I've already considered that they may file their horns down, but keeping in mind that their horns gradually regrow, it is an inconvenient solution.
This is what their horns typically look like:
They do have very strong neck muscles, but I don't want the helmet to be overly cumbersome.
I'm open to other solutions that circumvent a helmet, too, but still fill the required needs, which are:
- Allows the alien to breathe in space or on inhospitable planets
- Keeps their head at the correct pressure in low and high pressure environments
- Protects the head from radiation, heat and cold
- Protects the eyes from intense light
Details about the horns:
- Their horns have no blood supply or nerves except at the base; the base of the horn is responsible for regrowing, repairing, and shedding the horn.
- They can withstand large temperature ranges (albiet less so in the cold margins) provided that the transition is slow, otherwise the horns will fracture.
- If exposed to sand storms or very acidic environments, the horns will wear down rapidly or in the latter case, decompose.
- When the horn is regrowing, a velvet like sheath with a blood supply conceales it. If this blood supply is completely constricted, the growing horn will die and fall off. If not enough blood is allowed, the horn will be bendy, like cartilage, and grow at a reduced rate.
- The horns regrow from the base, not the tip. They are triggered to fall off entirely when a high margin of damage has been accumulated. (Assume they have an innate way of detecting this without pain-triggering nerves, like how a tree can regrow from being cut down, or how plants have measures of repairing themselves when injured without feeling pain)
The technology that they have available to them is equal to what you can expect from space-fairing human technology, as they were uplifted by humans at their equivalent of the Bronze Age. Assume this technology is advanced enough to make self sustaining migrant ships to traverse the Milky Way, but not advanced enough to travel near lightspeed, nor resourceful enough to entirely colonize barren, unsustaining planets.