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starship-design: Re: Re: regarding fuel expenditures
In a message dated 11/13/97 1:09:16 AM, you wrote:
> Thanks for your response on the matter <grin>. I have always enjoyed
>science fiction for two reasons. The first is that it is entertaining,
>and the second is that some of the speculative stuff winds up becoming
>fact given enough time.
> If you ever get a change, and feel like taking the time and effort
>(which I suspect is in short supply <grin>), take a look at GURPS VEHICLES
>II, which is a set of comprehensive rules for approximating vehicles past,
>present, and future. There are obvious "problems" and such, but for the
>most part, it makes a person think a little. Recently, I began to think
>about what the interstellar probe might be like some 100 years of so into
>the future. Using GURPS VEHICLES, I postulated a maglev like structure
>built upon the moon, or perhaps free floating in orbit.
> In any case, the idea was to launch the device towards the earth, and
>from there, towards the sun. The maglev launcher would launch a rocket
>assembly towards the sun such that the "rocket booster" wouldn't actually
>fire until the probe was near the hyperbola portion of it's "free fall
>towards the sun". The rocket engine would insure that it went into a
>hyperbolic orbit. While close to the sun, the separated assemblies (ie
>the rocket was exhausted and a small modest booster charge separated the
>payload from the booster) would go their own way, with the payload
>automatically spreading it's solar sails. Using the solar sails as a
>further boost, the probe would accellerate to faster speeds.
> My biggest question about the above mentioned "concept" is just how
>close could a payload come to the sun and not be damaged?
> The other thing is, I never actually "designed" the payload system nor
>the booster system to see what the "imaginary" spaceprobe's top speed
>could be leaving the system.
You really don't need to do the sligshot manuvers around Earth and the Sun.
A star Ship needs such powerfull engines, and has to boost to such high
speeds, that the gains from these manuvers are a joke.
How close a probe could get to the sun depends on what kind of
shielding/cooling system it uses, and the amount of time it stays there, so
their no simple answer.
> On a related note: by chance, do you or anyone on your discussion list,
>know how to calculate proper motion with respect to stars? I downloaded a
>50 meg hipparcos file some time back, and it has two entries for proper
>motion. They look to be the same format as declination and right
>ascention. I got the formula for converting right ascention and
>declination (along with the parallax) into cartesian co-ordinates. What I
>would like to be able to do, is create, using TRUE BASIC, a program that
>will calculate not only the x,y,z co-ordinates, but also where those stars
>will be 50, 100, or 500 years from now. Best of all, I can then begin to
>account for other factors such as the fact that a ship leaving a planet
>has the velocity of the planet plus or minus it's accelleration (dependant
>upon what direction the accelleration vector was aimed) along with the
>velocity of the star that the ship is leaving from. Of course, this could
>work against the ship's favor if you have to overcome the star's velocity
>before you can accellerate towards a star that your sun is moving away
It takes thousands of years for stars to move visibly in the sky. So as far
as a starship is concerned you can assume the possition relative to our sun
> What I would really "love" to do, is create some form of random Stellar
>system generation program that would "accrete" the formation of the
>system, calculate the planetary density, radius, and so forth. Then, if I
>could get a few realistic formulas regarding formation of planets and so
>on, I could create a program that would simulate the universe within a set
>"distance" of earth, and allow people to interact with it as though they
>were "exploring" the universe. It would take into account the fantasy
>Faster than light drives, along with some of the more realistic Slower
>than light drives.
You might be able to find such programs as shareware somewhere. Can't think
of where of hand though.
> Well, I have bent your ears enough, and I am probably boring you to
>tears. Any help you could send my way would be greatly appreciated.
> Respectfully yours,
Hop the above helps.