicated.
>>Even better most of their components are large blocks of materials (lenses
and
>>photo multipliers for laser fusion, thick conductor bands for magnetic and
>>electrostatis control systems, heavy metal support structure, etc.).
Compared
>>to a computer core their trivial.
>
>I wasn't comparing with a computer core, but with a chemical propulsion
>system (although I could have been more explicit). I believe that according
>to Lee todays propulsion systems do have a MTBF long enough for a two-way
>mission.
>I wondered whether fusion rockets would have similar reliability, since they
>likely are more complex than their chemical counterparts. And if our rockets
>are pulsed, they may get much more structural stress than chemical rockets
>that as far as I know are continuous.

Chemicalsd do need to deal with presure and vibration.  Hopefully fusion
systms would be less erratic, but if not the levels would need to be kept
similar or the vibration loads could shake the ship up badly.


>Furthermore, while a fusion rocket may not need to turn the heat into
>electricity, it still is comparable with a fusion powerplant, since it too
>has to control the energy flow. It can't just be compared to a H-bomb, which
>can freely expand in all directions and hoped to do as much damage as
possible.
>
>>>>>If an engine part fails, disasterous things will happen. If a
circuitboard
>>>>>fails, it likely can be repaired before lifetreathening situations arise.
>>>>
>>>>That depends un what the circut board controls.  Circut failures can and
do
>>>>kill people rapidly.
>>>
>>>I don't know what kind of circuit failure you mean.
>>
>>Anything that could disrupt the function of the circut.  (Corosion shorting
>>out pathways, capacitors starting to leak, diodes breaking down and not
>>filtering the electron flows, IC chips logic burning out, etc.)
>
>How do these kill people rapidly? I'd expect some authonomous backup systems.

Assuming the backup control signals didn't need to feed through the circut
that died.   ;)


>Timothy