# Space Cold/hot War with periodical cycles

It's the far away year 2000 and the Soviets and the Allies are locked in war, while on Earth side things are your constant bloodbath their assets in space are stationed in orbits that keep them far away for most of the time, but at certain periods they are brought close enough to start shooting at each other! So, my question is:

How to have two opposing forces in different orbits that will periodically intersect, but are kept away from each other for most of the time?

• Could you clarify as to what sort of "periodically" you're after, here? Monthly? annually? decadal? Additionally, what sort of "close enough" is needed? kilometers? thousands of kilometers? Cold-war-alt-future tech is a little ill-defined. How long do you need the space stations to be within zapping-range of each other? Just a few minutes? Or are days/weeks/months OK? The variables here mean there are a wide range of options, and they'll have very different effects on your setting. Commented Jun 5 at 15:26
• There are three main things that need to be clarified: How often do they meet, how close do they need to come, and how long are they within range? Commented Jun 5 at 15:41
• Something like three months were the two stations are in range of each other and 9 months where they are too far apart for any meaningful attack. Their tech is on the lower tiers of scifi, so no artificial gravity or the likes, more like an 80's The Expanse. They should come close enough that it becomes basically a broadside battle between the stations Commented Jun 8 at 12:45

Elliptical Orbits

Image courtesy Terraforming Wiki.

This is easily solved using elliptical orbits. If a circular orbit is defined as axis A = axis B, then an elliptical orbit is defined as axis A > axis B. Whether you ignore the mathematics of orbits or not, you can make the axis lengths and orbital speed of any number of orbits different enough to rationalize any combination of close-enough-to-shoot-at opportunities you wish.

And if you really want to narrow the shoot-at-one-another window, rather than making all the orbits on the same plane (e.g., the plane of the ecliptic), angle the orbits all over the place. Now they have two chances to shoot at each other and each opportunity lasts only 45 minutes (or some such). The third dimension is your friend!

I leave it as an exercise for the reader to work out the math. Or, like in most stories, you can ignore the details and simply state that due to their elliptical orbits, "the opposing forces only have three days to shoot at one another every 2.2 years" (or whatever you want).

Objects orbiting the sun at different speeds but with similar orbits will spend most of their time at a considerable distance from each other, but for a short period of time they will pass very close. Astronomers call this the transfer window, where it is possible to travel from one object to another.

For example. Two space stations orbiting the sun at different speeds with orbits that have a perihelion and aphelion of approximately 3 astronomical units will spend some Earth years very far from each other, reaching a distance of 6 AU between them at the furthest point, but for a short window of time they will pass dangerously close.

So... Make the bases of the opposing forces orbit the Sun at different speeds, or orbit different celestial bodies in the solar system.

There's really only three ways to not get what you want - 1) the two ships are in the exact same orbit and are constantly near each other; 2) the ships' orbits don't intersect and they are never near each other; or 3) the ships' orbits intersect but have periods which are integer multiples, resulting in the possibility of never being near.

Any other configuration that has intersecting orbits with periods that aren't integer multiples will have the two objects infrequently passing near to one another over, with at least one of the objects going through multiple orbits before a near-pass.