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Orbital Insertion and Space Combat Tactics – Part 3

Published April 20, 2016 in Science , Science Fiction , Space - 0 Comments

One issue that is almost universally ignored in science fiction these days is the role of orbital mechanics in space combat tactics. Science fiction space combat tends to be written or visualized as if the spacecraft involved have nearly infinite energy and thrust available. Occasionally this is due to the writers or visual effects technicians consciously simplifying things for viewers. Unfortunately, however, most of the time it’s simply due to the writers being woefully ignorant of the subject.

In Part 1 we showed that any reasonable account of space combat in near-to-medium-future hard sci-fi must account for orbital mechanics. In Part 2 we discussed that pros and cons of higher orbits and lower orbits. However, we assumed that both spacecraft occupied the same orbital plane and that they were both orbiting in the same direction. What happens if we change these assumptions?

The first obvious choice is to consider two spacecraft orbiting in opposite directions but in the same plane (aka a retrograde orbit). Assuming that the two spacecraft are orbiting at the same altitude (and hence the same velocity), these spacecraft will only encounter each other twice on each orbit, and then only briefly.

Let’s consider for a moment two spacecraft occupying a Low Earth Orbit – say around 250 miles (such as the International Space Station). Such an orbit makes a full cycle every 92 minutes, which means that the two spacecraft would only be able to engage each other once every 46 minutes. The duration of the engagement would depend upon the range of each vessel’s weaponry. It should be readily apparent that long range weapons are of great advantage in almost all space encounters. They clearly show their advantage here.

In this particular scenario, weapons with a high burst rate but a long down time become tactically useful. For example, an energy weapon that requires a long time to charge but packs a major punch when fired might actually be practical in this case – provided it can be charged in less time than it takes to encounter the adversary again.

Likewise, shielding that holds up well to burst fire but doesn’t do well under sustained bombardment would be very useful here. The real world offers scant examples of this, but science fiction is littered with various energy shields that exhibit this exact characteristic. Just like our hypothetical energy weapon above, these shields could recharge in between engagements and provide protection.

A military ship equipped with these kinds of weaponry, then, might deliberately choose to enter a retrograde orbit relative to its opponent. On the other hand, a vessel with poor burst capability but built to take a beating might prefer to match orbits and slug it out.

Polar Orbit

Polar Orbit

Alternatively, our spacecraft might choose to enter an orbit with an entirely different angle of declination compared to our opponent. The extreme example would be to have one craft in a polar orbit while the other vessel occupies an equatorial orbit. In this case, the orbits would be angled at 90 degrees to one another.

It is critical to observe that even though the orbits intersect each other twice on every pass, due to orbital timing the spacecraft themselves might never actually encounter each other on these orbits. This is true whether the relative angle is 90 degrees or 1 degree.

This kind of configuration would favor a spacecraft that has both plenty of fuel for maneuvering and a very advanced navigational computer. Very careful maneuvering – consisting of burns to speed up and slow down ones orbit (and by consequence, raise and lower the orbit) could precisely control the timing of the orbital intersections. Depending upon the goals of the maneuvering craft, this could be used to either ensure that the two craft do meet or to ensure that they don’t. Of course, if the adversary also has high maneuvering capability and desires the opposite goal then the game is now on to see which captain can outsmart the other!

Equatorial Orbit

Equatorial Orbit

This kind of scenario absolutely requires a strong navigation computer. What you will not see here is the typical Hollywood scene of a captain standing on the bridge ordering a maneuvering burn “now!” Instead, humans would instruct the computer on the desired goals and the computer would control the timing of the burns. Human beings would not be able to manually control the burns so as to achieve such delicate timing.

This scenario would also favor two distinct kinds of vessels. Spacecraft with major weaponry designed to disable or destroy an opponent instantly or very quickly would find this kind of approach advantageous. Likewise, poorly armed but highly maneuverable spacecraft would find this configuration an ideal way to avoid encountering an enemy altogether. Although there are many others who might adopt this, one might find it useful to think of the first group as “pirates” and the second group as “smugglers.”

Finally, we must also consider highly elliptical orbits. Like angled orbits, elliptical orbits alter the timing and locations when two spacecraft would actually encounter one another. The timings and breakdowns become very complex. Are both orbits elliptical or is one circular? Are the two elliptical orbits aligned or are they angled with each other? Or are they in the same plane, but skewed? The possibilities quickly become very complex, but the considerations are essentially the same as discussed above with orbits of differing angles. Once more, an advanced navigation computer becomes essential to even have a prayer of tactically controlling the encounter.

In Part 1 we showed that we must account for orbital mechanics. In Part 2 we discussed orbits of differing altitude and velocity. Here in Part 3 we’ve discussed retrograde orbits and non-aligned orbits. In Part 4 we’ll discuss maneuvering itself in more detail.

Orbital Insertion and Space Combat Tactics

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