Modern SFB and FC have specialized SSDs for ground bases, installations on the surface of a planet or moon that can engage in combat with ships in space. This was not always the case. In early editions of SFB, ground bases used the same SSDs as base stations and battle stations. A few simple rules allowed these to assume the role of planet-based facilities quite nicely, and the same can easily be done in Starmada.
First, there is the issue of shields. Base and battle stations both have strength 9 shields all around. I recommend considering the ground base to have a single double-strength shield. Simply cross out two of the shield tracks and consider the remaining pair to be one continuous 18-point shield that covers the base like a dome, but otherwise behaves in all ways the same as other SFU shields.
Next is the issue of firing arcs. If the planetary body is a single hex in size, designate a hex side as the location of the base. The base's weapons will all be able to fire into a single 180-degree arc made up of the hex side it occupies and the two directly adjacent to it (one on each side). Weapons fired at the base must have line of sight to the hex side where the base is located.
In the case of a multi-hex planet, choose one of the planet's edge hexes as the base's location. Depending on the planet's diameter and the hex you choose, the base might have two or three outward-facing hex-sides to fire its weapons through (and to be fired upon by enemies).
Planetary rotation can be safely ignored, as it is not rapid enough to alter the firing and defensive arcs involved within the length of the average scenario.
Those who have played SFB might remember that planetary atmospheres had deleterious effects on phaser fire in that game, but since Starmada is based on FC, where such is not the case, we need not concern ourselves with this.
Note that ground bases are even more unassailable than their space-based counterparts, given the fact that they can simultaneously fire all of their weapons at a single target due to their unified firing arc.
Consider utilizing base stations as colony defense facilities and battle stations as military installations. Grounded defense satellites can also be used as automated defenses for civilian and scientific outposts.