How to Write About Long Distance Space Travel?

Mirannan

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How about this? Use an Orion nuclear pulse drive to get up to operating speed - and then start up the Bussard fusion ramjet. Incidentally, at least one design uses at least some onboard fuel for the latter.

More explanation: The Bussard system relies on taking in interstellar hydrogen as fuel. Unfortunately, most feasible designs using hydrogen use only deuterium - which is a rare component of hydrogen in general. However, the proton/B11 reaction can use the commoner form of hydrogen (just a proton) as one of the fuels.

One might also have an onboard supply of liquid hydrogen for the initial boost phase, if you like, along with the boron supply, and ditch the Orion.

The crew? Well, some form of high-tech aging reduction might be attractive here - maybe based on nanotech.

This thing would be rather spectacular. First of all, there is the huge magnetic scoop at the front - which probably glows quite brightly, as there is going to be gas smashing into it at a significant fraction of c. And, of course, the exhaust which is essentially a stream of hundred-million-degree plasma.

Oh, one more thing: Remember the Kzinti Lesson!
 

Al Jackson

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How about this? Use an Orion nuclear pulse drive to get up to operating speed - and then start up the Bussard fusion ramjet. Incidentally, at least one design uses at least some onboard fuel for the latter.

More explanation: The Bussard system relies on taking in interstellar hydrogen as fuel. Unfortunately, most feasible designs using hydrogen use only deuterium - which is a rare component of hydrogen in general. However, the proton/B11 reaction can use the commoner form of hydrogen (just a proton) as one of the fuels.

One might also have an onboard supply of liquid hydrogen for the initial boost phase, if you like, along with the boron supply, and ditch the Orion.

The crew? Well, some form of high-tech aging reduction might be attractive here - maybe based on nanotech.

This thing would be rather spectacular. First of all, there is the huge magnetic scoop at the front - which probably glows quite brightly, as there is going to be gas smashing into it at a significant fraction of c. And, of course, the exhaust which is essentially a stream of hundred-million-degree plasma.

Oh, one more thing: Remember the Kzinti Lesson!
Indeed the Bussard Ram does need an initial boost speed, but it is only about .00005 c.
Bussard's original paper is here:
http://www.askmar.com/Robert Bussard/Galactic Matter and Interstellar Flight.pdf

It is possible to mitigate the small fusion cross section for hydrogen by bringing along some Carbon
and using the catalytic cycle CNO. See paper here:
http://www.askmar.com/Robert Bussard/Catalytic Nuclear Ramjet.pdf

There are three type of interstellar rams, I have written about such here :

https://www.lpi.usra.edu/lpi/contribution_docs/LPI-001977.pdf?fbclid=IwAR1PHo5An5ad76PjM0QQLx0K9NzRgNQ3VlW8DcnGNJ7EZyE6WI6Gitv5l3Y
 

J.D. Robinson

SFF writer
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I’ve often found myself referring to a great “space travel calculator” (I’m not yet allowed to post links, but it’s the first result that comes up when you search that term). I’m barely intelligent enough to use it myself, but I did manage to get myself to the Kuiper belt in ~33 days in a plausible, but nonspecific way (my story is about the people, and what do they know from star drives anyway?).
 

J Riff

The Ants are my friends..
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Thing is - termites can actually chew through stuff, like an entire set of
baseball cards, 300 or more. They leave a termite-shaped hole through all
the cards. Worms don't generally have the sticktoitiveness to do that, so they probably aren't much good at space travel either.
btw- The planet Termight, the hollow 'traffic planet' from the comic series Nemesis, has a great interstellar highway which departs Earth for various
Milky Way destinations, - just don't get in the wrong exit lane.
 

Mirannan

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Joined
Jan 20, 2013
Messages
1,773
Indeed the Bussard Ram does need an initial boost speed, but it is only about .00005 c.
Bussard's original paper is here:
http://www.askmar.com/Robert Bussard/Galactic Matter and Interstellar Flight.pdf

It is possible to mitigate the small fusion cross section for hydrogen by bringing along some Carbon
and using the catalytic cycle CNO. See paper here:
http://www.askmar.com/Robert Bussard/Catalytic Nuclear Ramjet.pdf

There are three type of interstellar rams, I have written about such here :

https://www.lpi.usra.edu/lpi/contribution_docs/LPI-001977.pdf?fbclid=IwAR1PHo5An5ad76PjM0QQLx0K9NzRgNQ3VlW8DcnGNJ7EZyE6WI6Gitv5l3Y
Nice. I offer a fourth version, similar to the RAR, in which the proton-energy problem is at least partially solved by using the relative velocity of interstellar protons to substitute for the high temperature usually used for fusion. Simply put (very simply, I'm pretty much a layman here) divert part of the incoming stream of protons into a reaction chamber which is continuously filled with a boron plasma. The resulting reaction, p/B11, creates three alphas and there are very few side reactions. The whole thing. therefore, is pretty much aneutronic; nice for anyone who ever has to work on the engine! It's also very efficient in terms of extracting energy.

This would, of course, require an onboard supply of boron, but it has a few advantages over the straight hydrogen fusion reaction. The unused portion of the incoming stream could be used for reaction mass, and as reaction mass is always the limiting factor...

BTW, the speed needed for the incoming energy to be roughly equivalent to 100 million K (about what p/B11 needs) is around 1580 km/s if using the mean. Which is quite high, but still only about 0.005c.

For the initial boost phase, either use Orion or perhaps the same reactor (different settings, obviously) with a feed of both reactants. I would suggest something like decaborane B10H14; for reaction mass at this stage, something easy to store like water would be fine. :)
 

Al Jackson

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Jul 28, 2018
Messages
535
One should note antimatter. My guess is that 200 years in the future there will be antimatter factories making grams of the stuff. Tell ya, once you have that there are all kinds of propulsion systems that are 'hot'!
Antimatter augmented propulsion for solar system travel is the cat's meow! It is expensive to make but once you have it only a dab will to ya! (Below the factory at CERN.)

Antimatter-catalyzed nuclear pulse propulsion - Wikipedia

Wayback Machine

The Evolution of Antimatter Propulsion

http://www.giovannivulpetti.eu/wp-content/uploads/2014/11/Multiple-Propulsion-Concept-JBIS-1990.pdf
 

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L D Warne

amuteforamuse
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I'm with the camp that says you don't really need to tell me it isn't part of the plot.

However, I do like the idea of star / asteroid hopping. You could have a system of asteroids that revolve throughout the galaxy where you can fly to, land on, and then let it take you close to where you need to go before launching back off it again.

For the purpose of your story, you could spend the time flying to, and flying away from the asteroid as convenient plot time (they could go into stasis when settled on the rock itself). This would also bring in the ideas of hops as you can jump from asteroid to asteroid as they pass. This could all be managed via something akin to a Galaxian Underground map.
 

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