[X] My Assistant

[tacitus]

Hi, I've just written the first draft of a science fiction short story and I need little help with the plausibility factor . Since many highly educated people hang out in this forum (flattery will get me everywhere... I hope!) I thought this might be a good place to ask a few questions.

The story is about a colossal creature (think Titan-sized, as in the moon Titan) that lives amongst the stars, travelling from solar system to solar system, hibernating while in between. (Hey, I didn't claim it was original .) I'm not so concerned about the plausibility of such a species evolving as I am about how the creature is powered.

The creature's internal systems are powered (for want of a better word) by a fission reactor, which I think is okay. But its propulsion is powered by the burning of hydrogen and oxygen (i.e. as in rocket fuel) extracted from water - and this is the bit I'm unsure about.

I know hydrogen and oxygen can be extracted from water, and with a colossal nuclear reactor at its core there is enough energy for the creature to do so, but I just don't know how plausible this whole propulsion set up it. (I guess I can live with "unlikely", I just don't want to base the story on something that's "impossible".

An important aspect of the story as it is written is that the creature needs to stock up on its water supply and has to munch on moon-sized objects to do so (think Europa-sized or smaller in this instance). So its critical for the story that water, and the need to replenish its supply of water, plays a very large factor in the creature's life. I know we are talking colossal sizes and amounts of water here, but that's part of the nature of the story.

So, what do you think? Am I on the right track or careening off the rails?

Any help at all would be greatly appreciated.

Thanks,

Mike

[Guest_exobioquest_*]

Well I'm not educated but a several thousand Km wide planet eating space monster that is fusion powered yet is propelled by H2+O2 is like a nuclear submarine propelled by paddles! You got fusion power, just us it to plasmify a propellant (H2O, H2, heck any materially eaten) and vector it out, it should give you many times the specific impulse of H2+O2 combustion. The creature will likely have a preference for hydrogen for its fusion reactor(s) thus planets with water (planets with gaseous hydrogen will likely be too big to eat)

[tacitus]

Well I'm not educated  but a several thousand Km wide planet eating space monster that is fusion powered yet is propelled by H2+O2 is like a nuclear submarine propelled by paddles! You got fusion power, just us it to plasmify a propellant (H2O, H2, heck any materially eaten) and vector it out, it should give you many times the specific impulse of H2+O2 combustion. The creature will likely have a preference for hydrogen for its fusion reactor(s) thus planets with water (planets with gaseous hydrogen will likely be too big to eat)

Good point - but the way the story stands the creature has an internal fission reactor, not fusion. Does that make any difference? (Probably not, I guess). Thanks for the tip.

[ljk4-1]

Have you read Gregory Benford's 2000 SF novel, Eater?

http://www.space.com/sciencefiction/books/eater_000317.html

http://www.sfsite.com/05a/eat80.htm

http://www.scifi.com/sfw/issue152/books.html

http://en.wikipedia.org/wiki/Eater_%28novel%29

And knock my socks off - I just discovered that someone has written a screenplay of the novel and it is online here:

http://www.lasttemplar.com/PDF/EATER.pdf