Hello!
At the moment, I'm busy writing a non-fiction book on martial arts - my first. To take a break and keep the writing hormones going, I on occasion try my hand at what I really want to write, S-F. Of course, I'm not very good at it, hence no Hugo awards yet. Or Nebulae. Or sales.

It'd probably help if I actually submitted something, of course.

It'd probably help if I actually finished something of course.

Anyhoo, the other night I came up with a grand idea for a storyline - a world to set stories in. I thought I'd put it up here - I'm just curious as to whether or not - from a realistic astronomy and engineering perspective - such a thing would be possible. (Which is why I'm putting it up in the General Astronomy forum, and not the community.)

Side note: My writing tends toward the off-beat and eccentric, even in non-fiction. Living on a steady diet of Douglas Adams, Terry Pratchett and David Eddings tends to do that, methinks. In short, I don't like taking things too seriously - hence the focus of this idea. Rather than describe the whole thing to you; I'll just copy out the introduction I wrote - please pick apart the science from there.

(Not, of course, that the science means a whole lot in what is basically an exploration of weirdness, but I was just curious to see whether such a thing could be possible.)

It's called the Jovian Express:

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The Jovian Express

Imagine for a moment the greatest engineering project of all time.
Imagine a ferry service with a route hundreds of millions of kilometers in length.
Imagine a series of twenty four comets plucked from the Oort cloud and sent diving into the Solar System on highly elliptical four-year orbits, precisely calculated to pass within one million kilometers of Earth.
Imagine carving a station into each of these comets, providing accomodation, food, fuel, oxygen and water for ten thousand people.
Imagine a ship taking off from Earth and landing on one such comet. Rather than brave the incredible distance alone using up supplies, this ship could ride out the long trip in comfort and safety, until it reaches a point where it may take off and fly to its destination.

Imagine that...because someone did imagine it. And built it.

D.H. Regan built the Jovian Express because he could. He had the money, the resources, the political clout and above all the starry-eyed dream of easy planetary travel for Man. He intended the Express to be a vast, magnificent fleet of ferries taking colonists, scientists, explorers and dreamers to the far corners of the Solar System.

Now imagine the type of person deluded enough, dreamy enough, crazy enough or just plain dumb enough to volunteer to work on a station carved into a flying snowball for four years on basic wages, and you'll have a pretty good idea of what the Jovian Express turned into.
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I know - bloody silly idea; that's kinda the point.
From a science perspective, whaddaya think?

Cheers!

Sounds a bit like Heart of the Comet (1986) by David Brin & Gregory Benford. [review]

I am not a rocket scientist, but it seems to me that the acts of slowing down to land, and then taking off from the comets (not to mention the enormous initial costs of changing the comets' orbits in the first place) would cost more fuel than just riding out the trips in the space ships themselves.

What exactly do the comets save you in terms of resources? If there were some minable fuel on/in the comets then I could see the advantages of using them as a gas station, but I see no advantage of simply using them as a "space ship ferry".

Hey; like I said, it's silly.
No sillier than a pancake-skaped world riding on the backs of four elephants standing on the shell of a turtle flying through space...but then; Pratchett can get away with that due to his phenomenal writing skill.

The basic idea is that the Express is made up of a chain of 24 comets; knocked out of their orbits in the Oort cloud and sent in to pass within a million kilometers of earth, passing near certain planets on their way out. (For instance; the one passing mid-February will be going past Saturn, while the one that comes at the first of June will be aiming for Mars and on to Pluto. However the orbits line up at the time.) Once each comet reaches its apogee, course corrections and a new burn are made to send it in another helpful orbit.

Now - why?

OK; this is where things get admittedly really silly. Comets are basically big snowballs. They are therefore huge concentrations of water ice. Water = hydrogen, oxygen. Other bits on the comet include carbon and nitrogen. Thus from the comet you get food, water, air, fuel. Also space and recreational facilities from the station, as well as engineering and science labs.
So the idea is; as described earlier: A ship leaves on a routine (?) flight to Uranus. It departs from LEO and flies to the comet, which has been plated to avoid creating the tail. (Ummm - yeah. OK; so I fudged that one - haven't quite decided on that; I can come up with a few funny twists on getting through the tail, but haven't quite decided yet.) Anywhich; said vessel flies to and docks with said station and is winched inside. Crew and passengers get off, and enjoy the Luxury And Comfort Of Cruising the Solar System in Peace and Style. (As it says in the Express's brochure. What it actually means of course is really expensive bad food, bored-to-tears-and-thus-surly crews, NO view except from an observation blister which tends to produce extreme spacesickness, and a temperature which never seems to get much over freezing.)

...ahem.

While on (in?) the station, the ship is refuelled and maintained, crew and passengers are...entertained (for a year and a half - most people working on passenger liners can't stand theirpassengers for more than a week at a time. Heh heh - guess what?) .

Once the Express reaches the point where the ship can launch and easily intercept their destination, the crew and passengers (thankfully) board, it lifts off and get the Hell away from the comet as fast as it possibly can.

At which time the station crew celebrate like mad for a few days and go back to being bored, homesick and stir-crazy.

Which sounds like a pretty fun environment to make up short stories.

That's a pretty short orbital period. Where are they supposed to be going? You might be able to get out to some main belt asteroids in around this time frame. If you are talking outer solar system, it will be much longer. And is this supposed to reach the same target repeatedly or just once?

There is a concept called the "orbital cycler" that has been suggested for Earth Mars travel: A space station like spacecraft in an elliptical orbit between Earth and Mars orbit. A smaller spacecraft would fly between Earth (or Mars) and the cycler, and this may reduce fuel/mass requirements if there is heavy traffic. The key issue is flight time. It isn't enough to go between orbits - you also need to be close to each planet at the proper time. That makes for long flight time even for Earth and Mars.

Here's a site with a graphic of asteroid cyclers:

http://www.clowder.net/hop/railroad/railroad.html

[edited to add - I wrote this before seeing your last entry. Anyway, travel time past Jupiter will be reaching into decades.]

Now that's interesting - raises some possibilities for this little fantasy. The orbital period on the other hand.... Hmm...let me think about this a minute. :-k

OK, two possibilities: 1) Somehow speed up the comet so it travels faster. Still taking a whopping long time to get anywhere, but less than decades. I'm kinda attached to my 4-5 year time frame; it provides all sorts of opportunities for freakish characters. I know this won't really work; you need to lose all that speed as well. 2) make the final destination one or two specific places - Mars, and one or two colonies built inside the asteroid belt.
:-k
Actually, that might work - the reason the Express started in the first place would be the Mars colonization/ Asteroid mining boom - besides being a dreamer; Regan knew damn well how cornering the transportation market could rake in megabucks.

OK; the modification thus: 12 comets passing between Earth, Mars and 3 deep-space mining colonies in the Asteroid belt. (The problem of course is that it couldn't be the 'Jovian Express' anymore.) :roll: Ermm - I'll need another name.
:-k :-k :-k

But the mere process of landing and taking off from the comet would disrupt the orbit.

Remember the law of the conservation of Momentum [-X

There would be serious objection on the grounds that a rogue comet from this conveyor belt could vear off and hit the Earth.

Plus how long would it take to get out to the Ort cloud in the first place.

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Moderations in purple

Fame, glory adventure, a cyber warrior craves not these things.

Some thruster fire should handle that. Besides, you would still be more docking with than landing on an asteroid.

By The Daily Mail and who cares what they think?

About a billion years.

The only difference is that one way you use some kind of latching mechanism, the only way you use gravity. Conservation of momentum still applies.

The way to solve this would be to have as much go from Earth to Jupiter as go from Jupiter to Earth.

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Freedom For Fission A breath of fresh Iodine-131

Jovian Express? Snowballs? Will Tom Hanks be playing almost all of the characters?

Serious: Don't, whatever you do, go to the Oort Cloud. It is a ridiculously long way away - on the order of a light year. Enough comets predictably come through the inner solar system to supply your Express. Once a comet has been located, a robotic spacecraft is sent there with some super-engine (perhaps a small fusion reactor) that can produce large amounts of energy. It uses that energy to boil ice from the comet, producing a rocket engine that brings the comet close to the Earth. Here a set of larger engines are fitted, along with the habitation module. Then you can blast off at high speed to Jupiter, using the entire comet as your fuel tank.

I'd advise you to have a conventional space-station habitat attached to your comet: I doubt that comets are solid enough to build airtight tunnels inside (unlike asteroids). You could still have relative luxury: with all the mass of the comet as fuel, you can have a large habitat.

Hey; thanks all for the help, friends.
No question; the science involved in this little story is about as solid as a sieve - that's nuthin'. Wait 'till you see what I do with the bloody things! (I've been having fun writing plot outlines and character bios.)

Dave: Yeah; I picked the Oort as a possible site for grabbing comets simply because there's a lot of 'em out there. Of course; it's a little on the far side, but really I don't have to go into detail about how Our Heros (or the Corporation that emplys them) snagged the bloody snowballs in the first place. You idea is much better than mine; with all sorts of interesting storyline ideas.

As for your second point; actually I already thought of that. I didn't build the station inside the comet in spite of the instability; I built them inside because of it. The basic idea is that one of the less attractive features of the Express is that it never seems to get much over freezing; except occasionally (with a small...er...surcharge) in private passenger quarters; which are located near the center of the station. If it gets too warm ant that heat is transferred to the station's exterior well...
Picture a snow-globe in reverse. Shake it up; and the snow says more or less where it is while the little plastic town bounces around. It's called "Breakaway" and a major risk to the station at any time - one of the main reasons that one of the most prestigious jobs on board is that of Refrigeration Mechanic.

The first story should by done by Sunday. I'll put a link to it up here for people to read, if they want.

Sorry; I'm just having fun writing something as totally anti-non-fiction as I possibly can.