1g Acceleration Spaceship Design

In my story, a ship is built in orbit around Earth, designed for a 20-person scientific expedition to a planet 11.4 ly away. It will accelerate at 1g for half the distance, then flip around and accelerate at 1g in the opposite direction until it comes to a stop. It's not designed to ever enter an atmosphere.

Technology in this world is arbitrarily powerful within known laws of physics, and they're able to produce large quantities of antimatter and perfectly convert that fuel's rest mass into kinetic energy via a gamma ray drive. In fact, they can even make solid antimatter, so if the fuel source was made of something like Bismuth and anti-Bismuth, it could take up very little space. They can also harvest matter for fuel at their destination.

I assumed that the habitat they'd need for the journey would weigh 0.5 million kg (this is comparable to the mass of the ISS, and while obviously this would need to be much larger and self-sustaining, it's also made with futuristic ultra-light materials) This handy calculator tells me that the total mass including fuel will come out to around 100 million kg.

This sounds like an absurd number until you realize that the Empire State Building weighs about 3 times that much. Piece of cake for an advanced civilization. (Did I mention they can get the materials to orbit with a space elevator?) More specifically, the mass is equivalent to 10,000 m^3 of Bismuth, or a 10x10x100 m building's worth, plus the habitat on top (some of the material can double as a radiation shield during the journey).

Given all of that, my question is simple: What would the ship look like?

My thoughts so far (feel free to contradict me if I made an incorrect assumption):

1. The ship looks more or less like a skyscraper. After all, it's roughly skyscraper-sized, and it needs to hold itself up under 1g of acceleration, just like skyscrapers on Earth do. But the lower 100 floors or whatever will be fuel.
2. The bottom of the ship is a lattice of parabolic dishes. The idea is that the gamma rays will be produced at the foci and reflected to generate thrust. However, I'm not convinced that a material capable of reflecting gamma rays is even physically possible. If there's an alternative, what is it and what would it look like?

posted about 5 years ago

Gilad M‭

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