Writers of the Future submission – or – How to Build a Starship

I pressed submit on Passing in the Night for Writers of the Future late last night.

I’ve got mixed feelings about the story and its prospects, though.  I had a few people read it this week, and got a variety of responses, ranging from “good” to “meh”.  Reading back over it, and taking some late feedback into account, there are definitely a few rough spots in the story.  And maybe it could be faster paced and less technical.  I spent a lot of space in the story describing how the ship works.  I actually wrote the story in order to explore how such a starship might work.

But I enjoyed writing it.  Maybe the contest judges will like it too.  If not, no harm no foul.  I can tweak it and try to submit it elsewhere, or publish it myself.  Someone, somewhere might enjoy it.  🙂

In writing it, I started from thinking about how a starship would actually operate, if constrained by real physics (as we currently know it).  As an Engineer, I immediately started thinking about a workable design.

You couldn’t stay in zero-G for the years it would take to get to another star system, even if you travelled at close to the speed of light.  You’d lose all your muscle mass and develop wicked osteoporosis.  So that means you’d have to simulate gravity.  As far as we know, there’s no way to create an artificial gravity field, so the next best thing would be to use centripetal acceleration: spinning the ship.  Of course, you wouldn’t want the entire ship to spin, for a number of reasons.

1. You need gyroscopes to be able to tell where you’re going, and gyroscopes need a stable platform to operate correctly
2. Plotting your position for navigation purposes would require taking sitings off specific stars, and it’s really hard to do that if you’re constantly spinning.
3. Maneuvering the ship would be really difficult without a stable platform to mount the thrusters.
4. Communication antennae in the frequencies you’d need for the long distance communication required on interstellar journeys are highly directional.  You’d need to be able to point the antenna at the desired target.  Again, really hard to do if you’re spinning.
5. If you encountered any objects ahead, you’d want to be able to take a look at them, which means you’d need some cameras.  Really, you’d need telescopes.  You’re not going to be able to track a camera in well from a spinning platform.
6. Sometimes you really want a window view that isn’t constantly rotating.

All those reasons and more led me to decide the ship would need to have a central, stable, hub and spinning rings for the crew’s quarters.  Rings, not ring.  If you just tried to spin one ring, conservation of angular momentum dictates that you’d end up spinning the central hub the opposite direction, at the same speed.  That defeats the purpose.  So you’d need two rings, rotating in opposite directions.  They’d need to be large, because the larger they are, the slower they can turn while still getting the acceleration you want at the perimeter.  And because if you’re going to build a starship, it better be big enough to carry sufficient passengers and cargo to be economical.  So I made my rings a kilometer in diameter, fifty meters wide and three decks tall.  That’s a lot of cargo storage volume.

That’s great while the ship’s coasting between the stars.  But what about when the engines are actually firing?  In that case, the acceleration vector would run straight down the length of the ship.  If you were in a spinning ring at that point, you’d feel centipetal acceleration pushing you outwards and the acceleration from the engines pushing you backwards.  So you’d get stuck in a corner.  With that in mind, I determined you’d need to secure the ring rotation and have separate living quarters for the crew while the engines are firing.  Since at 1G it would take about a year to accelerate to 95% of the speed of light (without taking into account the time dilation caused by relativistic effects as you got faster), and another year to slow down again, they’d have to live in those quarters for a while.  The best place for the acceleration quarters, as I called them, would be within the central hub and arranged like the floors of a building, with the engines at the bottom.

Awesome.  But that means all the passengers would need to move around, too.  I got around that by just inventing cryo-suspension.  It’s a common ploy folks have used in science fiction: just put everyone to sleep, slow down their metabolism.  Works wonders.

Still, that leaves the crew with a long journey.  I chose to write about the journey from Gliese 581 back to Earth, since Gliese 581g is an (uncomfirmed) earth-like planet in the goldilocks zone around its star.  It’s 20.5 light years away.  Even with time dilation, if you count acceleration and deceleration time you’re looking at a 8 to 10 year trip for the crew.  That’s a lot of time to sit and monitor panels, to say nothing about the fact that it’s really asking a LOT of a guy or gal to devote ten years of his or her life to a single voyage, essentially out of contact with everyone, no matter how much he or she might get paid for it.  So knowing what I know about how to run a ship, watch rotations, and the like, it made sense to me that the crew wouldn’t stay up for the entire journey.  I decided to split the journey into one year shifts.  That increases the total crew compliment, but doesn’t really add to the amount of consumables they’d have to store onboard, since the off-shift crew would be in cryo-suspension.  So that worked nicely.

Now, food and air recycling.  Hydroponics.  Done.

Power.  Solar arrays could work well within a star system, but once you get into deep interstellar space, the light from the stars is going to be pretty dim (think of the night sky).  So you’d have to have a reactor onboard.  I chose fission, since we don’t know how to make fusion work well yet.  Again, this is nothing unusual in science fiction, or science fact, discussions.  But I’ve been puzzled when I read articles about NASA or the latest thoughts about how to build long range spacecraft.  They always talk about how a nuclear reactor would be awesome, but the shielding would screw you because it would have to be so massive.

To that, I say fooey!  Dude, it’s a spaceship.  It doesn’t have to be sleek looking.  It doesn’t have to be all in one piece.  There are three ways to lower radiation exposure: time, distance, and shielding.  Time is easy: don’t spend much time near the plant.  Shielding is the issue.  So use distance.  Radiation flux drops off at the square of the distance from the source.  So stick the reactor a couple kilometers aft of the crewed area, with structural members to transmit the thrust from the main engines to the rest of the ship and a small, shielded access tube so you can get back there for maintenance if necessary.  Problem solved.

At least from the reactor.  Background radiation exposure, particularly from cosmic rays, which are charged particles, is a big concern to long duration spaceflight also.  On earth we’re protected by our magnetic field and the earth’s atmosphere.  It’s not perfect, but it seems to me it wouldn’t be that hard to construct coils on the exterior of a starship to generate an artificial magnetic field around the ship.  That would repel charged particles, but wouldn’t do much for gamma and X-rays.  I gotta think that in deep interstellar space, away from stars, the overall gamma flux would be pretty low, though.  With the cosmic ray problem dealt with, maybe there wouldn’t need to be much done for gammas.  But for argument’s sake, I think it’s safe to say that on a multi-million kilogram ship, adding a few kilograms for lead shielding in he hull probably wouldn’t be that big a deal.

Finally, propulsion.  I just invented plasma engines.  I figure they work similarly to an ion drive.  An ion drive shoots charged particles out a nozzle on the back of the ship.  You get thrust from the reaction force of the particles leaving.  You can get a ship going pretty fast with an ion drive (we’ve done it already), but the acceleration is really really slow.  So I just called it plasma drive, and pretended the high energy of the plasma has the same effect, but larger.  It probably would, so that’s ok.  Plus it’s fiction.  That said, in my design the reactor doesn’t directly power the main engines.  All the reactor does is provide electricity to run the plasma generators, which convert engine fuel into the high energy plasma used to propel the ship.  That works out nicely for a couple reasons.  First, it means the reactor can be smaller, and its associated systems simpler.  Also, the engine fuel can act as additional shielding.

So you take all that, throw in a shuttle bay (because every starship worthy of the name HAS to have a shuttle bay), and voila!  You’ve got yourself a starship.

Pretty cool, huh?

Here’s hoping Writers of the Future thinks so.

🙂