Distances in Aliens & Asteroids

Though we often talk about space travel in Aliens & Asteroids, we usually hand wave over some of the huge distances involved. So let’s take a look at how to rectify that problem.

Though we are dealing with space combat and space travel, I didn’t want to get completely bogged down in the distances we were covering in terms of story. Very few people really want to know how far it is from The Shire to Mount Doom when you come down to that level of detail at the game table, so I didn’t want that kind of detail getting in the way of exploring with the characters.

As a result, I came up with a very rough rule of thumb: it’s about 4 hours from Luna to the Field. Everything else should be able to be figured out from there. But how, exactly?

The solar system consists of the Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. Elements of this image furnished by NASA

Well, I started looking at everything in terms of Astronomical Units (AU). That’s the distance from Earth to the Sun. The Dominion started on Earth and we as a species tend to feel like we’re the center of the universe, so it only made sense that our self-aggrandizing would continue as we pushed beyond our solar system. 

One AU is 93,000,000 miles. That’s a lot of miles. We’re only about ½ AU from Mars and we’re even closer to Venus at a bit more than ¼ AU. They are in the neighborhood, but from there the distances get crazy.

The distance from Earth to the Field is roughly 1.75 AU. That’s more than 160,000,000 miles from home. And Earth to Neptune, where BANCE-3 happens to be sitting? 29 AUs! That’s more than 2.5 billion miles away. So how long is that going to take? 

Using my rough rule of thumb of four hours from Luna to the Field, the math didn’t actually work out. 40 million miles an hour? Seemed like a bit of a stretch. 

So I started doing some research into propulsion techniques that were in the realm of possibility. I found this great article at Universe Today from 2018 talking about using Catalyzed Fusion to go 2.1 million mph. That’s still crazy fast, but at least in the realm of the theoretically possible. 

If that’s possible, I figure we should be able to improve it by a few orders of magnitude in the next 200 years. And I decided that ¼ of an AU (roughly 23 million miles) was a reasonable number to travel in one hour in a scientifically-advanced future.

Abstract circular speed background. Centric motion of star trails. Starburst dynamic lines or rays. 3D rendering.

Yes, I know we’re not talking about accelerating and decelerating, or the forces of inertia that might make starting and stopping without destroying things a challenge. But this is a game and there is some “fiction” in our science fiction even if I want to ground it a little bit in what is realistically possible.

That bumped our 4 hour trip to the Field to about 7 hours, but it was still a reasonable number. And when I started combining it with some data on the distances between other planets [https://theplanets.org/distances-between-planets/], I came up with some reasonable times for travel in the Sol system.

Here’s what I ended up with:

  • Earth to Venus = 0.28 AU, or 1.12 hours 
  • Earth to Mars = 0.5 AU, or about 2 hours
  • Earth to the Field = 1.75 AU, or about 7 hours
  • Earth to Jupiter = 4.2 AU, or about 16.8 hours (less than a day)
  • Earth to Saturn = 8.52 AU, or about 34 hours (about a day and a half)
  • Earth to Uranus = 17.7 AU, or about 71 hours (nearly 3 days)
  • Earth to Neptune = 29 AU or about 116 hours (nearly 5 days)

It may not be perfect, but now at least I have a rational explanation for how long it takes to get around our solar system in 2229.

Let me know if you use these rough guidelines in your games and how they work out!

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