Re: Fwd: LIT e-mail discussion group

[T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden)]

I had to think it over a while, but thanks for reminding:

>One-way
>		* Suicide (explore and die before your time when supplies end)
>		* One-way (Enough supplies are shipped to stay in target system >
until natural death)
>>Pros
>The ship need only be designed for a one time, one way flight.  This limits
>the technical mission risk and requires less resources.

Actually there may be an equal or bigger amount of resources. That depends
on if the crew needs to be larger and if more appliances are needed.
If instead of 1E9 kg of fuel you could bring extra crew and appliances that
would probably make a "colonalization" more probable to succeed.

>Lower information return to Earth due to limited baud rates of interstellar
>communication.

Assuming we are able to create 1E18 Watts I think that bandwidth is minor
problem.

==============================================================================

>Round trip (Crew returns to Earth with ship at mission end.)
>
>>Pros
>Simplest option, and one with little likely hood of public objection.

I'm not sure what you mean with simplest, I think only the part after the
comma is true.

>It obviously avoids the grisly public relations and crew morale problems of
>a one way mission.

Seems to me that you use this twice as a pro in this mission.

>>cons
>Technically more challenging.  Getting a ship to the target starsystem is
>hard enough.  Getting it back would make it harder.  But this must be
>traded off against the added complexity of a ship capable of supporting its
>crew for the rest of their lives.

Indeed, but if we are not able to build a small colony during a one-way
mission than the chances are small that we are able to build a complete
power array for a two-way mission. So this means that all power for the
return mission has to come Earth.

==============================================================================

>Pick up and return by follow on flight

>>cons
>High risk and more complicated.  Multiple ship types, and concerns that the
>first ship might be left stranded.

Also politically less preferable, because the project will take longer and
probably twice the effort.

==============================================================================

>Crew constructs equipment for return flight
>This option come up with light/microwave sail craft, beamed power craft,
>and fuel launcher craft.  The crew would  construct automated duplicates of
>the systems that launched the ship from Sol space.
>
>>Pros
>Would establish launcher facilities in both star systems.  Which could
>allowing faster two way flights with specialized fast light ships.

This assumes that either people stay behind to control and repair the
launcher or that we have AI that is smart enough to keep the thing working
perfectly.
!! This is something we have not discussed before as far as I know !!

>The crew might get back faster with their ship using the constructed
>launcher systems for assistance.

>cons
>If they can't build the equipment, they don't get home.
>
>The construction phase may require so many resources that the first flight
>is devoted just to infrastructure construction.  With little or no
>exploration being done in the first mission.  This obviously would cool
>public interest and slow down the return of productive information.

Again, if we are not able to build a small colony during a one-way mission
than the chances are small that we are able to build a complete power array
for a two-way mission. So this means that all power for the return mission
has to come Earth.
Although a power-array may require less different parts than a colony, the
size it much bigger and it uses the same type of machinery that is required
to build a colony.

Another con is that less time is available for research, unless robots are a
possibility.

==============================================================================

>Multi-step.  (Ship proceeds to other target star after completion of first
>mission, in first starsystem.)
>
>>cons
>Technical feasibility is low since wear and tear on the ship would
>accumulate, dramatically increasing the likelihood of a catastrophic
>failure.
>
>Because of the extremely long flight times with likely technology, the
>mission would take so long as to be undesirable.  At some point the ship
>would be superseded by newer faster ships sent straight out from earth,
>decades after its launch.

Not even undesirable long, but probably too long. Also the conditions should
be the same as a one-way mission and it needs much more energy

==============================================================================

>Multi-generation Succeeding generations of crew continue the mission
>
>>Cons
>The follow on generation(s) in the ship will have no allegiance or
>commitment to the mission or its originators (they, never agreed to
>anything).

When children grow up in a certain environment, they may like it there. So
it may be very likely that they will continue the mission.

>The follow on generations would have no hands-on experience with the
>exploration systems they would be expected to use.  Or for that matter, any
>experience with planets and starsystems.

The could be trained just like the initial crew was, the ships computers
will have a large amount of knowledge and learning tools.


>               technical                 political          Desirability
>             Risk    Feasibility     risk     Feasibility
>-------------------------------------------------------------
>One-way      med-low  Medium         Ex-high    Nil          Low
>Round trip   medium   medium         low        High         high
>Pick-up      Med-high medium         medium     medium       medium
>Construct ret high    med-high       medium     medium       medium
>Multi-step   Ex-High. med-low        low        Medium       medium
>Multi-gen    Ex-high  Low            high       medium       low
>Hibernation  high     Low            medium     medium       low

The feasability of a round trip probably depends on the creation of a power
source at TC. I think that if that power source can be created, a colony for
a one-way mission can be build also. That makes the political feasability
much higher. Maybe even higher than a two way mission. I would find it more
exciting to know there people building on a new civilazation than on a back
and forth mission. If the colony could prosper its (political & scientific)
value is much higher than a two way mission.

Multi-step, Multi-gen and hibernation ships all have the same condition(=a
working ship for >40 years) as a one-way mission so I think they should have
the same political feasability.

The difference between constrution-return and round-trip are not clear since
we haven't defined how(=what energy source) the round-trip makes its return.
So its not clear how the differences in feasability are explained.

=============================================================================

>Mission purpose
>---------------------------------
>Colonization of planets or moons

>Isolation from resources.  Ores, energy and raw materials are far harder to
>access on a planet than in space.

If the death-trap could be overcome be medical care, it may be more pleasant
to live on a new (fresh) planet than in a space station.

=============================================================================

>propulsion systems
>---------------------------------
>Fusion feed from internal fuel sources.
>Staged fusion ship

I think you shouldn't look at staging the "classical" way. Why not add
hundreds of the same kind of engines and throw them away when not needed any
more. Making many engines of the same type is probably cheaper than a few
that differ in size. Another advantage is that when one becomes defect it's
not a big deal (unless it is an error that each engine has).

In fact this is just a ship with say 1000 stages.

A problem with staging is that you throw away your ship, this makes a
two-way mission much harder!

>Anti-matter
>Can be destroyed to create tremendous amounts of energy.  Releases over a
>hundred times as much power per pound of fuel as a fusion reaction.
>
>Unfortunately, though it releases more power, this power is harder to
>directly use to power the ship.

This is not certain, the ideas I stated some time ago are only a few and
were considered as most preferred though less easy methods. There does not
have to be a real difference between a fusion or an anti-matter powered
ship. Both can be used as heat-energy sources to accelerate reaction mass.

>It is however far more dangerous to
>handle.  If we could synthesize the thousands of tons of antimatter this
>would take.  It would have the potential of exploding with a force of
>hundreds of millions of H-bombs.

This explosion can only happen if there is an equal amount of matter nearby.
I think it may be possible to keep the anti-matter far enough away (in a
large torus for example) Of course even when a minor amount of anti-matter
is "spilled" the ship is likely not to reach its final goal (but does not
have to explode). So while your argument is not completly right, the idea
is. But of course when a major engine of the ship stops working indefinately
this may also be the case.

>Future tech
>
>The engineering and science we have now and assume we will have in the
>future will change.  Fusion, fission, relativity, quantum mechanics, and a
>host of other basics of current physics; all were discovered within the
>last hundred years.  We can conservatively expect physics to have changed
>far more in the next hundred years, then it did in the last hundred years.
>What technologies that age will have on hand are impossible to guess.  They
>could have matter conversion, hyperlight drives, new understandings of
>inertia and kinetic energy, or all those and far more.  Any of these would
>dramatically effect our ability to travel between the stars.  So even
>though we can't come up with any practical ideas for exploring the stars
>now, we can be sure our descendants will find it far easier than we
>imagine.

FTL is a principle that has been withstanding many experiments to unprove
it. Chances are small that FTL will become possible in the next century (if
at all).

==========================================================================

A possible disavantage for a two way trip is that the crew has to live a
long time in a ship. If it is a disadvantage depends on the size of the
ship, if this is a disadvantage for a one way mission depends on the
possibility to extend the ship when at TC.

Timothy